UFC 3-250-04 16 January 2004 including Change 2 - 29 July 2009

UNIFIED FACILITIES CRITERIA (UFC)

STANDARD PRACTICE FOR

CONCRETE PAVEMENTS

APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED

UFC 3-250-04 16 January 2004 including Change 2 - 29 July 2009

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UNIFIED FACILITIES CRITERIA (UFC)

DESIGN: STANDARD PRACTICE FOR CONCRETE PAVEMENTS

Any copyrighted material included in this UFC is identified at its point of use. Use of the copyrighted material apart from this UFC must have the permission of the copyright holder. U.S. ARMY CORPS OF ENGINEERS (Preparing Activity) AIR FORCE CIVIL ENGINEER SUPPORT AGENCY Record of Changes (changes are indicated by \1\ ... /1/) Change No. Date Location 2 29 July 2009 Removed FA designation to indicate unification This UFC supersedes TM 5-822-7, dated 16 August 1987 \2\and UFC 3-250-12N dated 8 June 2005/2/. The format of this UFC does not conform to UFC 1-300-01; however, the format will be adjusted to conform at the next revision. The body of this UFC is the previous TM 5-822-7, dated 16 August 1987.

UFC 3-250-04 16 January 2004

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FOREWORD including Change 2 - 29 July 2009\1\ The Unified Facilities Criteria (UFC) system is prescribed by MIL-STD 3007 and provides planning, design, construction, sustainment, restoration, and modernization criteria, and applies to the Military Departments, the Defense Agencies, and the DoD Field Activities in accordance with USD(AT&L) Memorandum dated 29 May 2002. UFC will be used for all DoD projects and work for other customers where appropriate. All construction outside of the United States is also governed by Status of forces Agreements (SOFA), Host Nation Funded Construction Agreements (HNFA), and in some instances, Bilateral Infrastructure Agreements (BIA.) Therefore, the acquisition team must ensure compliance with the more stringent of the UFC, the SOFA, the HNFA, and the BIA, as applicable. UFC are living documents and will be periodically reviewed, updated, and made available to users as part of the Services’ responsibility for providing technical criteria for military construction. Headquarters, U.S. Army Corps of Engineers (HQUSACE), Naval Facilities Engineering Command (NAVFAC), and Air Force Civil Engineer Support Agency (AFCESA) are responsible for administration of the UFC system. Defense agencies should contact the preparing service for document interpretation and improvements. Technical content of UFC is the responsibility of the cognizant DoD working group. Recommended changes with supporting rationale should be sent to the respective service proponent office by the following electronic form: Criteria Change Request (CCR). The form is also accessible from the Internet sites listed below. UFC are effective upon issuance and are distributed only in electronic media from the following source: • Whole Building Design Guide web site http://dod.wbdg.org/. Hard copies of UFC p rinted from electronic media should be checked against the current electronic version prior to use to ensure that they are current. AUTHORIZED BY: ______________________________________ DONALD L. BASHAM, P.E. Chief, Engineering and Construction U.S. Army Corps of Engineers

______________________________________DR. JAMES W WRIGHT, P.E. Chief Engineer Naval Facilities Engineering Command

______________________________________ KATHLEEN I. FERGUSON, P.E. The Deputy Civil Engineer DCS/Installations & Logistics Department of the Air Force

______________________________________Dr. GET W. MOY, P.E. Director, Installations Requirements and Management Office of the Deputy Under Secretary of Defense (Installations and Environment)

ARMY TM 5-822-7AIR FORCE AFM 88-6, Chap. 8

DEPARTMENTS OF THE ARMY AND THEAIR FORCE TECHNICAL MANUAL

STANDARD PRACTICE FOR CONCRETE PAVEMENTS

DEPARTMENTS OF THE ARMY AND THE AIR FORCEAUGUST 1987

REPRODUCTION AUTHORIZATION/RESTRICTIONS

TECHNICAL MANUALNo. 5-822-7AIR FORCE MANUALNo. 88-6, Chapter 8

HEADQUARTERSDEPARTMENTS OF THE ARMY

AND THE AIR FORCEWashington, DC 16 August 1987

STANDARD PRACTICE FOR CONCRETE PAVEMENTS

Paragraph Page

PURPOSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SCOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RESPONSIBILITIES, STRENGTH, AND AIR CONTENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .CEMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ����AGGREGATES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ADMIXTURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . POZZOLANS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MISCELLANEOUS MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .WATER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . SAMPLING AND TESTING OF MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DELIVERY AND STORAGE OF MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GRADE CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PROPORTIONING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SUBGRADE, BASE, FORMS, AND STRING LINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .BATCHING AND MIXING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PLACING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .FIELD TEST SPECIMENS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FINISHING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CURING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GRADE AND SURFACE -SMOOTHNESS REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .TOLERANCES IN PAVEMENT THICKNESS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .REPAIRS OF DEFECTIVE PAVEMENT SLABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .JOINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PAVEMENT PROTECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MEASUREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX A: REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .APPENDIX B: THIN BONDED RIGID OVERLAYS FOR RIGID PAVEMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APPENDIX C: STEEL-FIBER- REINFORCED CONCRETE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .APPENDIX D: ROLLER-COMPACTED CONCRETE PAVEMENTS; DESIGN AND CONSTRUCTION............

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A-1B-1C-1D-1

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Figure 1.2.3.

D-1.D-2.D-3.D-4.D-5.

Table 1.2.3.4.5.6.7.8.

C-1.C-2.D-1.

LIST OF FIGURES

Prediction of concrete rate of evaporation.Air Force runway grooving requirements.Special joint between new and existing pavement.Typical layout for RCCP test section.Compaction of first paving lane.Compaction of interior paving lanes.Construction of a cold joint.Two-lift cold joint preparation.

LIST OF TABLES

Approximate relation between water-cement ratio and strengths of concreteCoarse aggregate size groupsGrading of coarse aggregateDeleterious materials in coarse aggregates for airfield and heliport pavementsDeleterious materials in coarse aggregates for other pavementsGrading of fine aggregateDeleterious substances in fine aggregateSurface smoothness - airfield and heliport pavementsSelected characteristics of fiber-reinforced airfield pavementsInterim suggested maximum joint spacing for steel-fiber-reinforced concreteVibratory rollers used in RCCP construction

STANDARD PRACTICE FOR CONCRETE PAVEMENTS

1. Purpose. This manual provides information on thematerials and construction procedures for concretepavements.

2. Scope. This manual describes the constituents tobe used in concrete, the procedures to be used inmanufacturing concrete, and the equipment andprocedures to place, texture, and cure concrete forpavements.

3. Responsibilities, strength, and air content.

a. Responsibility for mixture proportioning. Theresponsibility for mixture proportioning must beclearly assigned to either the contractor or thecontracting officer in the project specifications.When the contracting officer is responsible formixture proportioning, he will approve all concretematerials as well as determine and adjust propor-tions of all concrete mixtures as necessary to obtainthe strength and quality of concrete required for thepavements. Cement will be a separate pay item inthe contract. When the contractor is responsible formixture proportioning, he will control all proportionsof the concrete mixture necessary to obtain thestrength and quality of the concrete required for thepavements, and cement will not be a separate payitem in the contract. However, the contracting officeris responsible for approving the quality of allmaterials the contractor uses in the concrete.

b. Approval responsibility. The contracting officeris responsible for approval of all materials, mixtureproportions, plants, construction equipment, andconstruction procedures proposed for use by thecontractor. The contractor must submit proposedmixtures if he is responsible for mixture propor-tioning; samples of all materials; and detaileddescriptions of all plants, construction equipment,and proposed construction procedures prior to thestart of construction.

c. Flexural strength. Structural designs are basedon flexural strengths that the concrete is expectedto obtain at 28 days for road pavements and 90 days

for airfield pavements. These ages are not adequatefor quality control in the field since a large amountof low-strength concrete could be placed beforestrength tests on samples revealed the problem.Correlations can be established between a 14-daystrength and the 28- or 90–day strength used indesign, and this correlated 14-day strength can beused as a strength check for a more timely concretemixture control in the field.

(l.) Materials and flexural strength. To selectsuitable flexural strengths for the design ofpavements and for inclusion in contract specifica-tions, the contracting officer should have reliableinformation regarding flexural strengths obtainablewith acceptable concrete materials which are availablein the vicinity of the project. Typical design valuesfor flexural strength of paving-quality concretevary from 500 to 750 pounds per square inch (psi).Numerous tests indicate considerable variation inthe flexural strength of concrete when differentaggregates or different cements are used. There aresome indications that aggregate shape and modulusof elasticity are relatively more important inconcrete flexural strength than in compressivestrength. Also, after optimum flexural strength isreached, there usually is little increase in strength,even with a large increase in cement content. Mixtureproportioning studies will be made in accordancewith ACI 211.1 (see app A for referenced publications)to determine the flexural strengths to be used forthe design of the project. The water-cement ratio-strength relations for mixture proportioning in ACI211.1 are given in terms of compressive strength.Table 1 gives some approximate guidance forrelating the concrete modulus of rupture to thecompressive strength-water cement ratio relation-ships given in ACI 211.1. All aggregates, cementitiousmaterials, and admixtures used in the mixtureproportioning studies will be representative ofmaterials available for use in pavement construction.In selecting a flexural strength for pavement design,suitable allowance will be made for variations instrength indicated by tests of different combina-tions of aggregate and cement. Pavement designwill be based on a realistic and economical strengthobtainable with available materials.

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Table 1. Approximate relation between water-cement ratio and strengths of concrete (modified from ACI 211.1)

(eq 1)

TM 5-822-7/AFM 88-6, Chap. 8

characteristics of freshly mixed concrete and isrequired for the freezing and thawing resistance ofhardened concrete. The use of entrained air inconcrete will reduce strength, but because of theimproved workability in the freshly mixed concrete,adjustments in aggregate proportions and reductionof water are normally possible that will negate or atleast minimize the loss of strength. Proper propor-tioning and control of the air-entrained concretemixture are essential in order to derive maximumbenefits from improvement in the placability anddurability of concrete with a minimum effect onflexural strength.

(2.) Percentage of air content. The specified aircontent will be 6 ± 1½ percent for concretepavements located in regions where resistance tofreezing and thawing is a prime consideration, andwill be 5 ± 1½ percent for concrete pavementslocated in regions where frost action is not a factorand air entrainment is used primarily to improve theworkability and placability of freshly mixed concrete.Air content will be controlled in the field at the pointwithin the specified range most appropriate for localconditions depending upon the severity of exposureand the quality and maximum size of aggregate. Ifslag aggregate is used, the air content will be deter-mined by the volumetric method as described inASTM C 173. Where the aggregate is of compara-tively poor quality or when the maximum size is 1%inches or less, the air content will be controlled at 6± 1 percent. In such instances, where resistance tofreezing and thawing is not a prime consideration,the air content will be 5 ± 1 percent. If furtherreduction in the air content or the use of non-air-entrained concrete is necessary, prior approval willbe obtained from HQDA (DAEN-ECE-G), Wash-ington, DC 20314-1000 or the appropriate Air Forcemajor command.

e. Cement content. Either the contractor or thecontracting officer may be responsible for mixtureproportioning. When the contractor is responsiblefor mixture proportioning, no separate payment willbe made for cement. When the contracting officer isresponsible for mixture proportioning, no limits forthe quantity of cement content will be included inthe contract specifications; the quantity of cementused per cubic yard of concrete will be determinedby the contracting officer, and cement will be paidfor under a separate bid item. When the concreteproposed for use on a paving project has a cementcontent of less than 470 pounds per cubic yard, priorapproval will be obtained from HQDA (DAEN-

ECE-G) or the appropriate Air Force major command.When concrete proportioning is the responsibility ofthe contractor and the cement content is less than470 pounds per cubic yard, the results should beverified by two Corps of Engineers Divisionlaboratories or commercial laboratories prior tosubmittal. The results of mixture proportioningstudies for proposed aggregates and cements andthe results of qualitative tests on aggregates and onresulting concretes will be submitted with requestsfor approval.

4. Cement.a. Five portland cements designated as Types I

through V are marketed today. ASTM C 150 providesa detailed specification for these cements. Type Iportland cement is common or ordinary cement thatis supplied unless another type is specified. Type IIis modified portland cement that provides moderateresistance against sulfate attack and a lower heat ofhydration than Type I cement. It is common forcement to be manufactured to meet the physical andchemical requirements of both Type I and II cements.

b. Type III cement is high early-strength cement.Ultimate strength is about the same as Type Icement, but Type III cement has a 3-day compressivestrength approximately equal to the Type Icement’s 7-day strength. The cost of Type IIIcement in lieu of Types I or II cement can only bejustified when early strength gain is needed to openpavements to traffic or the high heat of hydration isneeded for cool construction periods. Type IVcement has a low heat of hydration that may beuseful in mass concrete but is not likely to beencountered in pavement construction. Type Vsulfate-resistant cement should be used when theconcrete will be exposed to severe sulfate attack.The potential for severe sulfate attack exists whenthe concrete is exposed to water-soluble sulfate insoil or water in excess of 0.20 percent or 1,500 partsper million. The potential for moderate sulfateattack exists for sulfate contents in excess of 0.10,or 150 parts per million.

c. High alumina cement, also known as aluminousor calcium aluminate cement, gains most of itsstrength in one day, has a high exotherm, is resistantto chemical attack, and is a refractory material.When exposed to warm, moist conditions, it willundergo a long-term strength loss. High aluminacement may find some specialized applications inpavement construction where its rapid strengthgain, high exotherm, or refractory properties

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TM 5-822-7/AFM 88-6, Chap. 8

outweigh its cost and long-term strength loss.d. There are also some expansive cements,

designated as Types K, M, and S in ASTM C 845,that may find some application where concreteshrinkage needs to be minimized or avoided.However, there is little experience with thesecements, and they will require careful investigationbefore use in pavement construction.

e. At least one United States manufacturer isactively promoting a slag cement made by grindingiron blast furnace slag. This may be substituted forup to 50 percent of the portland cement in a pavementmixture if tests show the required final propertiesare achieved in the hardened concrete. Preblendedmixes of portland-pozzolan (Type IP), and portland-slag cements (Type IS) are described in ASTM C 595and are acceptable for use in pavements.

5. Aggregates.a. Approval of aggregates. The contractor will use

aggregates from approved sources. If the contractorproposes to use aggregates from an unapprovedsource, the Government will be responsible forconducting tests to determine whether the proposedaggregates will meet the requirements of the project.Sampling and aggregate delivery costs will be borneby the contractor. The contract specifications willstate aggregate sample size, delivery location, andrequired evaluation time for the proposed aggre-gates. For small jobs requiring 1,600 cubic yards orless of concrete, all tests for aggregates from anunapproved source will be done by the contractor.

b. Quality. Aggregates must generally meet therequirements of ASTM C 33, as modified in thefollowing paragraphs. These requirements can beadjusted as necessary to reflect local experiencewith specific aggregates to insure economical use ofaggregates to meet project requirements. Themagnesium or sulfate soundness test (ASTM C 88)required in ASTM C 33 has not been consistentlysuccessful in identifying frost-resistant aggregate.Consequently, if an otherwise suitable aggregatefails this test, it should be further investigatedusing freezing and thawing tests as described inASTM C 666 or ASTM C 682 before it is finallyrejected. Similarly, if an otherwise suitable aggre-gate fails the Los Angeles (LA) abrasion test(ASTM C 131 or C 535), it can be accepted if it has ahistory of local use showing that it can be processedwithout unacceptable degradation and that it isdurable under weathering and traffic conditions

comparable to the project under investigation.c. Recycled concrete as aggregate. Existing

concrete may be taken up, crushed to suitablegradation, and re-used as concrete aggregate. Itmust meet all the requirements for gradation andquality that conventional aggregates must meet.All reinforcing steel should be removed. Duringcrushing, hammermill secondary crushers tend toproduce excess fines and should not be used. Therecycled concrete aggregates will not normallyrequire washing unless they have been contaminatedwith base or subgrade material. If the original pave-ment that is being recycled is D-cracked, then theconcrete should be crushed to a maximum size of ¾inch. When crushed concrete is being used as fineaggregate, the inclusion of some natural sand maybe required to improve the new concrete mixture’sworkability.

d. Alkali-aggregate reactions. Minerals in someaggregates can chemically react with the cementalkalis, resulting in an increase in volume thatplaces the concrete under expansive stresses whichmay result in map cracking, popouts, strength loss,and concrete expansion. Once started, the reactionand the resulting progressive deterioration of theconcrete cannot be stopped. These reactions aregenerally associated with aggregates containingpoorly ordered forms of silica, such as opal,chalcedony, chert, or flint (alkali-silica reaction),complex layer-lattice, and silicate minerals such asgraywackes, phyllites, siltstones, or argillites (some-times differentiated as alkali-silicate reaction), orargillaceous, dolomitic limestone (alakali-carbonatereaction). A petrographic investigation in conjunctionwith results of tests in accordance with ASTM C 227for alkali-silica expansion and ASTM C 586 foralkali-carbonate expansion is the most promisingapproach for identifying these problems. If possible,reactive aggregates should be avoided. If they cannotbe avoided, low-alkali cement should be specified. Iflow-alkali cement is not available or is overly expen-sive, some pozzolans and slag cements have beensuccessful in countering alkali-silica reactions, orreactive aggregate may be blended with non-reactiveaggregate to lessen the effect of the reactions.

e. Coarse aggregate.(l.) Composition. Coarse aggregate may be

natural gravel, crushed gravel, crushed stone, crushedrecycled concrete, or iron blast furnace slag. Thecrushing of gravel tends to improve the quality andthe bond characteristics and generally results in ahigher flexural strength of concrete than if uncrushed

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TM 5-822-7/AFM 88-6, Chap. 8

gravel is used. When mixture proportioning studiesor local experience indicates that a low flexuralstrength will be obtained with uncrushed gravel, thepossibility of obtaining higher strength by crushingthe gravel will be investigated. Elongated particleswith a width–to-thickness ratio in excess of 3 maynot exceed 20 percent by weight as determined byCRD-C 119. This requirement attempts to avoidintroducing structural planes of weakness in thefinished concrete, workability problems associatedwith an excess of particles of these shapes, anddurability problems that may develop if air andwater are trapped under flat and elongated particles.

