U.F. Project No. 4910450429812 State Project No. 99700-7520-010

W.P.I. No. 0510546 Contract No. Co3352

EVALUATION OF GROUND TIRE

RUBBER IN ASPHALT CONCRETE

Submitted To: Florida Department of Transportation

January 1992

Department of Civil Engineering College of Engineering UNIVERSITY OF FLORIDA Gainesville

Engineering & Industrial Experiment Station

Byron E. Ruth

Final Report

U.F. Project No.: FOOT Project No.:

W. P.I. No.: Contract No.:

4910450429812 99700-7520-010 0510546 C-3352

EVALUATION OF GROUND TIRE RUBBER IN ASPHALT CONCRETE

Submitted to

Florida Department of Transportation

Dr. Byron E. Ruth

Department of Civil Engineering College of Engineering University of Florida Gainesville, Florida

January 1992

Engineering & Industrial Experiment Station

ACKNOWLEDGEMENTS

This investigation was successfully completed primarily because of the

efforts and dedication of Florida Department of Transportation (FDOT) personnel.

Mr. Lawrence L. Smith, State Materials Engineer, provided overall direction in

the research program involving waste by-product utilization, of which the ground

tire rubber (GTR) project was one of the areas of investigation. Messrs. Gale

C. Page and Kenneth H. Murphy were co-principal investigators responsible for

planning and data acquisition for this project. Mr. James A. Musselman and Mr.

Randy C. West provided technical assistance and coordination of the testing pro­

gram. Mr. Michael R. Flanagan, District Director of Operations, and other 2nd

District personnel cooperated with the Materials Office in planning and imple­

menting the construction of three demonstration projects. The author wishes to

express his sincere appreciation for the valuable assistance and cooperation pro­

vided by these individuals.

TABLE OF CONTENTS

ACKNOWLEDGEMENTS

LIST OF TABLES

LIST OF FIGURES

I NTRODUCTI ON

BACKGROUND: TECHNICAL CONSIDERATIONS

PAVEMENT PERFORMANCE ON DEMONSTRATION PROJECTS

BLENDING OF GTR WITH ASPHALT ....

TYPE AND AMOUNT OF GTR IN FRICTION COURSE MIXTURES

ASPHALT-RUBBER MEMBRANE INTERLAYER ..

ENVIRONMENTAL ASPECTS OF ASPHALT-RUBBER

SPECIFICATIONS FOR ASPHALT-RUBBER HIGHWAY CONSTRUCTION APPLICATIONS ................ .

PROJECTIONS FOR THE UTILIZATION OF GROUND TIRE RUBBER

REFERENCES

APPENDIX A:

APPENDIX B:

APPENDIX C:

APPENDIX D:

APPENDIX E:

APPENDIX F:

Section 919 - Ground Tire Rubber for Use in Rubber Modified Asphalt Binder .......... .

Section 336 - Rubber Modified Asphalt Binder ...

Section 337 - Asphaltic Concrete Friction Courses

Section 918 - Asphaltic Concrete - Latex Additive

Section 341 - Rubber Modified Asphalt Membrane Interlayer

FM5-548-Viscosity of Rubber Modified Asphalt by Rotational (Dip-N-Read) Viscometer ............... .

i i

iii

iv

1

1

7

18

23

25

26

27

29

32

33

36

40

49

52

. 56

LIST OF TABLES

1 Summary of Asphalt-Rubber Friction Course Demonstration Projects . . . . . . . . . . . . . . . 4

2 Skid Performance History for SR 120 (23rd Avenue, Gaines-ville, Florida) ....... . 8

3 Skid Performance History for SR 16 (Starke, Florida) 8

4 Skid Performance History for Interstate 95 (St. Johns County, Florida) ............... ..... .. . 9

5 Comparison of Pavement Performance Data for SR 120 (N. E. 23rd Avenue) ......... . . . . . 14

6 Comparison of Pavement Performance Data for SR 16 (Westbound Traffi c Lane, Starke, Flori da, August 26, 1991) . . . . . . . 15