(2.) Size and grading. The maximum size of thecoarse aggregate used in pavement concrete shouldnot exceed one-fourth of the pavement thickness. Inno case will the coarse aggregate exceed a 2-inchmaximum size. However, for pavement constructionin areas where aggregate popouts have been a problemor may occur, the coarse aggregate will not exceed1½-inch nominal maximum size. In areas where

“D” line cracking in pavements has been a problem,limestone aggregates should not exceed ½-inchnominal maximum size and should be of low absorp-tion. When the nominal maximum size of coarseaggregate is greater than 1 inch, the aggregatesshall be furnished in two size groups as shown intable 2, with gradings within the separated sizegroups conforming to the requirements of table 3.Where local practice provides size-group separationsother than as shown in table 2, local size gradingsmay be specified if approximately the same sizeranges are obtained and the grading of coarse aggre-gate when combined and batched for concrete is asrequired by mixture proportioning. For projectsrequiring 1,600 cubic yards or less of concrete,special grading requirements for coarse aggregateaccording to local practice may be substituted forthe gradings shown. Local State Department ofTransportation specifications for gradings may beused for those jobs requiring 1,600 cubic yards orless of concrete.

Table 2. Coarse aggregate size groupsL

Nominal Maximum Size Size Groups

1½ in. No. 4 to ¾ in.¾ in. to 1½ in.

2 in. No. 4 to 1 in.1 in. to 2 in.

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TM 5-822-7/AFM 88-6, Chap. 8

Table 3. Grading of coarse aggregate

S i e v e S i z eU . S . S t a n d a r d

Square Mesh

P e r c e n t a g e b y W e i g h t P a s s i n g I n d i v i d u a l S i e v e sNo. 4 to3 / 4 i n .

No. 4 to1 in .

3 / 4 i n . t o 1 in. to2 in .1 - 1 / 2 i n .

2 - 1 / 2 i n .

2 in .

1 - 1 / 2 i n .

1 in .

3 / 4 i n .

1 / 2 i n .

3 / 8 i n .

No. 4

No . 8

100

9 7 ± 3

50 ± ’20

7 ± 7

- - - - - -

100- - - -

100

9 7 ± 3100

9 5 ± 5 - -

- - - -

3 ± 3- - - -

- - - -

- - - -

(3.) Deleterious substances.(a) Pavements used by aircraft. Table 4 lists

the common deleterious substances and specifieslimits for these materials. The performance history

waive table 4 requirements for Air Force pavements.Upon request, the AFRCE and the using commandwill be furnished available engineering informationon local aggregates and behavior records on pave-ments made from them. A copy of the instructionsand the revised requirements will be furnished forinformation to the HQDA (DAEN-ECE-G) orAFESC as applicable. In the case of Air NationalGuard and Army pavements, the using commandwill be furnished information on the costs of aggre-gates complying with specification requirementsand on less costly local aggregates along withbehavior records on pavements made with localaggregates. However, requirements will be waivedonly if requested by the Air National Guard BaseDetachment Commander or the Army InstallationCommander with his assurance that operationalrequirements will be satisfied by a performance thatis equal to that of existing pavements constructedwith these less costly aggregates. Requests will besubmitted for approval to HQDA (DAEN-ECE -G)with proposed specification requirements, compara-tive cost estimates, and evidence that operationalrequirements will be satisfied.

of local aggregates contributing to pavementdefects will be the determining factor in setting thelimits for deleterious substances. The limits areintended to eliminate popouts and weatherouts inairfield pavements. Other deleterious substancesknown to contribute to popouts will be identified bythe contracting officer, and suitable limits will bespecified. Calcium oxide (CaO) and magnesium oxide(MgO) or a mixture thereof, in lumps, representingthe hard burned oxides from fluxing stone or refrac-tory brick should be added to the list of deleterioussubstances if air-cooled blast furnace slag is used asthe aggregate. Since the types of materials producingpopouts will vary for different areas, some adjust-ments of the limits may be desirable for individualprojects. Reductions in specified limits may bemade as necessary, but increases to permit the useof local aggregates that have an acceptable experiencerecord will be governed by the following procedures.Air Force Regional Civil Engineers (AFRCE) havebeen authorized to instruct division engineers to

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TM 5-822-7/AFM 88-6, Chap. 8

Table 4. Deleterious materials in coarse aggregates for airfield and heliport pavements.

Areas with Areas withMajor Popouts Minor Popouts

Severe a Moderate a Severe a Moderate a

Materials Weather Weather Weather Weather

Clay lumps 0.2 0.2 2.0 2.0

Shaleb 0.1 0.2 1.0 1.0

Material finer 0.5 0.5 1.0 1.0than No. 200 sievec

Lightweight particles 0.2 0.2 0.5 0.5

Clay ironstone 0.1 0.5 1.0 1.0

(Continued)

aSevere, moderate, and mild weather are defined as follows:

Air Freez- Average Precipitation for a Singleing Index Month During Period--1 Month Before

Weather for Coldest Average Date of First Killing FrostSeverity Year in 30* to Average Date of Last Killing Frost

Moderate 500 or less Any amount

Moderate** 501 or more Less than 1 inch

Severe 501 or more 1 inch or more

* Calculated as described in TM 5-818-2/AFM 88-6, Chapter 4.** In poorly drained areas, the weather should be considered severe

even though the other criteria indicate a rating of moderate.

b Shale is defined as a fine-grained thinly laminated or fissile sedimentary rock.It is commonly composed of clay or silt or both. It has been indurated by compac-tion or by cementation, but not so much as to have become slate.

cLimit for material finer than No. 200 sieve will be increased to 1.5 percent forcrushed aggregates if the fine material consists of crusher dust that is essen-tially free from clay or shale.

d The separation medium shall have a specific gravity of 2.0. This limit does notapply to coarse aggregate manufactured from blast-furnace slag unless contaminationis evident.

e Clay ironstone is defined as an impure variety of iron carbonate, iron oxide,hydrous iron oxide, or combinations thereof, commonly mixed with clay, silt, orsand. It commonly occurs as dull, earthy particles, homogeneous concretionarymasses, or hard shell particles with soft interiors. Other names commonly used forclay ironstone are “chocolate bars” and limonite concretions.

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TM 5-822-7/AFM 88-6, Chap. 8

Areas with Areas with

Materials

Chert and/or chertystone (less than

2.50 sp. gr. SSD) f

Claystone, mudstone,

and/or si ltstone g

Shaly and/or argilla-h

ceous limestone

Other soft particles

Total of al l deleteri -ous substancesexclusive of mate-rial finer thanNo. 200 sieve

Major Popouts Minor Popouts

Severe a Moderate a Severe a Moderate a

Weather Weather Weather Weather

0.1 0.5 1.0 5.0

0.1 0.1 1.0 1.0

0.2 0.2 1.0 2.0

1.0

1.0

l .0

2.0

1.0

3.0

2.0

5.0

f Chert is defined as rock composed of quartz, chalcedony, or opal, or any mixtureof these forms of silica. It is variable in color . The texture is so fine thatthe individual mineral grains are too small to be distinguished by the unaided eye.Its hardness is such that it scratches glass but is not scratched by a knife blade.It may contain impurities such as clay, carbonates, iron oxides, and other min-erals. Other names commonly applied to varieties of chert are flint, jasper,agate, onyx, hornstone, porcellanite, novaculite, sard, carnelian, plasma, blood-stone, touchstone, chrysoprase, heliotrope, and petrified wood. Cherty stone isdefined as any type of rock (generally limestone) which contains chert as lensesand/or nodules or irregular masses partially or completely replacing the originalstone. SSD = saturated surface dry.

gClaystone, mudstone, or siltstone is defined as a massive fine-grained sedimentaryrock which consists predominately of clay or silt without lamination or fissility.It may be indurated either by compaction or by cementation.

h Shaly limestone is defined as a limestone in which shale occurs as one or morethin beds of laminae. These laminae may be regular or very irregular and may bespaced from a few inches down to minute fractions of an inch. Argillaceous lime-stone is defined as a limestone in which clay minerals occur disseminated in thestone in the amount of 10 to 50 percent by weight of the rock; when these make upfrom 50 to 90 percent, the rock is known as calcareous (or dolomitic) shale (orclaystone, mudstone, or siltstone).

TM 5-822-7/AFM 88-6, Chap. 8

(b) Other pavements. For other pavements, be identified by the contracting officer, and suitablethe limiting amounts of deleterious substances in limits will be specified and materials defined wheneach size of coarse aggregate will be specified as necessary.shown in table 5. Other deleterious substances will

Table 5. Deleterious materials in coarse aggregates for other pavements

Material Percentage by Weight

Clay lumps and friable particles 2.0

Material finer than No. 200 sieve a 1.0

L i g h t w e i g h t p a r t i c l e s 1.0

Other soft particles 2.0

Note:

aLimit

The total of all deleterious substances shall not exceed5.0 percent of the weight of the aggregate. The percentageof material finer than No. 200 sieve shall not be includedin th i s t o ta l .

for material finer than No. 200 sieve will be increased to1.5 percent for crushed aggregates consisting of crusher dust thatis essentially free from clay or shale.

bThe separation medium shall have a specific gravity of 2.0. This

limit does not apply to coarse aggregate manufactured from blast-furnace slag unless contamination is evident.

(4.) Slag aggregate. Iron ore blast-furnace slagaggregates vary widely in properties depending onthe manufacturing and cooling processes used. Un-aged blast-furnace slag may contain free lime, butaging reduces this to acceptable levels. Properly agediron ore blast- furnace aggregate has a good historyof performance. Slag from steel mills, however, isnot acceptable as concrete aggregate because of thevarious oxides it contains.

f. Fine Aggregate.

(l.) Composition and shape. Requirements forcomposition and particle shape of fine aggregate arepurely descriptive, for example, natural and/ormanufactured sand, spherical or cubical, and nolimits are shown. A limit will be included for flat andelongated particles in fine aggregate, comparablewith the limit specified for coarse aggregate, whentests indicate that poor particle shape will affect the

workability and quality of the concrete. Shape willbe determined in accordance with CRD-C 120.

(2.) Grading, uniformity of grading, anddeleterious substances. The grading and uniformityof grading specified in table 6 for fine aggregate aredesirable for pavement concrete and can generallybe met at a reasonable cost within the continentalUnited States. However, if conformance with theserequirements will result in undue construction costsand if investigation of the available sources of fineaggregate in the locality indicates that limits otherthan specified are desirable, a request will be sub-mitted to HQDA (DAEN-ECE-G) giving completeresults of all tests conducted to substantiate thatconcrete of comparable workability, durability, andstrength can be produced without an increase incement content. The amount of deleterioussubstances in the fine aggregate shall not exceed thelimits shown in table 7.

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TM 5-822-7/AFM 88-6, Chap. 8

Tabk 6. Gnading of fine aggregate

Sieve Size, Cumulative Percentage by WeightU. S. Standard Square Mesh Passing Individual Sieves

3 /8 in . 100

No. 4 9 7 2 3

No. 8 8 5 2 5

No. 50 20 ± 10

No. 100 6 ± 4

Note: In addition, the fine aggregate, as delivered to the mixer,shall have a fineness modulus of not less than 2.40 normore than 2.90. The grading of the fine aggregate alsoshall be controlled so that the fineness moduli of at leastnine of ten samples of the fine aggregate as delivered tothe mixer will not vary more than 0.15 from the averagefineness moduli of all samples previously taken. Thefineness modulus shall be determined by CRD-C 104(Appendix A).

Table 7 Deleterious substances in fine aggregate

Material Percentage by Weight

Clay lumps and friable particles 1 . 0

Material finer than No. 200 sieve 3 . 0

Lightweight particles 0 . 5

Note: The total of all deleterious materials shall not exceed 3.0 percent of the weight of the aggregate.

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TM 5-822-7/AFM 88-6, Chap. 8

g. Aggregate for calibration hardstands. To avoidinclusion in the pavement concrete of iron oxides orother iron-rich materials having magnetic propertiesthat will interfere with the operation of the facility,the concrete aggregate proposed for paving calibrationhardstands will be subjected to detailed petrographicanalyses in accordance with ASTM C 295 prior toacceptance. Special attention will be given to theexistence of magnetite in granites, high-ironminerals in traprock, pyrite in limestone, and freeiron or iron oxide in slag aggregate. When a list ofaggregate sources is included in the contract specifi-cations, the sources not approved for concrete usedin calibration hardstands will be indicated.

h. Aggregate for power check pads. Concrete thatwill be exposed to extended jet engine blast duringmaintenance can use igneous rocks with a low silicacontent and a high content of ferromagnesianminerals or slag as aggregate to improve its perfor-mance under high temperature. Aggregates rich insilica such as quartzite or chert should be avoided.Aggregate with a high silica content such as sand-stone or granite, especially if coarse grained, cancause problems. Calcareous aggregates such as lime-stone or dolomite are acceptable.

6. Admixtures.a. Admixtures are used to modify properties of

fresh or hardened concrete. Admixtures may be usedto improve workability, control initial set, reduceheat generation, accelerate strength gain, increasestrength, and improve durability. Seven chemicaladmixtures are listed for use in portland cementconcrete in ASTM C 494, as follows: Type A—water-reducing admixture; Type B —retarding admixture;Type C–accelerating admixture; Type D–water-reducing and retarding admixture; Type E—water-reducing and accelerating admixture; Type F—water-reducing, high-range admixture; and TypeG–water-reducing, high-range and retardingadmixture.

b. Air-entraining admixtures provide resistanceto freezing and thawing and should meet therequirements of ASTM C 260, and will normally berequired in all concrete for pavements. For smalljobs under 1,600 cubic yards, air-entrainingcements may be considered. The use of any otheradmixture will depend on the economics of its useand site conditions. The effect of an admixture willvary, depending on conditions such as cement type,specific mixture proportions, ambient temperature,or water quality. Furthermore, an admixture may

affect several qualities of the concrete, and somedesirable properties may be adversely affected.Consequently, the decision to use an admixturemust be based on experience and tests with thecement, aggregates, and admixtures representativeof those to be used on the project. It must be demon-strated that the final concrete proposed pavementquality is not adversely affected by the use of anyproposed admixture. More extensive guidance onadmixtures is provided in ACI 212.lR and ACI212.2R.

7. Pozzolans.a. Pozzolans are defined in ASTM C 618 as

“siliceous or siliceous and aluminous materialswhich in themselves possess little or no cementitiousvalue, but will, in finely divided form and in thepresence of moisture, chemically react with calciumhydroxide at ordinary temperatures to formcompounds possessing cementitious properties.”This ASTM specification recognizes three classes ofpozzolan and provides detailed requirements foreach class. Class N pozzolans are raw or calcinednatural pozzolans such as some diatomaceous earths,opaline cherts, tuffs, volcanic ashes, clays, andshales. Fly ash is divided into two classes. Class F isfly ash produced by burning anthracite or bituminouscoal, and Class C fly ash is produced by burning ligniteor subbituminous coal. Environmental ProtectionAgency (EPA) guidelines published in 1983 (40CFR, Part 249) require that the use of fly ash mustbe allowed on all federal projects unless it can beproven technically unsuitable.

b. Pozzolans may be substituted for a maximumof 25 percent by volume of portland cement in concretefor pavements. If substitution of pozzolan abovethis limit is contemplated, a thorough test programmust show that the proposed substitution limit willnot adversely affect workability, admixture perfor-mance strength, and durability of the final concrete.Pozzolans typically have specific gravities appreciablylower than portland cement, and pozzolan limits areexpressed as a percent of the volume of cementitiousmaterials. In general, concrete containing pozzolanshas improved workability, lower heat of hydration,and a slower strength gain. When pozzolans are tobe used, the required time to gain the design strengthmay be increased beyond the standard 28 days forroads and streets and 90 days for airfield pavementsto the extent that the concrete is not to be exposedto traffic.

c. Class N pozzolans will not generally be

11

TM 5-822-7/AFM 88-6, Chap. 8

encountered in pavement construction. The use offly ash, however, is becoming increasingly common.Fly ash produced by industrial burning of coal tendsto be highly variable, depending on factors such asemission controls, load, and boiler design. Thisproduction variability is compounded further by thenatural variability of lignite and subbituminous coalthat produce Class C pozzolan. Also, Class Cpozzolans have poor resistance to sulfate attack,and some have high alkali contents that may contri-bute to alkali aggregate reaction. Specifications forpozzolans should require that the ASTM C 618specification be modified to require a maximum losson ignition of 6 and 8 percent, respectively, for ClassF and N pozzolans and a minimum pozzolanic activityindex with lime of 900 psi at 7 days. Mixture propor-tioning studies should use the same pozzolans andcements that will be used on the project and mustdetermine that the final concrete characteristics,strength gain, and durability are adequate.

8. Miscellaneous materials.a. Other materials used in concrete pavement

construction including curing materials, dowels, tiebars, reinforcement, and expansion-joint filler arecovered by applicable specifications. When concreteis required to be free of magnetic materials, specialinstructions will be obtained from HQDA (DAEN-ECE-G) for the selection of dowels, tie bars, andreinforcement. Aluminum will not be used in concretepavements.

b. Field welding of crossing bars (tack welding) isprohibited. All welded splices will conform to therequirements of the American Welding Society (AWS)D 1.4. Selection of the proper welding proceduredepends on the actual chemical composition of thesteel. A procedure suitable for one chemical compo-sition can be totally unsuited for another compositionof the same strength grade. It is essential that thecomposition of the steel to be welded be determinedbefore the welding procedure is established. Wherereinforcing bars are to be ordered for new work, thefabricator should be informed that welded splicesare contemplated. The fabricator can provide thechemical composition of the reinforcing bars and inmany cases can provide bars that are more suited towelding.

c. Epoxy-coated reinforcing steel and dowel barsare being used more frequently in areas such asbridge decks, coastal areas, and pavements subjectto heavy applications of de-icing salts to minimizepotential corrosion problems. If these materials are

used, they should conform to ASTM A 775. Epoxy-coated dowels and reinforcing steel will rest onepoxy-coated wire bar supports or on bar supportsmade of dielectric material. Wire bar supports willbe coated for a minimum of 2 inches from the pointof contact with the epoxy-coated reinforcing bars.Adequate ventilation to dissipate fumes must beprovided if epoxy-coated steel is welded.

d. Appendix C describes the materials andmethods used for the construction of steel fiberreinforced concrete.

9. Water. Water for mixing concrete will be free frommaterials that affect hydration of the cement.Potable water may be used without testing however,tests will be made in accordance with CRD-C 400 ifthe water source is a stream or another body ofwater of unknown quality. Seawater has been usedsuccessfully as mixing water, but this should onlybe done if there is no feasible alternative. There maybe up to a 15 percent loss in ultimate strength, settimes may be affected, and surface efflorescencemay occur. The risk of steel corrosion maybe increased,so the use of coated dowels and reinforcing steelshould be considered if seawater is to be used.

10. Sampling and testing of materials.a. Cement. Cement to be used in pavements for

aircraft traffic will be sampled and tested. Cementmeeting all other test requirements may be acceptedprior to the required 7-day age when the strength isequal to or greater than the 7-day strength require-ment. Cement for pavement projects requiring 1,600cubic yards or less of concrete may be accepted onthe basis of the manufacturer’s certified mill testreports showing compliance with cited cementspecifications.

b. Aggregates.(l.) Listed sources. Listing of aggregate sources

will be based on a thorough investigation to determinethat suitable aggregates are obtainable for theproposed use. Evaluation of the material will requirecomplete laboratory testing including petrographicexaminations, physical tests, durability tests, andalkali-reactivity tests. The service record of aggre-gates will be determined by inspecting structuresthat have had exposure equivalent to the proposedstructure. When an aggregate source has been listedpreviously for use on the basis of a complete investi-gation, additional similar use of the source within aperiod of 3 years may be permitted on the basis ofpetrographic examinations and limited physical

12

TM 5-822-7/AFM 88-6, Chap. 8

tests if the results show no change in the compositionand quality of aggregate. For proper design andpreparation of plans and specifications, it isnecessary to investigate and determine suitableaggregate sources and concrete strengths obtainablewith aggregates. It is essential that these investiga-tions be conducted as early as possible during projectplanning.

(2.) Sources for calibration hardstands. Whencontract specifications cover the paving of calibrationhardstands, the list of sources will indicate whichsources are approved for such work.

(3.) Aggregate sources not previously listed.When the contractor proposes aggregate from asource not previously listed, the evaluation ofsamples of that aggregate will include all testsnecessary to demonstrate that a concrete producedfrom the materials will have quality and strengthcomparable with that of concrete made with aggre-gate from the approved sources listed. When thecontracting officer is responsible for mixtureproportioning and cement is a separate pay item inthe contract, aggregates of good quality that requirean increase in the quantity of cement over thatrequired by aggregates from listed sources to produceconcrete of the specified flexural strength will beapproved for use only if the contractor agrees inwriting to pay for the additional cement required.

(4.) Unlisted source. When the contractspecifications do not include a list of approvedaggregate sources, the source(s) proposed by thecontractor will be investigated as soon as possibleafter the award of the contract.

(5.) Aggregates for a small project. Evaluationof aggregates from non-listed sources and concretemixture proportioning for projects requiring 1,600cubic yards or less of concrete, except for airfieldand heliport paving, will be performed by an approvedcommercial testing laboratory at no expense to theGovernment.

11. Delivery and storage of materials.a. Cement and pozzolan. Separate storage facilities

will be provided for each type of cementitiousmaterial. Storage facility will be thoroughly cleanedbefore changing the type of cementitious materialstored init. Storage facilities must be weather-tightand must be properly ventilated.

b. Aggregates.(l.) Control of grading. Aggregate-handling and

aggregate-storage facilities may vary greatly fordifferent projects, and only general requirements

can be specified. Grading and uniformity of gradingrequirements will be determined as the aggregatesare delivered to the mixer, and the contractor isresponsible for meeting these requirements. Carefulinspection of storage and handling operations,however, is desirable to assure satisfactory controlof the aggregate grading and to prevent contamin-ation by foreign material. Aggregate storage tech-niques that use coned piles or spread truck-dumpedaggregate with a bulldozer cause segregationproblems. Aggregates delivered by trucks are bestdumped and left in individual adjacent piles. A clamshell spreading aggregate in thin layers has alsobeen used to minimize segregation. Aggregateshould be handled as little as possible to minimizesegregation. Potential sources of contaminantsinclude windblown foundation and adjacentmaterials and contaminants from equipment used inhandling the aggregates.

(2.) Moisture control. Uniformity of freemoisture in aggregate is essential for proper controlof concrete consistency. A period of free-drainingstorage is required for fine aggregates and thesmaller size of coarse aggregate. Normally, 24 to 48hours will be sufficient. However, shorter or longertimes may be specified if the tests of time to reachan equilibrium so indicate.

12. Grade control. The lines and grades shown foreach airfield and heliport pavement category of thecontract shall be established and maintained bymeans of line and grade stakes placed at the jobsiteby the contractor. Elevations of all benchmarks usedby the contractor for controlling pavement operationsat the jobsite will be established and maintained bythe Government. The finished pavement grade linesand elevations shown shall be established andcontrolled at the jobsite in accordance with bench-mark elevations furnished by the contracting officer.The pavements shall be constructed to the thicknessesand elevations indicated. Provisions for line andgrade control for roads, streets, and open storageareas shall be included in the contract specifications.

13. Proportioning.a. Mixture proportioning. Before any concrete is

placed, trial mixtures will be prepared withmaterials from the sources to be used for productionof concrete on the project. When the contractor isresponsible for mixture proportioning, trial mixtureswill be prepared by a commercial testing laboratoryapproved by the contracting officer at no expense to

13

TM 5-822-7/AFM 88-6, Chap. 8

the Government, and the results will be submittedto the contracting officer for approval. When thecontracting officer is responsible for mixtureproportioning, trial mixtures will be prepared by theGovernment with materials supplied by the contractorfrom the sources to be used for production of concreteon the project. Mixtures will be made in sufficientnumber to establish optimum proportions of theaggregates and to represent a wide range in cementcontents and water–cement ratios within specifiedrequirements for air content and workability. Thewater-cement ratio will not exceed 0.45 by weightfor pavement mixtures. After the final proportionsof the trial mixtures have been established, 6–inchby 6-inch cross-section test/beam specimens fromeach mixture will be made in accordance withASTM C 192 and tested as described in ASTM C 78.A minimum of nine test specimens should be madeto establish the flexural strength of each mixture ateach test age. From these mixture proportioningstudies, the controlling maximum water-cementratio and hence the cement content required toproduce concrete of specified strength will be deter-mined. This same procedure will be used to establishnew mixture proportions when necessary because ofa change in the source or the character of the concreteingredients after concrete placement has started.

b. Mixture proportions.(l.) Contracting officer responsible for mixture

proportions. When the contracting officer is respon-sible for the mixture proportions, proportions of allmaterials used in the concrete mixture will be asdirected. The contracting officer will require suchchanges in the mixture proportions as necessary tomaintain the workability, strength, and qualityrequired by the contract specifications. The mixtureproportions determined by mixture proportioningstudies will be used in starting paving operations.Adjustments will be made by the contracting officeras necessary to establish the mixture proportionsbest suited for job conditions and materials used.Subsequent mixture adjustments will be made whennecessary, but usually these adjustments will be of aminor nature as required to compensate for variationsin gradings and the moisture content of the aggregate.

(2.) Contractor responsible for mixture propor-tions. When the contractor is responsible for themixture proportions, proportions of all materials usedin the concrete mixture will be as directed by thecontractor. The contractor will require such changesin the mixture proportions as necessary to maintainthe workability, strength, and quality required by

the contract specifications. The mixture proportions determined by mixture proportioning studies will beused in starting paving operations. Adjustmentswill be made by the contractor as necessary toestablish the mixture proportions best suited for thejob conditions and materials used. Project specifi-cations will require the contractor to notify thecontracting officer prior to making any change tothe approved mixture proportions and to indicatethe changes to be made. Changes to the mixtureproportions will be of a minor nature as required tocompensate for variations in gradings and themoisture content of the aggregate unless laboratorymixture studies for the new mixture are submittedfor approval.

c. Workability. The concrete slump shall not exceed2 inches. Within this maximum limit, the slump willbe maintained at the lowest practical value suitablefor prevailing weather conditions and for equipmentand methods used in placement of the concrete. Forsmall paved areas, slump in excess of 2 inches maybe permitted, but in no case will the slump exceed 3inches. The concrete slump will be determined in thefield by the method described in ASTM C 143. Slumpfor slipform paving of airfield and heliport pavementsshould be specified in a range of O to 1¼ inches.

d. Strength. Control of the strength of the concretemixture will be based on tests of concrete specimenstaken during the paving operations. Pavements tobe used by aircraft are designed on the basis of theflexural strength that the concrete is expected toattain at 90 days, and specimens will be tested atthis age for use in the evaluation pavements. Sincethe period necessary to obtain the 90-day fieldstrengths is too great to exercise proper control ofthe concrete during pavement construction, a 14-daystrength requirement will be included in the contractspecifications. Flexural-strength tests will be madeat 14 days to determine compliance with the 14-daystrength requirement. In addition, 7-day strengthtests will be made to provide an early indication ofthe concrete strength. The average strength at theage of 14 days of any five consecutive individual testvalues representing each concrete mixture will benot less than the specified strength at the age of 14days, and not more than 20 percent of the individualvalues will be less than the specified strength.Adjustments of the concrete mixture proportionswill be made as necessary to maintain this strengthcontrol. When sufficient 90-day strengths becomeavailable, further adjustment of the concrete mixturemay be made as necessary to assure that the 90-day

14

TM 5-822-7/AFM 88-6, Chap. 8

strength used for the design of the pavements will beobtained and that an economical mixture is being used.

14. Subgrade, base, forms, and string lines.a. General. The setting and protection of forms and

string lines and the final preparation of thesubgrade, base course, or filter course require closeattention to all details to assure that the pavementwill have the required thickness and the surface willbeat the required grade.

b. Subgrade. Subgrade is the natural soil or fillupon which the base and concrete pavement are placed.Special procedures may be necessary when dealingwith frost-susceptible soils, expansive soils, pumping-susceptible soils, lateritic soils, or organic soils.Removing soft or troublesome soils that occur inpockets may be desirable, where possible.

c. Base. A base may perform many functions, suchas drainage, construction platform, and structuralstrengthening of the pavement. A base may be agranular material or lime, cement, or an asphalt-stabilized material. Also a lean concrete, sometimesreferred to as “Econocrete,” is sometimes used as abase. There is no clearly accepted definition, butcement contents are typically lower, and sometimespoorer quality aggregates are used. The lean concretebase should meet the strength and durability require-ments of cement-stabilized materials and can betreated as a high-quality stabilized material indesign.

d. Form materials. Steel forms will be used for allformed pavement construction. Wood forms generallyare unsatisfactory for paving work, and their use willnot be permitted except for such miscellaneous areasas bulkheads and curved fillets. To avoid the excessivecost of pavement construction for small j ohs, woodforms may be allowed for pavements less than 8 inchesthick in noncritical areas, such as open storage areas,helicopter parking pads, and vehicle parking.

e. Construction of forms. Provisions relating tobuilt-up forms may be omitted from contract specifi-cations when the contract plans require constant slabdepth for each paved area. When this provision isretained in a contract specification, the contractor isrequired to furnish steel forms equal to the edgethickness of the majority of pavement slabs for eachpaved area. Built-up forms will be used only whereedge thicknesses exceed the basic form depth. Thebase width of built-up forms will be equal to thewidth required for a comparable full-depth form.Side forms on sl.ipform pavers will be the full depthof the pavement.

f. Placement of forms and string lines. Forms andstring lines should be installed well in advance ofconcrete paving operations so that the requiredchecks and necessary corrections can be madewithout stopping or hindering concrete placement.The same reasoning applies to the final preparationof the underlying material, which should not be lessthan one full day’s operation of the paving equip-ment ahead of paving.

g. String line. The string line will be of high-strength cord or wire. The choice will depend on thetype of automatically controlled slipform paver used.Certain manufacturers recommend that high-tensile-strength wire be stretched tautly between supports.Other manufacturers recommend a large-diametercord and do not require the tautness that is recom-mended for the wire. The use of wire requires firmlyanchored supports. As a result, the wire is less likelyto be disturbed than is the cord whose supports donot have to be so firmly anchored. The wire isdifficult to see, and flagging should be attachedbetween the supports to reduce the chance that itwill be disturbed during construction. The cord doesnot require supports to be as firmly anchored as forthe wire, and as a result, the cord is easier to installand maintain. However, the chance of sagging betweenthe supports is greater. The cord is easy to see, andas a result, the chances of its being knocked out ofalinement are less than for the wire. However, thecord is more easily disturbed than the wire andshould be checked frequently.

h. Removal of forms. Pavement forms generallymay be removed 12 hours after the concrete is placed.A longer period will be necessary when the strengthgain of the concrete is retarded because of delayed orinadequate protection during cold weather. In someinstances, earlier removal of forms maybe permittedso that the transverse joints may be sawed completelythrough to the edge of the slab without leaving asmall fillet of concrete adjacent to the form.