7 Comparison of Pavement Performance Data for 1-95 (St. Johns County, Florida, September 16, 1991) ........ 15

8 Comparison of Densities for SR 120 (N.E. 23rd Avenue) 16

9 Terminal Blending Project, Coastal Fuels, Pensacola July 25-29, 1991 .......................... 20

iii

LI ST OF FIGURES

Figure

1 Pavement Friction Trends for SR-120

2 Pavement Friction Trends for SR-16

3 Pavement Friction Trend for Interstate 95 (Rib Tires)

4 Tensile Strength of GTM and Marshall Specimens

5 Asphalt-Rubber Storage Characteristics

6 Sample Temperature Effect on the Viscosity of Asphalt-Rubber

11

12

13

17

21

with 12%, 80 mesh, GTR . . 22

7 FOOT Viscosity Test Results . . . . . . . . . . . . . . . . . 24

iv

INTRODUCTION

In 1988, the Florida Legislature passed Senate Bill 1192 which set forth

in Section 336.044 of the Florida Statutes a directive to the Florida Department

of Transportation (FOOT) to expand, where feasible, its use of recovered (waste)

materials for highway construction. Specifically, the bill directed that an in­

vestigation be conducted to determine how ground tire rubber (GTR) from waste

tires could be used in qual ity asphalt concrete mixtures for highway construction

by undertaking demonstration projects as part of the currently scheduled con­

struction program. Furthermore, it stipulated that within one year after the

conclusion of the demonstration projects the FOOT shall report to the Governor

and the Legislature on the maximum percentage of ground tire rubber that can be

effectively utilized in road construction projects. Concurrent with the submis­

sion of the report the FOOT shall review and modify its standard road and bridge

construction specification to allow and encourage the use of ground tire rubber

consistent with the findings of the demonstration projects.

These Legislative mandates have been complied with by conducting various

laboratory and field investigations and by documentation of the results in pub­

lished technical reports. Although the major work associated with this effort

was performed by personnel in the FOOT Materials Office, the Department of Civil

Engineering, University of Florida, provided technical assistance and prepared

the technical reports.

BACKGROUND: TECHNICAL CONSIDERATIONS

The use of asphalt-rubber in highway pavement applications is not new.

Asphalt-rubber has been used in Arizona and the southwest region of the USA for

many years. It has been used as a binder for asphalt concrete mixtures and as

a stress relief interlayer which has a good reputation for its effectiveness in

reducing or eliminating reflective cracking. During the late 70's, nearly 10

1

years before passage of Senate Bill 1192, the FOOT investigated asphalt-rubber

for use as a stress absorbing interlayer and binders in seal coat construction.

A demonstration project constructed on SR 60, Hillsborough County, was used to

evaluate the performance of asphalt-rubber in these applications. As a result

of this demonstration project, documented in a 1980 FOOT report for the U.S. De­

partment of Transportation (1), the FOOT has permitted the use of GTR in selected

surface treatment and interlayer construction. Also, the FOOT currently permits

the use of GTR in certain jOint sealers and in railroad crossing pads.

Upon passage of Senate Bi 11 1192 by the 1988 Legi sl ature, FOOT personnel

in cooperation with University of Florida researchers establ ished and implemented

a detailed plan to address this legislative mandate. The relatively short time

period allocated for this investigation made it necessary to schedule concurrent

activities. One primary activi~y was to document pertinent information from

technical literatUre. The National Center for Asphalt Technology (NCAT) at

Auburn University was selected to conduct this investigation because of their

knowledge and experience with asphalt-rubber, paving mixtures, and construction

processes. Their report, dated August 1989, provided a comprehensive documenta­

tion of material properties, benefits, limitations and recommendations for utili­

zation of ground tire rubber and asphalt rubber binders (2). It was noted that

basic research into the interaction of GTR with asphalt was lacking. This state­

of-the-art overview of asphalt rubber in an asphalt concrete application con­

firmed and validated the direction for the FOOT in the development of the demon­

stration projects which were subsequently constructed. This confirmation was of

major importance to the FOOT to assure that there was no undesirable impact from

asphalt-rubber on the asphalt concrete pavement recycling program.