15. Batching and mixing.a. General. There are three types of plants: auto-

matic, semi-automatic, and manual. For pavingprojects, either automatic or semi-automatic plantswill be acceptable. Specifications will be prepared toallow either type of plant, and the contractor willhave the option as to the type of plant to be used.

b. Plant capacity. The capacity to be specified forthe batching plant and mixing equipment will bedetermined in accordance with the concrete-placementrequirements for the project. Since the pavement

15

TM 5-822-7/AFM 88-6, Chap. 8

slabs are comparatively small, the plant capacitygenerally will not be influenced by any requirementsfor maintaining the concrete in a plastic conditionduring placement. The main considerations will bethe required placing schedule to meet the completiondate for the construction or, when slipform paversare used, the required amount of concrete to maintaina uniform forward movement of the paver of not lessthan 2.5 feet per minute. However, the placementrate specified for pavements constructed during hotweather should also be considered in determiningplant capacity requirements.

c. Concrete mixers. Mixers having a capacity of at least 5 cubic yards of mixed concrete are required forairfield paving projects, but smaller mixers may bepermitted for small road projects and other smallmiscellaneous construction. Contract specificationsfor jobs of suitable size and location will include anoption for the contractor to reduce mixing time duringprogress of work from the mixing time required atthe start of the job on the basis of mixer performancetests in accordance with CRD-C 55, provided thefollowing requirements are met at all times:

Weight per cubic foot of mortar calculated to an air-free basis, lb/ft3

Air content, volume percent of concrete

Slump, inches

Coarse aggregate content, portion by weight of eachsample retained on No. 4 sieve, percent

Average compressive strength at 7 days for eachsample based on average strength of all test speci-mens, percent 10.0

Water content, portion by weight of each samplepassing No. 4 sieve, percent 1.0

Parameters Tested For: Requirement, expressed as maximum permissiblerange in results of tests of samples taken from threelocations in the concrete batch

1.0

1.0

1.0

6.0

In addition, no reduction in mixing time will beallowed if it results in a reduction in the 7-dayflexural strength from the average strength of fiveconsecutive sets of specimens made from batchesmixed the full time. The requirements for stationarymixers and truck mixers will be included unless it isdetermined that concrete complying with the specifi-cations cannot be manufactured by these types ofmixers. Truck mixers often have difficulty indischarging the comparatively low-slump concretemixtures required for airfield pavement construction,therefore, truck mixers should comply with ASTM C94. The tendency of the concrete to hang up indischarge chutes may cause delays, which frequentlylead to requests by the contractor that the concreteslump be increased. This difficulty also may occurwith vehicles used for hauling concrete to formswhen stationary mixers are used. The slump ofready-mix concrete will not be increased because of

16

the inadequacy of the mixing or transportationequipment to mix and discharge the concrete.

d. Approval of mixers. Before truck mixers orstationary mixers are approved for use, carefulconsideration will be given to the proposed plant andfacilities for storage and handling of materials, andfor batching, mixing, transporting, and handling ofconcrete at the jobsite to assure that adequate controlof the concrete can be exercised. When truck mixersare used with a long haul between the batching plantand the project, adequate control of the concretemay be difficult due to variations in slump and aircontent caused by differences in mixing time. Insuch cases, it will be necessary to require that mixingbe done after the mixer trucks arrive on the job.Truck mixers will not be permitted for mixing concreteon slipform construction. Truck mixers shall beequipped with accurate revolution counters. Ingeneral, truck mixers should only be used on jobs

TM 5-822-7/AFM 88-6, Chap. 8

requiring 2,500 cubic yards of concrete or less.e. Transporting plant-mixed concrete. Vehicles for

transporting concrete from stationary mixers to theforms will conform to the applicable requirements ofASTM C 94. Plant-mixed concrete may be trans-ported in a truck agitator, in a truck mixer operatingat agitating speed, or in approved non-agitatingequipment. Non-agitating equipment will havesmooth, watertight, metal bodies equipped withgates to permit control of the discharge of theconcrete; covers will be provided for protectingconcrete in transit, as required. Concrete transportedin non-agitating equipment will be discharged intothe pavement forms or to the slipform paver within45 minutes after introduction of the mixing waterand cement to the aggregates at the mixer. Themajor problem in using ready-mixed concrete inpavement construction is avoiding segregation indischarging and transferring the concrete from thetransporting unit to the final position in the form oron the subgrade in front of the slipform paver. Theuse of ready–mixed concrete requires suitabletransfer and spreading equipment capable ofdepositing and distributing the concrete in anunsegregated condition in the final position in theforms. When low-slump plant-mixed concrete istransported, trucks equipped with vibrators areoften required to discharge the concrete and shouldbe required unless it is satisfactorily demonstratedthat the concrete can be discharged without delay.

16. Placing.a. General. Concrete may be placed between fixed

forms or using approved slipform paving equipment.Both methods produce satisfactory results, andwhen possible, the option should be left with thecontractor as to the method to be used. Withslipform equipment, the rate of placement can besignificantly increased over the rate with fixedforms. In addition, the material for forms and thelabor for setting forms are eliminated. As a result,the cost for large jobs will be less for slipform place-ment than for placement with fixed forms. However,on small jobs or larger jobs with special requirements,the use of fixed forms may be necessary or may bemore economical than the use of slipform equipment.No guidelines can be given as to what size job willpermit the economic use of slipform pavers.

b. Placing time. Concrete will be placed beforeobtaining its initial set and within 45 minutes aftercement has been added to the batch. These provisions

apply to all paving projects regardless of the type ofmixing equipment used. The addition of water to themixture in excess of that required by the mixtureproportions to maintain slump during prolongedmixing will not be permitted.

c. Slipform paving. Approval of the slipform pavingequipment for airfield pavement will be based on satis-factory performance in the field. Trial sections ofsufficient length and located in low-volume aircrafttraffic areas will be used to approve the paving equip-ment, considering both slipform and another for thefill-in operation when scheduled by the contractor.Furthermore, approval shall be based on the abilityof the machine to consolidate the concrete and formthe pavement to the desired cross sections. Plangrade and surface smoothness tolerances must bemet. Particular attention should be paid to the abilityof the machine to form the required edge withoutexcessive slumping or tearing during slipform opera-tions and to form a suitable longitudinal constructionjoint during fill-in operations. The machine shall notdamage the surface or edge of the previously placedslab during fill-in operations. The suggested lengthof the trial section is 1,000 to 2,000 feet. Slipformpavers with a full-width auger are recommended.Traveling blades have been less satisfactory. If theslipformed pavement is 10 inches or greater inthickness, some of the lighter slipform pavers mayhave problems properly handling the low-slumpconcrete.

d. Spreading. Hand spreading of concrete will bepermitted only when necessitated by odd widths orshapes of slabs, or in emergencies such as equipmentbreakdown.

e. Vibration. Vibration requirements are influencedby many factors, such as the type and size of aggre-gate, mixture proportions, air entrainment, slump,workability of mixture, and pavement thickness.The specified maximum spacing for vibrator unitsand the specified vibrating procedures are based onfield experience with the vibration of pavements 12inches or more in thickness. There has been onlylimited use of internal vibration for thinner slabs. Ifnecessary for proper consolidation of the concrete, acloser spacing of vibrator units will be required.Particular attention should be paid to vibratorsalong the edge of the paving lane to ensure that theedge is properly consolidated. General experiencehas been that it is more satisfactory to use vibratorsat a closer spacing and for shorter periods of vibra-tion than to attempt to consolidate the concrete byprolonged vibration at a wider spacing. The duration

TM 5-822-7/AFM 88-6, Chap. 8

of the vibration will be limited by the time necessaryto produce a satisfactory consolidation of theconcrete, and over-vibration will not be permitted.Vibrators must not be permitted to touch forms,dowels, tie bars, or other embedded items.

f. Surface vibrators. Surface vibrators will not bepermitted because past experience with them hasbeen generally unsatisfactory. Surface vibrationtends to bring excess fine material and water to thesurface, which in many instances contributes tosurface deterioration and scaling. Surface-vibratorpans also tend to ride on high places in the concretesurface and thus cause non-uniform consolidation ofthe concrete.

g. Steel reinforcement. Project drawings will showtypical details of all slab reinforcement and willindicate the pavements requiring reinforcement andthe location and amount of steel required in theslabs. This information will supplement the specifi-cation requirements for reinforcement, and allrequirements will be carefully checked to insure nodiscrepancies between drawings and specificationrequirements.

h. Placing during cold weather. Pavement concreteshould not be placed when the air temperature isbelow 40 degrees F. If unusual job conditions requireconstruction at these low temperatures, specialprovisions for placement and protection of theconcrete will be needed. For additional informationon winter concreting, refer to ACI 306R. Thenecessary covers and other means of protecting theconcrete during cold weather should be available onthe job before starting concrete placement. Calciumchloride as an admixture may be either required orapproved to accelerate the setting time of concreteplaced during cold weather. No changes will be madein the requirements for temperature of the concretewhen placing or for protection of the concrete

against freezing when calcium chloride or any other accelerator is used.

i. Placing during hot weather. During hot weatherspecial precautions are necessary to prevent theformation of plastic-shrinkage cracks which resultfrom an excessive loss of moisture from the concretebefore curing is begun. The concrete needs to be placedat the coolest temperature practicable, and in no caseshould the temperature of the concrete as placedexceed 90 degrees F. Mixing and placing of concretewill be controlled to keep moisture loss at aminimum. Aggregates will be moist when added tothe mixer, and the subgrade dampened so it will notabsorb water from the concrete. The temperature ofthe concrete may be reduced by using cement with alower temperature by sprinkling the stockpiles ofaggregate to produce cooling by evaporation, by pre-cooking mixing water and by avoiding delays in mixingand placing concrete. The concrete needs to be placedand finished as rapidly as practicable, and the curingstarted without delay. If the application of the curingmedium should for any reason lag placement for atime sufficient to permit surface drying, the surfaceshould be kept damp with a fog spray, and placementshould be discontinued until corrective action can betaken. The fog spray equipment will be capable of applying a very fine mist to the concrete to replacemoisture lost by evaporation. In windy areas,screens may be needed to protect the concrete fromrapid evaporation caused by wind. Steps shall betaken to avoid an evaporation rate in excess of 0.2pound per square foot per hour as shown in figure 1.This is adequate for most conditions, but there arereports of plastic-shrinkage cracking occurringunder adverse conditions when the indicated evapor-ation rate was as low as 0.15 pound per square footper hour. Additional information is available in ACI305R.

18

TM 5-822-7/AFM 88-6, Chap. 8

Figure 1. Prediction of concrete rate of evaporation

(From “Curing of Concrete,” Concrete Information Sheet,

5.0

4.0

3.0aI

%

3

2.0 y

1.0

0

1966, with permission of the Portland Cement Association,Skokie, IL. )

19

TM 5-822-7/AFM 88-6, Chap. 8

j. Placing of small areas. For vehicular parking andpaving projects of 1,600 cubic yards or less, machinespreading, finishing, and floating will not be requiredif the benefits derived from the use of the equipmentare not commensurate with the cost of using themachines. In this case, hand spreading, finishing,and floating will be specified.

k. Overlay pavement construction.(l.) General. Where overlay pavement construction

is required, contract specifications will containspecial provisions for preparation and treatment ofthe existing surface before placing concrete in theoverlay pavement. Criteria herein pertain toconstruction of rigid overlays on existing rigidpavement. Construction of rigid overlays on existingflexible pavement or on existing rigid pavement witha bond breaking course is treated as new construction.Construction of thin bonded overlays is discussed inappendix B.

(2.) Bond between layers of pavement. Overlaypavements generally are designed on the assumptionthat a partial bond will develop between the twoconcrete layers. Concrete surfaces to receive partiallybonded overlays will be thoroughly cleaned of dirtand other foreign material, loose or spalled concrete,extruding joint seal, bituminous patches, andmaterial that would break the bond between theconcrete layers. Different areas of pavement willrequire different treatment. The condition of theexisting pavement will determine the cleanupmeasures necessary. Normally, sandblasting orsurface-abrading equipment will be required toremove material adhering to the surface, and handscaling of loose or spalled material will be required.No special treatment such as an acid wash of theprepared surface or the use of a grout bonding coursewill be required for partially bonded overlays. Inareas where oil or grease is present on the surface,scrubbing with a detergent and a wire brush may berequired. Cleaning of surfaces to receive the overlaywith rotary grinding equipment will be permitted,but the surface must be swept clean prior to placingthe concrete overlay.

(3.) Control of cracking in overlay pavements.Considerable difficulty has been experienced withuncontrolled cracking of overlay pavements atcontraction joints. This cracking is likely to occurduring hot weather when the temperature of theexisting pavement is appreciably higher than that ofthe concrete being placed in the overlay. Contractiondue to cooling of the base pavement results in move-ment at the existing joint, which may start a crack in

20

the bottom of the overlay as the concrete hardens.This cracking may occur when the concrete is toogreen to saw. Often the crack is not visible at thesurface of the pavement when the sawing is done. Toprevent such cracking, it may be necessary to useinserts in the plastic concrete to form contractionjoints.

1. Control of cracking in pavements placed on leanconcrete and cement-stabilized bases. Occasionalproblems have developed when relatively thinconcrete pavement has been placed directly on leanconcrete bases or stabilized bases with high cementcontents. Uncontrolled contraction cracks in thebase material have on occasion reflected through thenew pavement. If a thin pavement less than 9 inchesthick is to be placed directly on a cement-stabilizedor lean concrete base, it may be desirable to eitherplace a bond-breaking material between the pave-ment and base or to saw cut contraction joints in thebase to match those in the pavement surface. If abond breaker is used between the pavement surfaceand the base, the design engineer must be aware ofthe lack of bond since this can affect the requireddesign thickness of pavement. If contraction jointsare to be sawed in the base to control cracking, itmust be done at an early age just as discussed inparagraph 22d for concrete pavements.

m. Appendix D describes the methods and pro-cedures for the construction of roller compactedconcrete pavements.

17. Field test specimens.a. General. Field tests other than those called for

by contractor quality control will be conducted bythe Government to determine the slump and aircontent of freshly mixed concrete, and specimenswill be molded to test for flexural strength of hardenedconcrete. All tests will be performed under the super-vision of the contracting officer. However, since thecontractor will be required to furnish concretesamples, labor, and facilities for molding and curingtest specimens, specifications must indicate theextent of testing required. Equipment for makingair-content and slump tests will be furnished by thecontracting officer when the Government is respon-sible for testing and by the contractor when thecontractor is responsible for testing. Beam moldswill be made of steel and will be rigid and watertight.Beam molds will be supplied by the contractingofficer except when the contractor is responsible fortesting. When molds are required to be furnished bythe contractor, details necessary to assure that the

TM 5-822-7/AFM 88-6, Chap. 8

molds furnished are satisfactory will bein the contract specifications.

b. Specimens for strength tests. Test

inc luded

specimensfor determining conformance with specified strengthrequirements will be moist-cured under fieldlaboratory conditions. The size and number of curingtanks will depend on the number of specimens takenand the “ages at which the tests are made. For airfieldpaving projects, flexural-strength tests will beconducted at the ages of 7, 14, and 90 days. For otherpavements, designed on the basis of 28-day flexuralstrengths, the test ages will be 7, 14, and 28 days.Where 90-day flexural strength tests are required,provision will be made for curing and testing ofspecimens after the project is completed.

c. Specimens for determining time of openingpavement to construction traffic. Ordinarily, nofield-cured specimens will be required. However, forcold-weather construction when field-strength datamay be necessary to permit the opening of the pave-ment or portions thereof to construction traffic priorto 14 days, test groups of at least three beams shallbe taken, as required, from concrete placed indesignated areas. The beams of each test group shallbe made from a single batch of concrete and shall becured in accordance with ASTM C 31.

18. Finishing.a. Equipment and methods. Types of finishing

equipment other than conventional equipment maybe used on a trial basis when capable of finishingconcrete of the quality and consistency required.Equipment that fails under trial to perform in asatisfactory manner will be rejected and removedfrom the work area.

b. Surface finishing and testing. Finishing opera-tions are designed to obtain a dense, smooth surfacetrue to the required grade. Since the surface receivesthe greatest exposure to weathering and traffic,every precaution will be taken to obtain a high-qualityconcrete at the surface. The finishing operations willbe kept to the minimum necessary to obtain therequired surface finish. Excessive surface manipula-tion will not be permitted because it tends to bring asurplus of mortar, water, and undesirable softmaterials to the surface which contributes to scalingand surface deterioration. Finishing should leave thesurface at the proper grade. If the mechanicalfinishing operations are properly controlled, very littlehand finishing will be necessary. Short floats will beused only as necessary to correct local surfaceuneveness. Straightedges of the required length will

be used primarily to smooth and check the surface.To avoid later costly corrections of hardened pave-ment which fails to conform with specified surfacetolerances, the surface will be thoroughly checkedduring the mechanical floating, and necessarycorrections will be made.

c. Hand finishing and edging. Machine finishing isrequired, and hand finishing is only permitted forodd widths and shapes of slabs, areas adjacent toheaders, and areas around outlets in the pavements.Hand-finished areas will have the same quality andthe same surface characteristics as those areas finishedby machine. Hand finishing along the edges of slip-formed lanes to correct edge slumping or to repairareas damaged by tearing or sloughing shall be heldto a minimum. The only manipulation permittedalong the edges of slipformed lanes shall not disturbthe edge or use the edging tools to correct deficienciesin the edge.

d. Surface texture. The final surface texture of thepavement will be provided by means of a burlapdrag, broom, artificial turf, wire comb, or grooving.Dragging the surface of the concrete in the directionof concrete placement with moist burlap leaves a finesandy surface that is adequate for low-speed traffic.At least 2 feet of burlap must be in contact with theconcrete, and the burlap should be cleaned asnecessary. An improved skid-resistant surface canbe produced with a broom consisting of multiplerows of stiff bristles capable of producing serrations1/16 to1/8 of an inch deep. The brooms will have to becleaned frequently during texturing. Artificial turfhas been used successfully for texturing concrete.This is applied in the same manner as the burlap withat least 2 feet of the artificial turf in contact with theconcrete. One artificial turf that has provided asatisfactory texture consisted of 7,200 polyethyleneturf blades approximately 0.85 inch long per squarefoot. The wire comb provides the most skid-resistanttexture of the finishing techniques described so far.However, it is also the most difficult to use andadjustments to the concrete proportions may have tobe made to find a mixture that can be wire-combedwithout objectionable surface tearing. The wirecomb should consist of flexible spring steel linesspaced not less than 1/2 inch nor more than 1 inchapart. Closer spacing causes problems with raveling,and wider spacing results in objectionable roadnoise. The serrations left by the steel lines should beabout 1/8 to 1/4 inch deep and 1/16 to 1/8 inch wide. A singlepass of burlap or artificial turf can be made beforethe wire comb if desired. Because of problems with

21

TM 5-822-7/AFM 88-6, Chap. 8

skid resistance for aircraft traveling at high speed,the Air Force requires that new runways have aburlap drag finish with saw-cut grooves. Figure 2shows the grooving requirements for an Air Forcerunway. If the constructed pavement surface texture

Figure 2. Air Force runway

is inadequate due to poor texturing techniques, rain-fall on insufficiently hardened concrete, or othercauses, grooving or grinding will restore the skidresistance of the surface.

grooving requirements.

22

TM 5-822-7/AFM 88-6, Chap. 8

19. Curing.a. Control of cracking. Plastic shrinkage (craze)

cracking is caused by a combination of (1) highambient air temperature, (2) high concretetemperature, (3) low relative humidity, and (4) windvelocity. These conditions need to be controlledwhen placing and protecting young concrete. It isessential that concrete be protected against the 10SS

of moisture and rapid temperature change for thespecified period of protection. All equipment,material, and supplies for adequate curing andprotection of the concrete must be on hand and readyto install before actual concrete placement begins. Ingeneral, curing will be accomplished by using apigmented membrane-curing compound. However,other methods may be specified if indicated by localconditions.

b. Membrane curing. The curing compound will beapplied by means of a power-driven machinestraddling the newly paved lane and operated so thatthe spray will cover the pavement surface completelyand uniformly. Spray nozzles must be surrounded bya hood to prevent wind from blowing the curing–compound spray. The rate of advance and spacing ofnozzles of the spraying machine will be controlled sothat a two-coat overlapping coverage will be provided.Hand-operated pressure sprayers will be permittedonly on indicated odd widths and shapes of slabs andon concrete surfaces exposed by removal of forms.The curing compound must form a continuous void-

free membrane and be maintained in this conditionthroughout the curing period. Unsatisfactory ordamaged areas will be resprayed. Any damage to themembrane during the sawing operation will becorrected by respraying. When forms are removed,the exposed faces of the concrete will be sprayedwith curing compound.

c. Substituting curing provisions. Where it hasbeen established from past experience in an area thatmembrane curing alone does not adequately protectpavement from shrinkage cracking, a combination ofmoist curing and membrane curing may be specified.

d. Selection of curing material for pavements to bepainted. In selecting curing material for pavementsurfaces to be painted, consideration will be given tothe necessity of sandblasting to remove coatings anddeposits that interfere with the bonding of paint.Curing compounds of the low-melting-point wax-base type tend to penetrate concrete and should notbe used in the areas to be painted.

20. Grade and surface-smoothness requirements.a. Heliport and airfield pavements. The specified

grade and smoothness requirements applicable toairfield and heliport pavements are shown in table 8.The finished surfaces of airfield and heliportpavements shall have no abrupt change of 1/8 inch ormore and shall not deviate from the testing edge ofan approved 12-foot straightedge more than thetolerances shown in table 8.

Table 8. Surface smoothness - airfield and heliport pavements

Direction TolerancesItem No. Pavement Category of Testing inches

1 Runways and taxiways

2

3

Calibration hardstands and compassswinging bases

Other airfield and heliport areas

b. Road, street, and open-storage concretepavements. Pavements shall be smooth and true tograde and cross section. When tested with a 10-footstraightedge on lines 5 feet apart parallel with thecenterline of the pavement, the surface shall not varymore than 1/8 inch from the testing edge of thestraightedge.

Longitudinal 1/8Transverse 1/4

Longitudinal 1/8Transverse 1/8

Longitudinal 1/4Transverse 1/4

c. Requirements for other vehicular pavements.Parking area, motor-pool and motor-storage area,repair- yard, and open-storage area pavements shallbe smooth and true to grade and cross section. Whentested with a 10-foot straightedge on lines 5 feetapart parallel with and at right angles to the center-line of the paved area, the surface shall vary not more

23

TM 5-822-7/AFM 88-6, Chap. 8

than 1/4 inch from the testing edge of the straightedge.d. Slipform paving edge slump. Edge slump is the

downward movement of the plastic concrete thatoccurs when the sliding form passes. Excessiveslump is indicative of improper concrete mixtureproportioning. If the concrete mixture cannot beredesigned to overcome the edge slump problem, fixedform paving should be used. When slipform pavingis used, 85 percent of the pavement will not have anedge slump exceeding 1/4, inch, and 100 percent of thepavement will not have an edge slump exceeding 3/8 ofan inch. The area of pavement affected by this slumpwill be limited to the outer 18 inches adjacent to theslab edge.

21. Tolerances in pavement thickness. Pavement willbe constructed to thicknesses indicated, and pave-ment thickness will be checked by measurements ofcores drilled from the pavement as required by thecontracting officer. Cores generally will be taken atintervals of 2,000 feet or a fraction thereof from eachpavement lane of paved area where the lanes are1,000 feet or more in length and from every otherlane of the paved area where the lanes are less than1,000 feet in length. Additional core drilling todetermine the extent of a pavement area deficient inthickness will be included in the contract specification.Cores for checking pavement thickness will have adiameter of no less than 4 inches. When cores areused for compressive-strength or splitting tensile-strength tests (ASTM C 496) as well as for checkingpavement thickness, a 6-inch-diameter core will bedrilled. Drilling and measurements of cores forchecking pavement thickness will be done by theGovernment. Costs of drilling and testing additionalcores requested by the contractor will be borne bythe contractor. When the contractor is required tocut cores to check pavement thickness, additionalcore drilling requirements will be included in thecontract specification. All core measurements will bemade by the contracting officer, and the cores willbecome Government property.

22. Repairs of defective pavement slabs. Groovingand sealing or epoxy sealing of random cracks, fillingof non-working contraction joints, repairing ofspans along joints and cracks, and removing andreplacing of broken slabs that occur in non-reinforcedconcrete pavements during construction will beaccomplished according to the requirements in thecontract specification. Additional and supplementalinformation is provided in TM 5-822-9. Areas not

meeting smoothness and grade requirements will berepaired or replaced. High areas can be reduced byrubbing the freshly finished concrete with carborun-dum brick and water within 36 hours of the concreteplacement or by grinding the surface after it is 36hours old. Generally, grinding should not exceed 1/4inch in depth. The final surface of the repaired areamust retain the required skid resistance of the sur-rounding pavement.

23. Joints.a. General. Joints are constructed in concrete

pavement to permit contraction and expansion of apavement without irregular cracking and as aconstruction expedient to separate the paved areainto strips necessary for handling and placing ofconcrete. There are three general types of joints:construction, expansion, and contraction.

b. Construction joints.(l.) Longitudinal construction joints. These

joints formed between paving lanes at the spacingindicated will be either thickened edge, keyed, keyedand tied, or doweled. The dimensions of the keyedjoint are critical. It is essential that both key dimen-sions and the location of the key in the joint conformwith details on drawings. Key dimensions are basedon pavement thickness with each thickness requiringa different key size. When stationary forms are used,metal molds for forming the keyway will be securelyfastened to the concrete forms so that molds will notbe displaced by paving operations. When slipformpavers are used to form keyed joints, the keywayshall be formed by means of pre-formed metalkeyway liners, which are inserted during paving. Themetal liners may be shaped as they are fed throughthe paver from continuous strips, or they may bepre-formed sections bolted together before insertionthrough the paver. It is recommended that the metalliners be left in place. When slipform pavers are usedto form keyed and tied joints, bent tie bars shall beinserted into the plastic unconsolidated concretethrough a metal keyway liner as described above.The tie bars shall be straightened after the concretehas hardened. The bent bars should be inspected toinsure that the radius of curvature at the bend isequal to or greater than the specified minimumradius of curvature for the grade of steel being used.When stationary forms are used, all dowels will beplaced by the bonded-in-place method. Either one-piece dowels or split dowels of the threaded type willbe used. Dowels will be held accurately and securelyin place by fastening to the forms. When slipform

24

TM 5-822-7/AFM 88-6, Chap. 8

pavers are used, dowels shall be placed by bondingthe dowels into holes drilled into the hardenedconcrete with rotary core-type drills that can bemaintained in a position parallel to the surface of thepavement and perpendicular to the face of the edgeof the slab in a longitudinal direction. Some low impactenergy hydraulic and electro-pneumatic drills havebeen used to successfully drill dowel holes withoutspalling the concrete. These and similar types ofdrills can be allowed if the contractor is able tosatisfactorily drill the specified holes without unduespalling around the hole. The diameter of the holeshould be larger than the diameter of the dowel barbut should not be more than 1/8 inch larger than thediameter of the dowel bar. The contractor will berequired to demonstrate to the contracting officerthat the dowels can be securely bonded and properalinement can be attained. Continuous inspectionwill be required thereafter to insure that the dowelsare securely bonded and that they are alined properlyboth horizontally and vertically. The method used forinserting the epoxy-resin grout into the hole shallplace sufficient grout to completely anchor the dowel.

(2.) Transverse construction joints. When concreteplacement is stopped or interrupted for 30 minutesor longer, these joints are installed across the pave-ment lane. Insofar as practicable, these joints will beinstalled at the location of a planned joint.

c. Expansion joints. When expansion joints arerequired within a pavement, joint assembliessupporting both joint filler and dowels will beinstalled before placing concrete. Accurate locationand alinement of joint filler and dowels are necessaryfor proper functioning of joints. Since checking ofembedded items in joints installed within a pavinglane is extremely difficult, it is essential thatassemblies used for supporting embedded items berigidly constructed and capable of resisting all move-ment and distortion during paving operations. Greatcare and continuous inspection are required duringplacing and finishing of concrete near joints to avoiddisplacement of joint filler and dowels. Additionalhand vibration will be required around the jointassemblies to insure adequate consolidation. Thecontractor is required to provide a template forchecking the position of the dowels.

d. Contraction joints.(l.) General. Contraction joints use a groove to

form a weakened plane in the concrete, as the concreteundergoes shrinkage, a fracture forms through theconcrete below the groove. Load transfer is providedby aggregate interlock in the fracture plane below

the joint groove or by an aggregate interlock anddowels. Where dowels are required across transversecontraction joints, suitable dowel-supportingassemblies will be used and care taken to assure properalinement of dowels in the completed pavement.Requirements for dowel supports have been discussedin c above. Where tie bars are required in longitudinalcontraction joints, suitable supporting devices willbe provided for holding tie bars in place during pavingoperations, or the bars may be installed in front ofthe paver by insertion into the unconsolidated,freshly placed concrete. The device for inserting thebars shall be mounted on the paver and will auto-matically insert the bars to the specified depth andat the required spacing.

(2.) Joint types. Contraction joints may beconstructed by sawing a groove in hardened concreteor installing a suitable insert in freshly placedconcrete. Inserts will not be used on airfieldpavements without the prior approval of AFESC.Sawing of joints eliminates manipulation of freshlyplaced concrete after placement and provides thebest conditions for obtaining a smooth surface at thejoint. However, sawing time is critical, and crackingwill occur at the wrong place if the joints are notsawed at the proper time. The filler-type joint formsa weakened plane in the freshly placed concrete,which induces fracturing of concrete at the joint,permits continuous curing of pavement, and providesprotection for the joint until removed or depressed inpreparation for the sealing of joints. Although sawedjoints have been used successfully on many projects,excessive cracking has occurred in some instances.This is usually due to delayed sawing. When sawingcannot be accomplished without undue uncontrolledcracking due to unusual conditions, provisions shallbe made for using inserts. Filler-type joints maybeapproved for longitudinal contraction joints when itis demonstrated that these joints can be properlyinstalled with vibratory equipment. The filler mustbe maintained in a vertical position and in properalinement in the finished pavement.

(3.) Installation of insert-type joints. Insert-type joints will be installed immediately after allmachine finishing operations are completed. Themacine for installing the insert shall have a vibratorybar that cuts a groove in concrete and simultaneouslyinstalled an insert in required locations. The intensityof vibration on the bar will be variable as necessaryto form the groove in the freshly mixed concrete andto consolidate the concrete around the insert after itis in place. Inserts must be the proper depth for the

25

TM 5-822-7/AFM 88-6, Chap. 8

concrete being placed because the load transferbetween the slabs depends on the interlock of aggre-gate below the formed portion of the joint andmaterial that is not deep enough will not producecracking at the proper location. Insert material mustbe placed flush with the surface to not more than 1/8inch below the surface. The surface of the pavementwill be finished with a vibratory float; hand floatingwill not be permitted. When finishing concrete afterinstallation of the insert, an excessive amount of finematerial must not be worked to the surface and adja-cent to the insert. Excessive fines will cause scalingof the surface and spalling of the joint.

(4.) Sawing of transverse contraction joints.(a.) Method. Transverse and longitudinal

contraction joints shall be constructed to conformwith details and dimensions indicated. Saw cutsshall be made to the depth indicated to insure thatcracking occurs as planned. Joints shall be constructedby sawing a groove in the hardened concrete with apower-driven saw.

(b.) Time. No definite time for sawing jointscan be specified because of the many factors thatmay influence the rate of hardening of concrete suchas air and concrete temperatures during placement,ambient temperatures, weather conditions, curingand protection, cement content, and mix character-istics. The basic rule for satisfactory sawing is: “Beprepared to saw as soon as the concrete is ready forsawing regardless of the time of day or night. ”During warm weather, when most pavements areconstructed, the concrete usually will be ready forsawing about 6 to 12 hours after placing. Sinceconcrete is placed mainly during daylight hours, alarge portion of sawing will have to be done at night,and adequate lighting must be provided for thispurpose. Although a clean, sharp cut is desirable, asmall amount of raveling at the top of the saw cut isnot objectionable when early sawing is necessary to

avoid uncontrolled cracking. Sawing too early,however, will be guarded against to preventexcessive washing and undercutting of concrete inthe joint. The proper time for sawing the joints willbe determined for prevailing conditions on the jobduring each concrete placement. Since conditionsmay change from day to day, it is essential that thesaw operator be experienced in sawing pavementjoints.

(c.) Sawing sequence. Transverse joints will besawed consecutively in the same sequence as theconcrete is placed in the lane. Sawing of alternatejoints in the pavement is undesirable becauseconcrete tends to tear ahead of the saw cut whenintermediate joints are sawed. This procedure alsoreduces the uniformity of fracturing of joints, whichmay result in excessive opening at some joints.Before sawing each joint, the concrete will beexamined closely for cracks, and the joints will notbe sawed if a crack has occurred near the joint.Sawing will be discontinued in any joint where acrack develops ahead of the saw cut.

(d.) Cuts. All areas of curing compound damagedby the sawing operation will be resprayed. A cordwill be placed in the saw cut to retard evaporation ofmoisture.

e. Special joints. The special joint shown in figure 3for placing new concrete pavement adjacent to oldconcrete pavement requires special care. The concreteplaced under the old pavement must be thoroughlyvibrated and must not be placed too rapidly or airvoids will form under the old pavement. Use of awater-reducing admixture to improve workabilitymay be helpful. Proper construction of this jointrequires special inspection of construction technique.An alternate method of providing a load-transferringjoint when abutting old and new concrete pavementsis to drill and grout dowel bars into the vertical faceof the old pavement.