The pavement recycling program in the State of Florida is probably the most

effective and operational system that can be found throughout the world. This

statement is based upon the viability of the recycl ing program. At present about

2

85 percent of all asphalt concrete structural mixtures (hot-mix) contain on the

average about 35 percent reclaimed asphalt pavement (RAP). The quality of these

recycled mixtures are equivalent to or better than conventional mixtures and

their cost is generally 25 percent less per ton of mix than mixtures with virgin

aggregates. This cost saving does not include savings derived from not having

to raise shoulders or maintain vertical clearances as is necessary on overlay

construction. These structural mixtures are not suited for the addition of GTR

because it would interfere with the rejuvenation of the old binder (transfer of

malthenes) that occur during the recycling process. Consequently, the greatest

potential for GTR appeared to be in its use in asphalt-rubber binders for fric­

tion course mixtures. This was considered a very promising application in open­

graded friction course mixtures because it should provide increased binder reten­

tion without drainage from the hot-mix in haul trucks. This increase in binder

content and resiliency may increase aggregate retention, reduce raveling, and in­

crease longevity (durability). The addition of GTR increases asphalt binder vis­

cosity which allows for greater film thickness retention and improved resistance

to age hardening due to anti-oxidants in the GTR. In the dense graded friction

course mixtures, the GTR should improve the resilience of the binder (greater

elastic response) thereby reducing longitudinal and transverse shoving at major

intersections.

In 1989 and through 1990, three demonstration projects were constructed to

evaluate the use of GTR in asphalt concrete friction course mixtures. A summary

of key information for these projects is presented in Table 1. Each project re­

quired a substantial preliminary effort to assure the best possible operational

conditions for production, construction, and testing for materials evaluation.

This involved development of work plans, special provisions, mix designs, and

considerable interaction with the prime asphalt contractor and the subcontractor

providing the blending of GTR with the asphalt cement. During construction,

3

Table 1

SUMMARY OF ASPHALT-RUBBER FRICTION COURSE DEMONSTRATION PROJECTS

1st Demonstration 2nd Demonstration Project Project

Date March 1989 June 1989 Constructed:

Location: N.E. 23rd Avenue State Road 16 Gainesville, FL Starke, FL

Dense-Graded Open-Graded Type of Mix: Friction Course Friction Course

(FC-4) (FC-2)

Ground Tire (1) 80 mesh/3% (1) 80 mesh/5% Rubber Test (2) 80 mesh/5% (2 ) 80 mesh/l0% Sections (3) 40 mesh/l0%lbl (3) 80 mesh/15% S i ze/% GTRlal (4) control/O% ( 4) 24 mesh/17%

(5) control/O% (6) 80 mesh/l0%ICI

Total Binder (1) 7.1% (1) 8.0% Content (2) 7.3% (2) 8.4%

(3) 8.2%lbl (3) 11. 4% (4) 7.0% (4) 10.3%

(5) 6.3% (6) 6.9%

Length of Test (1) 3520 ( 1 ) 2100 Sect ion - ft. (2) 3656 (2) 2532

(3 ) 2460 (3 ) 1818 ( 4 ) 2880 (5 ) 1761 (6 ) 263

Comments: 5% GTR of 80 mesh 10 to 15% GTR ap-GTR Produced the pears satisfac-best results dur- tory. Either 80 or ing construction. 24 mesh GTR could

probably be used.