TM 5-822-7/AFM 88-6, Chap. 8

Figure 3. Special joint between new and existing pavements.

24. Pavement protection. All vehicular traffic shallbe excluded from the pavements for at least 14 days.As a construction expedient, earlier use of pavementis permitted for operations of construction equip-ment only as necessary for paving intermediatelanes between newly paved lanes. Approval for useof the pavements for construction purposes prior to14 days maybe omitted from contract specificationsif unnecessary or undesirable for local conditions.Operation of construction equipment on the edge ofpreviously constructed slabs will be permitted onlywhen concrete is more than 72 hours old and has aflexural strength of at least 400 pounds per square

inch. In all instances, approval for the use of pave-ment will be based on adequate provisions forkeeping pavements clean and protecting pavementsagainst damage.

25. Measurements. When appropriate, contractspecifications may require that concrete bemeasured and paid for on a square-yard basis.Whether concrete is paid for on a square-yard orcubic-yard basis, the unit-price schedule for biddingpurposes will be prepared to show separateestimated quantities for different pavementthicknesses that may be required.

27

TM 5-822-7/AFM 88-6, Chap. 8

APPENDIX A

REFERENCES

Government Publications.

Department of Defense

MIL-STD-621 Test Method for Pavement Subgrade, Subbase,

Departments of the Army and the Air

TM 6-818-2/AFM 88-6, Chap. 4

TM 5-822-6/AFM 88-7, Chap. 1

TM 5-822-9

TM 5-824-3/AFM 88-6, Chap. 3

Environmental Protection Agency

40 CFR, Part 249

and Base-Course Materials

Force

Pavement Design for Seasonal Frost Conditions

Rigid Pavements for Roads, Streets, Walks,and Open-Storage Areas

Repair of Rigid Pavements Using Epoxy-Resin Grouts,Mortars, and Concrete

Rigid Pavements for Airfields Other Than Army

Guideline for Federal Procurement of Cement and ConcreteContaining Fly AshFederal Register, Vol 48, No 20, January 28, 1983

Department of the Army, Corps of EngineersUS Army Engineer Waterways Experiment Station, Structures LaboratoryPO Box 631, Vicksburg, MS 39180-0631

CRD-C 55-86

CRD-C 104-80

CRD-C 119-53

CRD-C 120-55

CRD-C 400-63

Nongovernment Publications.

American Concrete Institute (ACI)

Concrete Mixer Performance

Method of Calculation of the Fineness Modulus of Aggregate

Method of Test for Flat and Elongated Particles and Coarse Samples

Method of Test for Flat and Elongated Particlesin Fine Aggregate

Requirements for Water for Use in Mixing or Curing Concrete

Box 4754, Redford Station, Detroit, MI 48219

ACI 207.5R Roller Compacted Concrete

ACI 211.1-81 Standard Practice for Selecting Proportions for Normal,Heavy-weight, and Mass Concrete

ACI 211.3-75 (Revised 1980) Standard Practice for Selecting Proportions for No-Slump Concrete

ACI 212.lR Admixtures for Concrete

ACI 212.2R Guide for Use of Admixtures in Concrete

ACI 305R-77 Hot Weather Concreting

ACI 306R-78 Cold Weather Concreting

A-1

TM 5-822-7/AFM 88-6, Chap. 8

ACI 544.lR-82

ACI 544.2R-78

ACI 544.3R-84

State-of-the-Art Report on Fiber Reinforced Concrete

Measurement of Properties of Fiber Reinforced Concrete

Guide for Specifying, Mixing, Placing, and Finishing SteelFiber Reinforced Concrete

American Society for Testing and Materials (ASTM)1916 Race Street, Philadelphia,PA 19103

A 775-82 Standard Specification for Epoxy-Coated Reinforcing Steel Bars

C31-69 (R 1980) Making and Curing Concrete Test Specimens in the Field

C 33-82 Standard Specification for Concrete Aggregates

C 78-75 Flexural Strength of Concrete(Using Simple Beam with Third Point Loading)

C 88-76 Test Method for Soundness of Aggregatesby Use of Sodium Sulfate or Magnesium Sulfate

C 94-81 Ready-Mixed Concrete

C 128-79 Specific Gravity and Absorption of Fine Aggregate

C 131-81 Test Method for Resistance to Degradation of Small-Size CoarseAggregate by Abrasion and Impact in the Los Angeles Machine

C 138-81 Unit Weight, Yield, and Air Content (Gravimetric) of Concrete

C 143-78 Slump of Portland Cement Concrete

C 150-82 Standard Specification for Portland Cement

C 173-78 Air Content of Freshly Mixed Concrete by the Volumetric Method

C 192-81 Making and Curing Concrete Test Specimens in the Laboratory

C 227-81 Standard Test Method for Potential Alkali Reactivity of Cement -Aggregate Combination (Mortar Bar Method)

C 260-77 Air-Entraining Admixtures for Concrete

C 295-79 Petrographic Examination of Aggregates for Concrete

C 494-82 Chemical Admixtures for Concrete

C 496-79 Splitting Tensile Strength of Cylindrical Concrete Specimens

C 535-81 Test Method for Resistance to Degradation of Large-Size CoarseAggregate by Abrasion and Impact in the Los Angeles Machine

C 586-69 (R 1981) Potential Alkali Reactivity of Carbonate Rocksfor Concrete Aggregates (Rock Cylinder Method)

C 595-83 Standard Specification for Blended Hydraulic Cements

C 618-83 Fly Ash and Raw or Calcined Natural Pozzolanfor Use as a Mineral Admixture in Portland Cement Concrete

C 666-80 Standard Test Method for Resistance of Concreteto Rapid Freezing and Thawing

A-2

C 682-75 (R 1980)

C 685-83

C 845-80

D 558-82

TM 5-822-7/AFM 88-6, Chap. 8

Standard Recommended Practice for Evaluation ofFrost Resistance of Aggregates in Air-Entrained Concreteby Critical Dilation Procedures

Standard Specification for Concrete Made byVolumetric Batching and Continuous Mixing

Standard Specification for Expansive Hydraulic Cement

Moisture-Density Relations of Soil-Cement Mixtures

D 2922 Density of Soil and Soil Aggregate in Place by Nuclear Methods(Shallow Depth)

American Welding Society2501 NW 7th Street, Miami, FL 33125

AWS D1.4-79 Structural Welding Code–Reinforcing Steel

A-3

TM 5-822-7/AFM 88-6, Chap. 8

APPENDIX B

THIN BONDED RIGID OVERLAYS FOR RIGID PAVEMENTS

B-1. Application. This appendix contains additionalinformation and instructions for preparing contractspecifications for thin bonded overlays for rigidpavements. A thin bonded overlay is generally forcorrection of surface problems, such as scaling orskid resistance, rather than structural upgrading ofthe pavement.

B-2. General. Although the volume of concreterequired for a thin bonded overlay is comparativelysmall, this surface layer is the portion exposed totraffic and weathering and must be of the highestpossible quality. A complete bond must be obtainedbetween the rigid pavement and the overlay. Thethickness of the overlay will be not less than 2 inchesbut not more than 5 inches. The required thickness ofa thin bonded overlay for strengthening roads andstreets will be determined in accordance with TM 5-822-6/AFM 88-7, chapter 1.*

B-3. Correction of defects in existing pavement. Acondition survey should be made and the cause ofcracking of slabs determined in order to develop anappropriate repair prior to overlaying. The existingpavement must be in good structural condition, andany broken or otherwise defective slabs will be repairedor replaced before the overlay is applied. Thedesigner of the overlay should realize that cracks inthe pavement being overlayed will likely reflectthrough the overlay pavement.

B-4. Flexural strength. In general, flexural strengthfor the thin bonded overlay should be about the sameas that obtained for the original pavement construc-tion at the corresponding age.

B-5. Aggregate sizes. The nominal maximum sizeaggregate used will not exceed one-fourth of theoverlay thickness.

B-6. Mixture proportioning. It is desirable for thethin bonded overlay to be as similar as possible in

strength, modulus value, and thermal character-istics. It should also be remembered that thesurface of the concrete is exposed to traffic andweather and should be of high quality. Beyond this,the same guidance given for normal portland cementconcrete applies.

B-7. Preparing the existing pavements. After anynecessary repairs and slab requirements, theexisting pavement surface must be thoroughlycleaned of all deteriorated concrete, oil, grease, anddirt. In order to thoroughly clean the surface, it isrecommended that rotary-type grinders be used toremove at least 1/4 inch of the existing concrete, andin areas where the concrete has deteriorated, thematerial should be removed to sound concrete. Aftergrinding with rotary grinders, the surface should besandblasted to remove debris left from grinding.Before the pavement is placed, the surface of theexisting pavement should be cleaned by broomingand followed with compressed air. In areas whereequipment turns, such as trucks hauling concrete,the existing pavement should be covered with sand orsome other protective cover to prevent rubber fromscrubbing off of tires onto the existing concrete andforming a bond breaker.

B-8. Placement of overlay. Either a neat cementslurry or cement and sand grout is satisfactory forbonding the overlay to the existing surface. Thesemay be applied by pressure spraying or by broomingover the existing surface, but they should be appliedto a dry surface and applied only 6 to 10 feet ahead ofconcrete placing. If the grout or slurry dries beforeconcrete is placed, it should be removed and freshmaterial applied. The concrete should be placed,finished, textured, and cured using normal procedures.Joints in the overlay must coincide with the joints inthe base pavement.

B-9. Payment. Most thin bonded overlays have beenpaid by the square yard of overlay placed.

* References are listed in Appendix A.B-1

TM 5-822-7/AFM 88-6, Chap. 8

APPENDIX C

STEEL-FIBER-REINFORCED CONCRETE

C-1. Introduction. Over the past 10 years fiber-reinforced concrete has been used in numerous trialpavement applications. This composite materialconsists of a concrete matrix containing a randomdispersion of small steel fibers. It exhibits increasedtensile strength, roughness, and span resistancewhen compared to plain or conventionally reinforcedconcrete. Even after an initial tight crack forms,fibers bridge across the crack providing additionalload-carrying capacity until the steel fibers fail orthe bond between the fiber and cement paste fails.Steel-fiber-reinforced concrete designed in accor-dance with TM 5-824-3/AFM 88-6, chapter 3, willbe appreciably thinner than conventional concretepavements. For this reason, steel-fiber-reinforcedpavements offer particular advantages where thethickness of an overlay or pavement must be kept toa minimum to maintain clearances, grades, and

drainage.

C-2. Description. Table C-1 shows typicalcharacteristics of steel-fiber-reinforced concretepavements used at several airfields. Cement contentsare typically much higher than conventional concreteand the aggregate volume is lower. Maximumnominal size aggregate for these mixtures has variedfrom 3/8 to 3/4 inch. Fly ash is often used as a partialsubstitute for Portland cement to improve workabilityand lower the-heat of hydration. Steel fiber contentshave ranged from 80 to 220 lb/yd 3. The addition ofsteel fibers and low water-cement ratios produce astiff mix, and water-reducing admixtures have oftenbeen found to be beneficial. Additional informationcan be found in ACI 544.lR, ACI 544.2R, and ACI544.3R.

c-l

TM 5-822-7/AFM 88-6, Chap. 8

Table C-1. Selected characteristics of fiber-reinforced airfield pavements

II

c

C-2

TM 5-822-7/AFM 88-6, Chap. 8

C-3. Fibers. Fiber-reinforced concrete has beenmade with fibers of many different types of material.However, only steel fibers have been used in pavementapplications. These steel fibers are typically eithercut from wire or sheared from sheets. Typical fibersare 0.01 to 0.02 inch in diameter and 1 to 2 incheslong. The fibers may be straight or the ends maybedeformed. Fibers with deformed ends are said toprovide better anchorage. Ultimate tensile strengthof available fibers varies from 50,000 to 300,000 psi.The maximum fiber aspect ratio (length divided bydiameter) should usually not be over 100 to avoidmixing problems. Also, volume contents of over 2percent are often difficult to mix.

C-4. Fiber clumps. If fiber clumps occur in the mix, itis usually due to fibers being added too fast at somepoint in the mixing operation so that they are alreadyclumped by the time they get into the mixture. Usuallyif the fibers get into the mixture without clumps, noclumps will form. Fibers should not be allowed to pileup anywhere in the operation, and the mixer shoulddisperse the fibers into the mixture as rapidly as theyare added. Other potential causes of fiber clumpingare mixtures with too many fibers, using fibers withtoo large of an aspect ratio, adding fibers too fast to aharsh mix, adding fibers first to the mixer, usingequipment with worn out mixing blades, overmixing,and using a mixture with too much coarse aggregate.A common method of adding fibers to a mix is to addthe fibers through a shaker or hopper onto the fineaggregate on a conveyor belt. Some fibers are alsocollated in bundles of about 30 fibers with a water-soluble glue. These may be added to a mix as the laststep in the mixing process.

C-5. Testing. Fiber-reinforced concrete requiressome modification in testing. The flexural strengthshould include the results of loading past the forma-tion of the initial crack. The conventional slump testis not an effective evaluation of workability forfiber-reinforced concrete. Either Vebe or invertedcone tests are superior to the conventional slumptests. ACI 544.2R should be consulted whenevertests for fiber-reinforced concrete are planned.

C-6. Construction. Before vibration, steel-fiber-reinforced concrete mixtures appear harsh andunworkable, and a common mistake is to add waterin a vain attempt to obtain workability. Conventionalform riding and slipform paving equipment is ade-quate to place and level fiber-reinforced concrete.Use of a jitterbug, rollerbug, or a vibrating screedwill help embed fibers into the concrete, but there isdanger of over-using these techniques and floatingpaste to the surface with very adverse effects ondurability. At least one agency has successfullyspecified a maximum of 18 exposed fibers per squareyard of pavement, and required the contractor todemonstrate the ability to meet this in trial sections.A broom finish is generally used for texturing. Aburlap drag should be avoided to prevent fibers fromcatching in the burlap and tearing the surface.Contraction joints should be saw cut 1/3 to 1/2 thedepth of the slab to assure proper fracturing of thejoint. Recommended joint spacings for fiber-reinforcedconcrete are shown in Table C-2. Other than thesepoints, normal pavement construction and curingtechniques are adequate for steel-fiber-reinforcedconcrete.

C-3

TM 5-822-7/AFM 88-6, Chap. 8

Table C-2. Interim suggested maximum joint spacing for steel-fiber-reinforced concrete

Suggested MaximumSlab Thickness Joint Spacing

in. f t

4-6 12.5

6-9 15.0

9-12

>12 25.0

Sawed contraction joints must be cut deeper to insure opening ofa l l j o i n t s . The saw cut must penetrate one-third to one-half ofthe slab thickness. Otherwise, some of the contraction jointswill not open. Very large separations will then develop atthose joints that do open, causing joint seal and load-transferproblems.

C-4

TM 5-822-7/AFM 88-6, Chap. 8

APPENDIX D

ROLLER-COMPACTED CONCRETE PAVEMENTS; DESIGN AND CONSTRUCTION

D-1. Application. Procedures and criteria describedin this appendix are applicable to the design andconstruction of roller-compacted concrete (RCC)pavement (RCCP).

D-2. General. Roller-compacted concrete pavementemploys a concrete paving technology that involveslaydown and compaction of a zero-slump concretemixture using equipment similar to that used inplacement and compaction of asphaltic concretepavement. By using these construction techniques,the potential exists to save one-third or more of thecost of conventional concrete pavement. Althoughthe concept and technology behind RCCP is relativelynew, RCCP has already proven itself cost-effectivein several projects including log-sorting yards, portfacilities, heavy equipment parking areas, tanktrails, and haul roads.

D-3. Subgrade and base course preparation. Thesubgrade and base course should conform to therequirements outlined in TM 5-822-6/AFM 88-7,chapter 3, or TM 5-824-3/AFM 88-6, chapter 3. Thefreeze-thaw durability of RCCP is not fullyunderstood yet, but is presently being studied at theUS Army Engineer Waterways Experiment Station(WES) and the Cold Regions Research EngineeringLaboratory (CRREL). Good performance has beenobserved in the field; however, marginal performancehas been observed in the laboratory. For this reason,in areas where the pavement or base course might besubjected to seasonal frost action, particular atten-tion should be given to providing a base course thatwill adequately drain any water that infiltratesthrough the pavement or subgrade. The base courseshould provide sufficient support to permit fullconsolidation of the RCCP through its entirethickness upon compaction.