Note: Numbers in ( ) designate section numbers. lal By weight of total binder Ibl Also included 5.0% extender oil I~ Not preblended - mixed in pugmill

4

3rd Demonstration Project

September 1990

Interstate 95 St. Johns County

Open-Graded Friction Course

(FC-2)

( 1 ) 80 mesh/l0% (2) 80 mesh/l0% (3 ) 80 mesh/l0% ( 4 ) 80 mesh/l0%

( 1 ) 7.17% (2) 7.17% (3) 7.17% (4) 7.17%

( 1 ) 5260 (2 ) 5655 (3 ) 5513 ( 4 ) 5937

Blending temp. too low (275F). In-creased blending time to 45 min. Both aspha It-rubber and conven-tional mix were placed with equal ease.

extra sampling and specialized tests were performed in addition to the standard

quality control and quality assurance tests. This required a concentrated effort

to furnish a sufficient number of qualified personnel to conduct these tests and

to observe construction procedures for assessment of any problems or deficien­

cies.

The first demonstration project (3) was constructed in Gainesville during

March 1989 using a dense-graded friction course (FC-4) containing 3, 5, and 10

percent GTR (by weight of total binder). Dense-graded friction course mixtures

are generally more susceptible to changes in binder content and particle size of

GTR than open-graded mixtures. Tests including the Corps of Engineers Gyratory

Testing Machine (GTM) were conducted on the hot-mix samples with different levels

of GTR which indicated that the mix from Test Section 2 with 5.0 percent GTR

appeared to be the best mix. Test Section 3 with 10.0 percent GTR produced lower

laboratory and field densities and lower gyratory shear than the 5 percent GTR

modified binder. Although all of the asphalt-rubber mixtures exhibited some de­

gree of sticking to the paver's screed, it was only considered excessive during

paving of Test Section 3 which had 10 percent GTR. Otherwise, no major problems

were encountered during construction of these asphalt-rubber friction courses.

The second demonstration project (4) was constructed on SR 16 near Starke

in June 1989 using 5 to 17 percent GTR (by weight of total binder) in an open­

graded friction course (FC-2). Construction was accomplished without any signif­

icant difficulty or observable problems. Test Sections 3 and 4 with 15 and 17

percent GTR, respectively, had high total binder contents which could exhibit

long term performance and hydroplaning problems although there is no evidence of

a problem after 30 months in service. The results obtained from construction of

this demonstration project indicated that 10 to 15 percent GTR can effectively

be used in open-graded friction course mixtures, but the total binder content

should probably be less than used in the mixtures on this project.

5

The University of Florida provided technical assistance and documentation

of these projects (3,4). A report prepared by the FOOT Materials Office (5) also

provides a general overview and summary of FOOT involvement through September

1989. Of primary importance is the preliminary laboratory investigations con­

ducted by the FOOT to establish asphalt-rubber blends and mix designs for the

first two demonstration projects. Other special studies were conducted to evalu­

ate asphalt-rubber blending requirements and the effectiveness of extraction

testing (6).

The third and last demonstration project was constructed on Interstate 95

during September 1990 using 10% GTR (by weight of asphalt cement). The purpose

of this project was to determine whether or not asphalt-rubber could be blended

and incorporated into an open-graded friction course mixture using a prototype

production blending unit on a conventional construction project without encoun­

tering any problems which would contribute to construction defects or delays.

The information collected on this demonstration project is documented in a tech­

nical report from the University of Florida (7). This demonstration project was

constructed without any major technical problems. However, the blending time re­

quired to provide adequate reaction of GTR with the asphalt cement had to be in­

creased to 45 minutes with this prototype blending unit because of the lower than

anticipated temperature (275'F instead of 310'F) of the asphalt cement. This in­

dicated the need to either increase the blending unit capacity or provide addi­

tional heating for the unit to assure adequate blending to maintain hot-mix pro­

duction rate at the desired 100 tons/hour. This project was established using

the conventional bid process which resulted in a 31 percent increase in cost for

these short sections of fri ct i on course wi th GTR over convent i ona 1 fri ct ion

course construction on the same project.