D-4. Selection of materials.a. General. One of the most important factors in

determining the quality and economy of concrete isthe selection of a suitable aggregate source. This isas true for RCC as for conventional concrete. Aggre-gate for RCC should be evaluated for quality andgrading, and should comply with the provisionsoutlined in paragraph 4, with the exceptions noted inthe following discussion.

b. Coarse aggregate. The coarse aggregate mayconsist of crushed or uncrushed gravel, recycledconcrete, crushed stone, or a combination thereof.The quality of coarse aggregate used by the Corps ofEngineers to date in RCCP has generally compliedwith ASTM C 33, although satisfactory RCC maybepossible with coarse aggregate not meeting theserequirements. Local state highway departmentcoarse aggregate grading limits, for example, shouldgenerally be acceptable. A primary considerationshould be that, regardless of the grading limitsimposed, the grading of the aggregate delivered tothe project site be relatively consistent throughoutthe production of RCC. This is an important factor inmaintaining control of the workability of the concretemixture. The nominal maximum aggregate sizenormally should not exceed 3/4 inch, particularly ifpavement surface texture is a consideration. Whenaggregate larger than 3/4 inch is used, segregationand resulting rock pockets are likely to occur.

c. Fine aggregate. The fine aggregate may consistof natural sand, manufactured sand, or a combina-tion of the two, and should be composed of hard,durable particles. The fine aggregate quality shouldgenerally be based on the limits given in ASTM C 33except that consideration should be given torelaxing the maximum 5.0 percent limit of materialfiner than the No. 200 sieve. The amount of materialpassing the No. 200 sieve has been increased inCanada to 8 percent of the total weight of aggregateswith acceptable results. Sands with higher quan-tities of nonplastic silt particles maybe beneficial asmineral filler and may allow some reduction in theamount of cement required. However, mixtures madewith fine aggregates having an excessive amount ofclay may have a high water demand with attendantshrinkage, cracking, and reduced strength. Deter-mination of the specific gravity and absorption ofthese sands with high quantities of fines should bemade according to Note 3 in ASTM C 128.

d. Other aggregates. Recent experience with RCChas shown that aggregate produced for uses otherthan portland cement concrete may also be success-fully used as aggregate for RCC. Material producedfor asphalt paving and base courses have both beenused effectively as RCC aggregate. These materialstypically have a higher percentage of fines passing

D-1

TM 5-822-7/AFM 88-6, Chap. 8

the No. 200 sieve than conventional concrete aggregatesand, as a result, may produce a “tighter” pavementsurface texture. Because these aggregates range insize from 3/4 inch to the No. 200 sieve, control of thegrading may be more difficult due to segregation.Therefore, careful attention must be directed towardstockpile formation and subsequent handling of asingle size group aggregate.

e. Cement. Any available portland cement exceptfor Type III portland cement, any blended hydrauliccement, or combination of portland cement withpozzolan or blended hydraulic cement with pozzolanshould be investigated. If sulfate exposure is aproblem, either Type II, Type V, or a moderatesulfate-resistant blended hydraulic cement shouldbe used. The use of Type III portland cement willalmost never be justified or practical for use in RCCdue to shortened working times with this cement.

f. Admixtures. A proper air-void system must beprovided to prevent frost damage in concrete whichfreezes when critically saturated. Air-entrainingadmixtures have not proven to be effective increating such air-void systems in RCC even whenadded at dosage rates 10 times that of conventionalconcrete. Therefore, to compensate for an inadequateair-void system, RCCP should have a low water-cement ratio, be fully compacted, and have a welldraining base under the pavement. The low water-cement ratio and good compaction provide amaterial with a minimum amount of freezable waterin the capillaries and has low permeability. As longas the RCCP is not critically saturated, it will not bedamaged by freezing and thawing. Durability forresistance to freezing and thawing of RCCP iscurrently being investigated. Neither water-reducingnor retarding admixtures have been shown toimprove the fresh properties of RCC in limitedlaboratory investigations. If the use of theseadmixtures is proposed, such use should be based oninvestigations which show them to produce benefitsgreater than their cost.

D-5. Mixture proportioning.a. General. The basic mixture proportioning

procedures and properties of conventional concreteand RCC are essentially the same; however, conven-tional concrete cannot be reproportioned for use asRCC by any single action such as (1) altering propor-tions of the mortar and concrete aggregates, (2)reducing the water content, (3) changing the water-cement ratio, or (4) increasing the fine aggregatecontent. Differences in mixture proportioning

D-2

procedures and properties are mainly due to therelatively dry consistency of the fresh RCC and theselected use of nonconventionally graded aggre-gates. The primary differences in the properties ofRCC are (1) RCC generally is not air entrained, (2)RCC has a lower water content, (3) RCC has a lowerpaste content, and (4) RCC generally requires ahigher fine aggregate content to limit segregation. Anumber of methods have been used to proportionRCC including those found in ACI 211.3, ACI 207.5R,and ASTM D 558. The first two of these methodsfollow an approach similar to that used in propor-tioning conventional concrete. The third methodtreats the material as cement stabilized soils ratherthan concrete and establishes a relationship betweenmoisture and the density obtained from a particularcompactive effort.

b. ACI 207.5R method. WES has used the methoddescribed in ACI 207.5R, with some modifications,on all RCCP mixtures proportioned by WE S to date(further information on this procedure may beobtained at WESGP/SC, PO Box 631, Vicksburg,MS 39180). The primary consideration when usingthis method is proper selection of the ratio (Pv) of the

air-free volume of paste (Vp) to the air-free volume

of mortar (Vm). This selection is based primarily

upon the grading and particle shape of the fineaggregate. The Pv affects both the compactability ofthe mixture and the resulting surface texture of thepavement. Ratios of 0.36 to 0.41 have been found tobe satisfactory for mixtures having nominal max-imum size aggregate of 3/4 or 1 1/2 inch. The fraction offine aggregate finer than the No. 200 sieve should beincluded in Vp when calculations are made using Pv.

c. Consistency measurements. Since RCC has noslump, an alternative means of measuring mixtureconsistency must be used. Two consistency measure-ment methods have been used to date. One uses theVebe apparatus as described in ACI 211.3, with thefollowing modifications: (1) a 29-pound loose-filledsample is placed in the container and hand leveled,and (2) a total surcharge weight of 27.5 pounds isadded. Consolidation is considered complete whenmortar is visible around the bottom edge of theplastic surcharge disk. The second method followsthe procedures generally described in ACI 207.5R.This method consists of measuring the time requiredto fully consolidate a sample of no-slump concreteby external vibration. Although both methods havebeen used successfully, the latter is more subjectiveand requires the use of a vibrating table having suffi-

TM 5-822-7/AFM 88-6, Chap. 8

cient frequency and amplitude to fully consolidatethe sample. Some commercially available tableshave been found unsuitable without the use of asample surcharge weight. A suggested minimumamplitude and frequency necessary to consolidate anRCC sample without using a surcharge weight is0.0625 inch and 60 Hz, respectively.

d. Sample fabrication. The strength of an RCCmixture is controlled primarily by the water-cementratio and the degree of compaction attained. AllRCCP mixtures placed by the Corps of Engineers todate have had water-cement ratios ranging from0.30 to 0.40. Laboratory strength determinations aremade using fabricated flexural, compressive, andsplitting tensile strength specimens. ConventionalASTM testing methods cannot be followed whenfabricating these specimens due to the dry consistencyof the concrete. The procedure being used is to fillcylinder molds in two layers and beam molds in asingle layer, and consolidate each layer of concreteon a vibrating table. Vibration of each layer iscontinued until paste is discernible over the entiresurface area. Use of a surcharge weight may benecessary to achieve this degree of consolidation. Allspecimens fabricated in the laboratory are to becured according to ASTM C 192.

e. Strength results. Test specimens fabricated andcured in the laboratory generally exhibit higherstrengths than those cored or sawn from an RCCP.This is probably due to the higher unit weightsnormally obtained with the fabricated specimensand the more efficient laboratory moist curing.Laboratory test specimens generally have unitweights which are 98 to 99 percent of the theoretical(air-free) weight of the mixture, while core samplestaken from RCCP normally have unit weights rangingfrom 95 to 98 percent of the theoretical weight.Therefore, fabrication of a companion set of testspecimens having the lowest relative density allowedby the contract specifications should be consideredduring the laboratory mixture proportioning studies.

f. ASTM D 558 method. Studies are currently beingconducted to determine whether a proportioningmethod similar to ASTM D 558 is viable for RCC.Such a method would produce the optimum moisturecontent necessary to obtain maximum density for aparticular set of materials and compaction procedures.Previous tests indicate that the optimum moisturecontent obtained by Method 100 (CE 55) of MIL-STD-621 may produce a mixture too wet to allowefficient operation of a vibratory roller.

D-6. Thickness design.a. General. The thickness design procedure for

RCCP is the same as that used for conventional non-reinforced concrete pavements with no load transferconsidered as outlined in Army TM 5-822-6/AFM88-7, chapter 1, and Army TM 5-824-3/AFM 88-6,chapter 3. Beams sawn from RCCP at Fort Stewart,Fort Hood, and Fort Lewis and tested for flexuralstrength indicate that the actual flexural strength ofthe pavement is 20 to 50 percent higher than thetypical strength assumed in design for thosepavements. This suggests that the thickness designfor compacted RCCP should be modified based uponthe 28-day strength of beams sawn from a testsection constructed, using the same aggregate,cement, and construction procedure as planned forthe entire work. However, until additional perfor-mance records and testing procedures are developedfor RCCP, conventional pavement thickness designwill be used.

b. Lift thickness. The maximum thickness of a liftof RCCP is governed by the ability of the pavers toplace the RCCP in a smooth and continuous fashion.This maximum uncompacted thickness is usually 10to 12 inches. The maximum uncompacted thicknesscan be approximated by multiplying the designthickness by 1.25, thus accounting for the reductionin thickness due to compaction. The minimumthickness of any lift should be 4 inches.

c. Two-lift construction. If the total uncompactedthickness exceeds the capacity of the paver, theRCCP should be placed in two or more lifts, thuscreating a horizontal joint (or horizontal planebetween the layers) in the RCCP. Sufficient bonddevelops at a fresh horizontal joint in RCCP (top liftplaced within 1 hour of bottom lift) to allow the use ofa monolithic thickness design. If the top lift is notplaced within 1 hour of the bottom lift, the thicknessshould be designed as a rigid overlay of a rigid basepavement. The surface of the lower lift should bekept moist and clean until the upper lift is placed,and the upper lift should be placed and compactedwithin 1 hour of compacting the lower lift to insurethat a bond between lifts is formed. In two-liftconstruction, the uncompacted thickness of the firstlift should be two-thirds the total uncompactedheight of the RCCP (or the maximum lift thicknessthe paver can handle, whichever is smaller). Thethinner section in the upper lift aids in creating asmoother final surface, and because of the smallervolume of material, allows the paver placing thesecond lift to move quicker than and follow closer

D-3

I

TM 5-822-7/AFM 88-6, Chap. 8

behind the paver placing the first lift. Multiple liftswill be necessary if the total uncompacted thicknessof the RCCP is greater than twice the maximum liftcapacity of the paver.

D-7. Test section.a. General. A test section should be constructed to

determine the ability of the contractor to mix, haul,place, compact, and cure RCCP. The test sectionshould be constructed at least one month prior to theconstruction of the RCCP at a location near the job-

site. The test section should be large enough toestablish the rolling pattern for the vibratory andfinish rollers, the correlation between laboratory andnuclear gage densities, and the correlation betweenthe number of passes and relative density. The testsection should contain both longitudinal andtransverse cold joints and a fresh joint. A suggestedminimum size is three 12- to 14-foot-wide lanes,each 150 feet long, with one and one-half lanes placedthe first day and the rest placed the next day (see figD-l).

Figure D-1. Typical layout for RCCP test section

- COLD JOINT

- FRESH JOINT

THREE

WIDE LANES

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TM 5-822-7/AFM 88-6, Chap. 8

b. Optimum number of rolling passes. During thetest strip construction, a nuclear gage operated inthe direct transmission mode and standardized witha calibration block should be used to determine theoptimum number of passes with the vibratory rollerto reach maximum density. The density should bemeasured by inserting the nuclear gage probe intothe same hole after each pass of the vibratory roller.The hole should be made with an instrumentspecifically designed for the purpose, and should beformed using the same method throughout the testsection and main construction. This rolling andmeasuring procedure should be continued until thereis less than a 1 percent change in successivereadings. These data may be used in conjunctionwith correlation between the nuclear gage and thelaboratory density to determine the minimumnumber of passes needed to achieve or slightlyexceed the specified density in the RCCP construc-tion. However, a minimum of four vibratory passesshould be used, and this minimum will probablyprevail in most cases.

c. Nuclear gage/laboratory density correlation.After a reasonable estimate is made of the optimumnumber of passes needed for compaction, a correla-tion between the value of in situ RCCP density asmeasured with the nuclear gage and the valueobtained by weighing a sample of the RCCP in airand water should also be determined. This should beaccomplished by measuring the final compacteddensity (after four or more passes with the vibratoryroller) in 10 locations with the nuclear gage, whichhas been standardized with a calibration block. Themeasurement should be made by inserting the probethe full depth of the lane. Then, at 7 days, a pair ofcores should be taken on either side of the remainingnuclear gage holes (within a 1- to 3-foot radius fromthe hole) and the density of the cores measured in thelaboratory by weighing them in air and water. Foreach of the 10 holes, the average of the pair of thelaboratory densities should be compared with theircorresponding nuclear gage density, and a constantrelationship between the nuclear gage and laboratorydensities developed by averaging the algebraicdifferences in these readings. This difference shouldbe combined with future field readings to obtain anadjusted reading which can be compared to thespecified density. In the past a specified density of96 percent of theoretical weight as defined in ASTMC 138 has been achieved. If the adjusted nucleargage density is less than the specified density,additional passes should be made on the fresh RCCP

until the specified density is reached. Two nucleardensity gages should be calibrated (using the sameholes) during the test section construction so that anextra one is available during final construction.

d. Strength tests. Ten cores and beams should betaken from the test section after 28 days to deter-mine a correlation between flexural strength andsplitting tensile strength and/or compressivestrength of the RCCP. This reduces the amount ofsawing necessary to obtain samples during furtherconstruction. Although both the splitting tensileand compressive strength data would be useful forhistorical reference, only one of these tests is neededfor quality control testing of the RCCP construction.After the correlation is determined, the appropriatesplitting tensile and/or compressive strength thatcorrelates to the specified design flexural strengthshould be used in any further quality control testing.

D-8. Batching, mixing, and transporting. RCCPneeds a vigorous mixing action to disperse the relativelysmall amount of water evenly throughout the matrix.This action has been best achieved by using atwin-shaft pugmill mixer commonly used in asphalticconcrete mixing. Batching of the concrete may beaccomplished successfully in either a continuous-mixing or a weigh-batch asphalt plant. The continuous-mixing plant is recommended for batching RCCbecause it is easier to transport to the site, takes lesstime to set up, and has a greater output capacitythan the weigh-batch plant. The weigh-batch plantallows more accurate control over the proportions ofmaterial in each batch, but generally does not haveenough output capacity for larger paving j ohs. Theoutput of the plant should be such that the smooth,continuous operation of the paver(s) is not interrupted,and for all but the smallest jobs (1,000 square yardsor smaller), the capacity of the plant should be noless than 250 tons per hour. The output (or production)of the plant should not be greater than the laydowncapacity of the paver(s) nor greater than the rollingcapacity of the rollers. The plant should be located asclose as possible to the paving site, but in no caseshould the haul time between the batch plant and thepaver(s) exceed 15 minutes. The RCC should be hauledfrom the mixer to the paver(s) in dump trucks. Thesetrucks should be equipped with protective covers toguard against adverse environmental effects on theRCC, such as rain, or extreme cold or heat. The truckshould dump the concrete directly into the paverhopper.

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TM 5-822-7/AFM 88-6, Chap. 8

D-9. Placing. For most pavement applications,RCCP should be placed with an asphalt paver orsimilar equipment. The paver should be equippedwith automatic grade-control devices such as atraveling ski or electronic stringline grade-controldevice. A paver having a vibratory screed or oneequipped with a tamping bar is recommended to providea satisfactory surface texture and some initialcompaction when the RCCP is placed. Necessaryadjustments on the paver to handle the RCC includeenlarging the feeding gates between the feed hopperand screed to accommodate the large volume of stiffmaterial moving through the paver, and adjustingthe spreading screws in front of the screed to insurethat the RCC is spread uniformly across the width ofthe paving lane. Care should be taken to keep thepaver hopper from becoming empty to prevent anygaps or other discontinuities from forming in thepavement. The concrete should be placed andcompacted within 45 minutes after water has beenadded to the batch. When paving adjacent lanes, thenew concrete should be placed within 90 minutes ofplacing the first lane (forming a “fresh” joint), unlessprocedures for cold joint construction are followed(see para D-11). The height of the screed should beset even with the uncompacted height of the adja-scent lane, thus allowing simultaneous compaction ofthe edges of the adjacent lanes into a fresh joint.