The constructability and short term performance of these asphalt-rubber

test pavements indicate that it is feasible to use GTR for friction course con-

6

struction without any major change in construction operations. Although the long

term performance of these pavements cannot be evaluated until some time in the

future, there is sufficient test data and corroborating information that suggest

asphalt-rubber fri ct i on courses, parti cul arly open-graded, have improved durabi 1-

ity over conventional friction course mixtures. This improvement is related to

I) reduced age hardening because of anti-oxidants in the rubber and increased

film thickness, and 2) improved retention of aggregate because of increased film

thicknesses and greater resiliency. Greater binder contents and the retention

of thicker binder films on the aggregate are possible because of the increase in

viscosity produced by the addition of GTR.

As a result of the information obtained from the literature, laboratory,

and various demonstration projects, an executive summary report was prepared to

advise the Florida Legislature of the findings derived from the investigation

(8). Developmental specifications were included in the report to serve as a

guide for any additional construction projects until further information could

be collected for use in making improvements to these specifications. Subse­

quently, modifications were made and incorporated into the current version of the

specifications which is presented in a later segment of this report.

PAVEMENT PERFORMANCE ON DEMONSTRATION PROJECTS

Skid resistance and pavement performance data were collected on each demon­

stration project at the time of construction and at various time intervals there­

after. Tables 2, 3, and 4 present the friction data for the SR 120, SR 16, and

Interstate 95 projects. As to be expected, the friction number for SR 120 with

the dense graded friction course mixtures decreased slightly during the first 12

months but remained fairly constant afterwards. Conversely, the open-graded

friction course mixtures on SR 16 in general exhibited a slight increase in fric­

tion number after several months of traffic. At IS months the average friction

numbers for blank and rib tires were 31.7 and 33.5, respectively. This is typi­

cal of open-graded friction courses since both tire types often yield about the

7

Date Time Months

03/30/89 0

12/12/89 9

03/26/90 12

04/10/90 13

01/04/91 22

01/06/92 34 Rl: 3 percent GTR R2: 5 percent GTR

Date Time Months

06/15/89 0

06/22/89 0.5

08/02/89 2

08/30/89 3

01/12/90 6

06/28/90 12

07/06/90 13

01/04/91 18

01/06/92 30

(B) Blank Tires (R) Rib Tires

Table 2

SKID PERFORMANCE HISTORY FOR SR 120 (23rd Avenue, Gainesville, Florida)

Fn (40)

Rl R2

40 40

37 37

35 30 -- --- - - -

22 20

Friction Number Blank

R3 R4 Rl

39 40 46 37 36 46 34 31 36 - - -- 38 -- -- 35

27 31 38 R3: 10 percent GTR R4: 0 percent GTR

Table 3

SKID PERFORMANCE HISTORY FOR SR 16 (Starke, Florida)

Friction Number Sec. 1 Sec. 2 Sec. 3 Sec. 4

B R B R B R B R

31 31 26 25 26 24 28 27

30 31 27 26 27 27 29 28 30 34 28 32 28 31 30 33

31 31 29 30 30 30 33 33

30 32 30 31 30 31 31 33

33 35 32 35 33 33 34 37

30 35 29 33 30 33 31 34

31 33 33 33 31 32 30 33

27 33 26 32 26 31 27 33

Fn (40) Rib

R2 R3 R4

45 43 47 43 44 44

34 36 37

35 37 36

36 40 36

32 35 33

Sec. 5 Sec. 6

B R B R

27 26 26 25

28 27 29 28

31 36 34 35

32 32 32 31

33 34 33 35

34 38 32 37

33 36 31 34

33 35 32 35

30 37 27 35

Percent GTR: 5% Sec.l, 10% Sec.2, 15% Sec.3, 17% Sec.4, 0% Sec.5-Control, 10% Sec.6

8

Table 4

SKID PERFORMANCE HISTORY FOR INTERSTATE 95 (St. Johns County, Florida)

Date Time Percent Months Rubber

10/02/90 0 101')

01/07/91 3 101,)

10/02/90 0 Olb)

01/07/91 3 Olb)

I,) 7.17 Percent Binder Content Ibl Control

Friction Number

NB-TL NB-PL SB-TL

43 36 41

36 38 36

44 40 42

36 40 36

9

SB-PL Mean

37 39.3

37 36.8

37 40.8

37 37.3

same results. The Interstate 95 data in Table 4 indicates that both asphalt­

rubber and control pavement sections provided similar friction numbers. Figures

1 through 3 illustrate the trends in friction number.

Pavement performance data for SR 120 are given in Table 5. This data com­

bined with visual inspections indicated that all asphalt-rubber and control test

sections are performing very well. Similarly the open-graded friction course

mixtures on SR 16 and Interstate 95 seem to be performing well although the ride

on SR 16 (see Table 6) is not nearly as good as on the other demonstration proj­

ects, particularly Interstate 95 (Table 7) which from a visual standpoint looks

very good. The 1-95 friction course has a very uniform surface texture and there

does not appear to be any difference between asphalt-rubber and control sections.

A variety of tests other than skid and performance surveys were conducted

on the dense graded friction course test sections (SR 120). Table 8 presents tbe

Marshall and Gyratory Testing Machine (GTM) compacted densities for plant mix

which can be compared to field core densities. The GTM compacted densities were

slightly lower (0 to 2 pcf) than Marshall compacted densities except for Test

Section R3 which was 3.7 pcf lower. In all cases the GTM densities provided the

best estimate of the densities achieved in the different pavement sections.

Other than Section R3, there was no indication of an increase in the densities

of test sections over the 24 month period. However, Test Section R3 appears to

have densified almost 5 pcf after 2 years of traffic. It seems probable that the

higher binder content combined with the 10 percent GTR and mixture fines inter­

acted to produce greater initial resistance to densification.

The results of indirect tension tests using 50-blow Marshall, GTM, and

field compacted samples is illustrated in Figure 4. It is obvious that the ten­

sile strength of Section R3 was less than the other sections regardless of den­

sity. This does not mean the mixture was substandard but that the extender oil

reduced the binder viscosity and indirect tensile strength. This effect is par-

10

SKID DATA: SR 120 DENSE GRADED FRICTION COURSE DEMO PROJ.

Fn(40) RIB 50

........ ., "

r- "'" . ..... ,

45

40

35

30

25

20

15

10

~ ¥ . :--!" .....

5

o o

- SECTION 1 (3%)

-+- SECTION 2 (5%)

-+- SECTION 3 (10%)

-6- SECTION 4 (0%)

6 W 18 24 30

MONTHS AFTER CONSTRUCTION

SKID DATA: SR 120 DENSE GRADED FRICTION COURSE DEMO PROJ.

Fn(40) BLANK

..,. ...

....

...

36

50,-------------------------------------------,

45

40~~~~ 35

30

25

20

15

10

- SECTION 1 (3%)

-+- SECTION 2 (5%)

-+- SECTION 3 (10%)

-9- SECTION 4 (0%) 5

OL===~====~~--~--~----~--~ o 6 12 18 24 30 36

MONTHS AFTER CONSTRUCTION

Figure 1 Pavement Friction Trends for SR-120

11

SKID DATA: SR 16 OPEN-GRADED FRICTION COURSE DEMO PROJECT

Fn(40) RIB 40,-------------------------------------------,

20 - SECTION 1 (5%)

-+- SECTION 2 (10%)

-+- SECTION 3 (15%) 15

10 -B- SECTION 4 (17%)

~ SECTION 5 (0%) 5 -€-- SECTION 6 (10%)

o~--~----~--~--==~======~ o 6 12 18 24 30

MONTHS AFTER CONSTRUCTION

SKID DATA: SR 16 OPEN-GRADED FRICTION COURSE DEMO PROJECT

Fn(40) BLANK

36

40,---------------------------------------------,

35 -- -- -~-

30

25

20

15

10

5

o~--~----~----~~~====~==~ o

MONTHS AFTER CONSTRUCTION

Figure 2 Pavement Friction Trends for SR-16

12

SKID DATA: 1-95 OPEN-GRADED FRICTION COURSE, DEMO PROJECT

50

I- NB· T,=--~

40 I- Range in - SB. Pl SBT!.: ) Control 0 o:r I=" NB- PL Sections -c: u-

30 l-

I-

200

, , , • 1 2 3 4 MONTHS AFTER CONSTRUCTION

Figure 3 Pavement Friction Trends for Interstate 95 (Rib Tires)

13

Table 5

COMPARISON OF PAVEMENT PERFORMANCE DATA FOR SR 120 (N.E. 23rd Avenue)

Test Rutting Cracking & Ride Section Date In. Patching IRI/PSI Sq. Ft.