When paving rectangular section, paving should bein the short direction in order to minimize the lengthand number of cold longitudinal and transversejoints. Two or more pavers operating in echelon mayreduce the number of cold joints by one half orgreater, and are especially recommended in roadconstruction where the entire width of the road canbe placed at the same time.

D-10. Compaction.a. General. RCCP is best compacted with a

dual-drum (10-ton static weight) vibratory rollermaking four or more passes over the surface toachieve the design density (one back-and-forthmotion is two passes). Table D-1 describes vibratoryrollers that have been used on five recent RCCPprojects. To achieve a higher quality pavement, theprimary compaction should be followed with two ormore passes of a 20-ton pneumatic-tired roller (90psi minimum tire pressure) to close up any surfacevoids or cracks. The use of a dual-drum static (non-vibratory) roller may be required to remove anyroller marks left by the vibratory or pneumatic-tiredroller. A single-drum (l O-ton) vibratory roller hasbeen used successfully to compact RCCP, but mayrequire the use of a pneumatic-tired or dual-drumstatic roller to remove tire marks.

D-6

FrequencyRange

vibrationalmin

128.0 1,1001,500

0.063 10.0

0.0290.016

10.516,000 84.0 190.5 2,200

84.0 134.5 1,5001,700

0.0200.061

8.511,300

84.0 186.8 2,400 0.0160.032

9.015,692

7,275 65 111.9 2,0003,000

0.0750.029

7.0

TM 5-822-7/AFM 88-6, Chap. 8

b. Proper time for rolling. Ideally, the consistencyof the RCCP when placed should be such that it maybe compacted immediately after placement withoutundue displacement of the RCCP. However, no morethan 10 minutes should pass between placing andthe beginning of the rolling procedure. The rollingshould be completed within 45 minutes of the timethat water was added at the mixing plant. A goodindication that the RCCP is ready for compaction isfound by making one or two static passes on theRCCP within 1 foot of the edge of the lane beforevibrating begins and observing the material duringthese two passes to insure that undue displacementdoes not occur. If the RCCP is too wet or too dry forcompaction upon placing, the water content shouldbe adjusted at the plant. Only minor changes inwater content from the design mix should be made;otherwise, a new mix design may be needed. Withpractice, the roller operator should be able to tellwhether the consistency of the RCCP is satisfactoryfor compaction.

c. Rolling pattern. After making the static passes,the vibratory roller should make four vibratorypasses on the RCCP using the following pattern: twopasses on the exterior edge of the first paving lane(the perimeter of the parking area or the edge of aroad) so that the rolling wheel extends over the edgeof the pavement 1 to 2 inches (done to “confine” the

RCCP to help prevent excessive lateral displacementof the lane upon further rolling), followed by twopasses within 12 to 18 inches of the interior edge.This will leave an uncompacted edge to set theheight of the screed for an adjacent lane, and allowsboth lanes of the fresh joint to be compacted simul-taneously. Any remaining uncompacted material inthe center of the lane should be compacted with twopasses of the roller. This pattern should be repeatedonce to make a total of four passes on the lane (ormore if the specified density is not achieved) (see figD-2). If the interior edge will be used to forma coldjoint, it should be rolled exactly as the exterior edgewas rolled, taking care to maintain a level surface atthe joint and not round the edge. When the adjacentlane is placed, two passes should be made about 12 to18 inches from the outer edge of the lane (again, toconfine the concrete) followed by two passes on thefresh joint. The first two passes should extend 1 to 2inches over the outer edge of this adjacent lane if thelane will form an outer edge of the completed pave-ment. Any remaining uncompacted material in thelane should be rolled with two passes of the roller.This pattern should be repeated to make a total offour passes over the RCCP. Additional passes maybe necessary along the fresh joint to insuresmoothness and density across the joint (see figD-3).

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TM 5-822-7/AFM 88-6, Chap. 8

Figure D-2. Compaction of first paving lane

TM 5-822-7/AFM 88-6, Chap. 8

Figure D-3. Compaction of interior paving lanes

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TM 5-822-7/AFM 88-6, Chap. 8

d. Compacting the end of a lane. When the end of alane is reached, the roller should roll off the end of thelane, rounding off the end in the process. This roundedend should be trimmed with a motor grader or withshovels to form a vertical face through the entiredepth of the pavement. An alternative methodinvolves confining the uncompacted end of the lanewith a crosstie or beam anchored to the base course,thereby forming a vertical face at the end of the laneafter compaction.

e. Proper roller operation. During the course of thevibratory compaction, the roller should never stopon the pavement in the vibratory mode. Instead, thevibrator should be turned on only after the roller is inmotion and should be turned off several feet beforethe roller stops moving. The stopping points of suc-cessive rolling passes should be staggered to avoidforming a depression in the RCCP surface. The rollershould be operated at the proper speed, amplitude,and frequency to achieve optimum compaction. Thebest compaction will probably occur at a highamplitude and low frequency (because of the thicklifts) and at a speed not exceeding 2 miles per hour.

f. Finish rolling. The vibratory compaction shouldbe followed immediately with two or more passes ofthe pneumatic-tired roller so that the surface voidsand fissures close to form a tight surface texture.This rolling may be followed by a light dual-drumroller to remove any roller marks on the surface, butthis will probably not be necessary. It is very impor-tant that all exposed surfaces of the RCCP be keptmoist with a light water spray after the rollingprocess until the curing procedure is implemented.

D-11. Cold joints.a. General. A cold joint in RCCP is analogous to a

construction joint in conventional concrete pavement.It is formed between two adjacent lanes of RCCPwhen the first lane has hardened to such an extent

that the uncompacted edge cannot be consolidatedwith the fresher second lane. This happens whenthere is some time delay between placement ofadjacent lanes such as at the end of the day’sconstruction. This hardening may take from one toseveral hours depending on properties of theconcrete and environmental conditions. Nevertheless,the adjacent lane should be placed against the firstlane within90 minutes or be considered a cold joint.

b. Cold joint construction. Before placing freshconcrete against hardened in-place pavement toform a longitudinal cold joint, the edge of the in-placepavement should be trimmed back to sound concreteto form a vertical face along the edge. This verticalface should be dampened before the placement of thefresh lane begins. The height of the screed should beset to an elevation approximately 25 percent higherthan the desired thickness of the compacted concrete.The screed should overlap the edge of the hardenedconcrete lane 2 or 3 inches. The excess fresh concreteshould be pushed back to the edge of the fresh concretelane with rakes or lutes and rounded off so that aminimal amount of fresh material is left on the surfaceof the hardened concrete after compaction. The loosematerial should not be broadcast over the area to becompacted; this may leave a rough surface textureafter rolling. The edge of the fresh lane adjacent tothe hardened concrete should be rolled first, withabout 1 foot of the roller on the fresh concrete, toform a smooth longitudinal joint (see fig D-4).Transverse cold joints are constructed in a similarmanner. After cutting back the rounded-off edgeand wetting the vertical face, the paver is backed intoplace and the screed set to the proper elevation usingshims sitting on top of the hardened concrete. Theexcess material should be pushed back as mentionedbefore, and a static pass made in the transversedirection across the first 1 foot of the freshly placedlane. The joint should be carefully rolled to insure asmooth transition across the joint.

D - n

TM 5-822-7/AFM 88-6, Chap. 8

Figure D-4. Construction of a cold joint

D-12

TM 5-822-7/AFM 88-6, Chap. 8

c. Sawing. The sawing of contraction joints inRCCP has proven to be unnecessary in past projects.Cracks were allowed to form naturally in all of theCanadian-built RCCP, and virtually no distress hasbeen observed at the cracks. These pavements haveendured over 7 years of very heavy loads andnumerous freeze-thaw cycles. Attempts to sawjoints at Fort Hood and Fort Lewis produced a raggededge along the saw cut where pieces of cement pasteand aggregate were kicked out by the saw blade.Until a suitable method is developed for sawingjoints in RCCP, this method should not be used.

d. Load-transfer devices. The stiff consistency ofRCCP does not lend itself to application of load-transfer devices such as dowels or keyed joints,

although dowels were used in cold joint constructionat Fort Stewart. There, the dowels were driven intothe RCCP before final set, and the adjacent freshlane was carefully worked around the dowels byhand. Until an efficient method is developed to insertand align dowels properly in RCCP, the use of dowelsshould be limited.

e. Vertical joints in two-lift construction. In two-lift construction, care should be taken to align thecold transverse and longitudinal joints in the upperand lower lifts to form a uniform, vertical facethrough the depth of the pavement along the joint. Ifthe edge of the upper lift is not even with the edge ofthe lower lift, the lower lift should be cut back evenwith the edge of the upper lift (see fig D-5).

D-12. Curing.a. General. Because of the low water content used

in an RCCP mixture, a combination of moist curingand membrane curing is recommended to preventdrying and scaling of the RCCP surface. The pave-ment surface should be kept continuously moistafter final rolling for at least 24 hours by means of awater spray truck, sprinkler (fog spray) system, orwet burlap or cotton mat covering. If burlap mats

are used, they should be thoroughly wetted, placedon the RCCP so that the entire surface and exposededges are covered, and kept continuously wet. Afterthe initial moist curing period, the RCCP should becured until it is at least 7 days old by one of thefollowing methods: water-spray curing, burlap orcotton mat covering, or membrane-forming curingmaterial. The curing material may be a white-pigmented membrane curing compound or an

D-13

TM 5-822-7/AFM 88-6, Chap. 8

asphalt emulsion. The curing compound or emulsionmust form a continuous void-free membrane andshould be maintained in that condition throughoutthe curing period. An irrigation sprinkler system hasbeen used to cure RCCP in Canada and at FortLewis, but caution should be exercised so that thefines in the surface of the RCCP are not washed awayby excessive spraying.

b. Moist curing. Continuous moist curing of theRCCP for at least 7 days should be considered if frostresistance is a concern. Preliminary results of labora-tory freezing and thawing tests indicate that RCCPwhich has a sufficiently low water-cement ratio andhas been moist cured for an extended period tends tobe more frost-resistant. The improved frostresistance may be due to more complete hydrationresulting in a reduction in fractional volume offreezable water at saturation.

c. Early loading. All vehicular traffic should bekept off the RCCP for at least 14 days. If it isabsolutely necessary, a water-spraying truck andmembrane-spraying truck may be driven onto theRCCP before that age, but this practice should bekept to a minimum.

D-13. Quality control/assurance.a. General. Quality control and quality assurance

consist of testing of materials going into theconcrete; checking the plant calibration regularly;measuring the in-place density of the RCCP using anuclear density gage; checking the smoothness ofthe finished RCCP with a straightedge; taking coresamples from the RCCP for measurement of density,strength, and thickness; and, if desired, fabricatingRCC cylinders and beams.

b. Tests at plant. Moisture contents of the fine andcoarse aggregates should be determined daily asnecessary and appropriate changes made in theamount of mixing water. Washed gradation testsshould normally be performed on the combinedaggregates three times per day: in the morning, atmidday, and in the afternoon. The samples should betaken from the conveyor before the cement or fly ashis added to the combined aggregates. The amount ofmaterials passing the No. 100 sieve should be deter-mined during this analysis. After each gradationtest, a washout test according to procedures inASTM C 685 (para 6.5) may be performed on thecombined dry ingredients on samples taken from theconveyor belt between the cement and fly ash hoppersand the pugmill. By washing the dry ingredientsover the No. 4 and No. 100 sieves and weighing the

material in each size category, the approximateproportions of coarse aggregate, fine aggregate, andcement and fly ash combined may be determined andchecked against predetermined limits.

c. Field density tests. Field density tests should beperformed on the RCCP using a nuclear density gageoperated in the direct transmission mode accordingto ASTM D 2922. At least one field reading shouldbe taken every 100 feet of each paving lane. Thereadings should be taken as closely behind the rollingoperation as possible. The reading should be adjustedusing the correlation determined in the test sectionconstruction and checked against a specified density.Areas that indicate a deficient density should berolled again with the vibratory roller until thespecified density is achieved.

d. Obtaining core samples. The acceptance criteriafor the strength, density, and thickness of RCCPshall be based on appropriate tests conducted oncores taken from the RCCP. Cores should be takenfrom the RCCP when the pavement is 7 days old.One core should be taken at every fifth nuclear gagedensity test site, within a 1- to 3-foot radius of thetest hole. The density and thickness of the coreshould be measured, and the core should be fieldcured under conditions similar to the RCCP curingconditions. The cores should be tested for splittingtensile strength (ASTM C 496) when they are 28days old.

e. Smoothness. The finished surface of the RCCPshould not vary more than 3/8 inch from the testingedge of a 10-foot straightedge. Smoothness shouldbe checked as closely behind the finish roller aspossible, and any excessive variations in the surfaceshall be corrected with the finish roller. Particularattention should be paid to the smoothness acrossfresh and cold joints because this is usually a criticalarea for surface variations. A skilled vibratory rolleroperator is essential in minimizing smoothnessproblems. The final surface texture of the RCCPshould resemble that of an asphalt concrete pave-ment surface.

f. Cylinder and beam fabrication. The fabricationof cylinders and beams during RCCP constructionwould be highly desirable as (1) an aid to the coringoperation in checking the RCCP strength and density,and (2) a means of establishing a data base fordeveloping future quality control criteria. If fabricatedcylinders and beams are to be used as a quality controlaid during construction, a correlation between theirstrength and density and that obtained from coresand sawed beams should be made during test section

D-14

TM 5-822-7/AFM 88-6, Chap. 8

construction. Results of this correlation and theensuring quality control use of fabricated cylindersand beams should be sent to WESGP–EC, PO Box631, Vicksburg, MS 39180, for addition to the abovementioned data base.

g. Method of cylinder and beam fabrication.Cylinders and beams should be fabricated in the fieldby filling cylinder molds in two layers and beammolds in a single layer and consolidating each layerof concrete on a vibrating table. Four beams (onegroup) should be fabricated during each shift ofconstruction, two to be tested at 14 days and two at28 days. The beams should be tested for flexuralstrength according to ASTM C 78. Eight cylinders(one group) should be fabricated for every 300 cubicyards (225 cubic meters) of RCC placed, with onegroup coming from the same batch of RCC used inthe beams. Two cylinders should be tested each at 7,14, 28, and 90 days. The cylinders should be testedfor splitting tensile strength according to ASTM C496.

h. Inspectors. Inspections are vital in the qualitycontrol operations. At least one inspector should bestationed at the mixing plant and at the jobsite toinsure that a quality pavement is being built. At themixing plant, the inspector should check mixingtimes occasionally and spot-check the consistencyand appearance of the mix coming out of the plant.He should also coordinate the aggregate moisture

content tests, the gradation tests, calibration of theplant, and washout tests to see that they are performedproperly and at the right frequency. At the jobsite,the inspector should make sure that the base courseand cold joints are moistened before the RCC is placedagainst them and that the RCC is placed and compactedwithin the proper time limitations. He should checkthe paver operation to insure that proper grade controlis continuously maintained, and to make sure nogaps or discontinuities are left in the pavement beforerolling. The inspector should make sure the rollerbegins compaction at the proper time and that theproper rolling pattern and number of passes is used.He should make sure adequate smoothness acrossjoints is achieved and that the surface texture istight after final rolling. The final compactedthickness of the RCCP should be spot-checked bythe inspector and corrected accordingly, if appro-priate. He should make sure that the curing proceduresare implemented as specified. The inspector shouldalso insure that all exposed surfaces of the RCCP arekept moist at all times and that the curing compound,if used, is applied properly and in a continuousfashion. He should also coordinate the nuclear gagedensity test, the coring procedures, cylinder andbeam fabrication, and the surface smoothness test tosee that they are performed properly and at therequired frequency.

D-15

TM 5-822-7/AFM 88-6, Chap. 8

The proponent agency of this publication is the Office of the Chief of Engineers, United States Army.Users are invited to send comments and suggested improvements on DA Form 2028 (RecommendedChanges to Publication and Blank Forms) direct to HQDA (DAEN-ECE-I), WASH, DC 20314-1000.

By Order of the Secretaries of the Army and the Air Force:

Carl E. VuonoGeneral, United States Army

Official:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Chief of StaffR.L. DilworthBrigadier General, United States ArmyThe Adjutant General

Larry D. WelchGeneral, USAF

Official: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Chief of StaffWilliam O. NationsColonel, USAFDirector of Information Management and Administration

Distribution:Army:

Air Force:

To be distributed in accordance with DA Form 12-34B, Requirements for Provi-sions and Designs—Roads, Streets, and Walks.

F