R1 (EBL) 04/04/89 0.00 0.00 NA/4.64 10/13/89 0.00 0.00 NA/4.62

(3% GTR) 08/26/91 0.03 0.03 62/

R2 (WBL) 04/04/89 0.00 0.00 NA/4.64 10/13/89 0.00 0.00 NA/4.63

(5% GTR) 08/26/91 0.04 0.00 68/

R3 (WBL) 04/04/89 0.00 0.00 NA/4.63 10/l3/89 0.00 0.00 NA/4.49

(10% GTR) 08/26/91 0.02 0.08 76/

R4 (EBL) 04/04/89 0.00 0.00 NA/4.58 10/13/89 0.00 0.00 NA/4.52

(0% GTR) 08/26/91 0.03 0.00 62/

14

Section

1

2

3

4

5

6101

Tab 1 e 6

COMPARISON OF PAVEMENT PERFORMANCE DATA FOR SR 16 (Westbound Traffic Lane, Starke, Florida, August 26, 1991)

Percent Binder Rutting Cracki ng & Ride Rubber Content In. Patching IRI/PSI % Sq. Ft.

5 7.98 0.04 0.00 100/

10 8.39 0.08 0.00 107/

15 11. 45 0.08 0.00 110/

17 10.28 0.09 0.00 118/

0 6.3 0.09 0.00 98/

10 6.88 0.06 0.00 95/

1,1 Ground tire rubber not prebl ended but added dry to pugmi 11 .

Section 1

Control

Table 7

COMPARISON OF PAVEMENT PERFORMANCE DATA FOR 1-95 (St. Johns County, Flori da, September 16, 1991)

Rutting Cracking & In. Patching

Sq. Ft.

SB-TL 0.07 0.00

NB-TL 0.07 0.00

SB-TL 0.05 0.00

NB-TL 0.08 0.00

15

Ride IRI/PSI

51/

49/

52/

58/

Test Percent Section Rubber

Rl 3

R2 5

R3 10

R4(b) 0

Table 8

COMPARISON OF DENSITIES FOR SR 120 (N. E. 23rd Avenue)

Mean Density - pcf

Field Cores

Binder Marshall GTM As Con-Content 50-Blow ( a) structed 6 mo. %

7.09 124.5 122.8 121. 5 122.8

7.29 125.7 124.9 123.4 124.2

8.12 123.8 120. I 119.8 123.7

6.80 126.8 126.5 125.2 124.2

24 mo.

122.4(c)

123.4(c)

124.8

124.8(c)

(a) Gyratory Testing Machine: 3 degree initial angle of gyration, 100 psi ram pressure, 10 psi initial air roller pressure, 18 revolutions

(b) Control Section

(c) Indicates no change in density over 24 months

16

240~----------------------------------------~

J: 200 I-(.5 :z ~ HiD

tii ~ 120 en :z w I- 80

lJ w IX: 2i 40 :z

Legend o Marshall o 1.0' Cores, nF IIiIIIGTM "'1.0' Cores, 75F, 2 years

R310C(50F)

III

R1 '24C (75F\ '" -

R2 --<> 0-

0 0 R1

R4 R3

R4 R2 '2 :!~~S J': -

R2 R4

'V ",R3 R1

25C (nF) R3

120 122 124 126 128 oL---~--~----~--~----~--~----~---L--~

DENSITY - PCF

Figure 4 Tensile Strength of GTM, Marshall and Core Specimens

17

ticularly noticeable at the 10C (50F) test temperature. However, the field den­

sities for Section R3 increased about 5 pcf. It 'is undesirable to have excessive

densification which may result in consolidation rutting or even excess plastic

deformation (transverse shoving) if the air void content becomes excessively low.

BLENDING OF GTR WITH ASPHALT

It is recognized that asphalt-rubber binders must be properly formulated

and blended to achieve a stable and relatively homogeneous material. Blending

constitutes the introduction of GTR into hot asphalt cement which is mechanically

mixed for a sufficient time to provide dispersion and to allow for the GTR rubber

particles to reach equilibrium in the absorption of asphalt light fractions. The

blending time is reduced when using finer GTR, softer asphalt cements, and higher

blending temperature. Although the blending time is reduced at higher tempera­

tures, excessive temperature and holding at elevated temperatures for long

periods of time will degrade the quality of the asphalt-rubber binder.

Blending time requirements are generally based on viscosity measurements

taken at different time intervals to determine when the blend achieves a fairly

stable consistency. Rotational viscometers such as the Haake and Brookfield are

often used for laboratory and field measurement of asphalt-rubber viscosities.

Rotational viscometer data were obtained on all of the demonstration projects to

determine blending time requirements. Exploratory laboratory studies were con­

ducted by the FOOT to determine blending time requirements for several different

sizes of GTR. It was found that GTR finer than the No. 30 sieve needed to be

blended at 325F for only 10 to 15 minutes to achieve good dispersion and uniform

viscosity. However, the FOOT wanted to verify that these results were indicative

of full scale processing of asphalt-rubber blending.

The Interstate 95 demonstration project provided information on the blend­

ing of GTR and asphalt cement at the contractor's asphalt plant site. The con­

cept that terminal blending was feasible from an operational standpoint needed

18

to be verified. The FOOT initiated a study to evaluate blending of asphalt-rubber

binders at an asphalt producer's terminal in Pensacola, Florida. If terminal

blending proved to be acceptable, then time and cost savings should be achieved

by allowing the material to be blended at five or six terminal locations and

transported to the construction sites rather than having blending equipment at

each of the approximately 140 asphalt hot-mix plant sites throughout the state.

Also, it was believed that product uniformity and quality would be more easily

achieved with terminal blending facilities.

The Rouse blending process (7) was used at a Pensacola terminal to blend

12 percent GTR (80 mesh) by weight of AC-30 asphalt cement. Temperatures in the

range of 325F were used for blending. Asphalt-rubber binder storage temperatures

were monitored and samples of the material taken for testing at various time in­

tervals over a period of four days. These test results and visual observations

were used to evaluate the storage stability of the asphalt-rubber binder material.

Table 9 presents the data collected from the terminal blending study. Vis­

cosity measurements were obtained using the DIP-N-READ rotational viscometer in

one-quart samples of the asphalt-rubber blend. Figure 5 illustrates the viscos­

ity trend over the 96 hour testing period. Tank temperatures during the study

were 325F at the time of blending with subsequent variation between 320F to 285F.

Sample temperatures ranged between 270F to 300F which affected the viscosity

readings as illustrated in Figure 6. There was no indication of binder softening

with time due to degradation of the GTR. Other investigators had previously de­

termi ned that storage of asphalt-rubber bi nders at temperatures of 350F and

higher resulted in a breakdown of the GTR which produced a reduction in viscosity

(softening). Conversely, the data (softening point and resilience tests) from

the terminal blending studies indicated that there was a slight amount of hard­

ening at the longer storage time.

19

TIME OIP-N-REAO lal

(HRS) VISCOSITY (POISES)

0.25 3.9

0.50 3.9

0.75 4.2 2

1.0 4.3

2.0 4.8

4.0 6.1

24 8.3

48 6.3

72 6.9

96 7.6

Table 9

TERMINAL BLENDING PROJECT Coastal Fuel s, Pensacol a

July 25-29, 1991

SAMPLE TANK TEMP TEMP ( 'F) ( 'F)

300 325

295 320

290 325

295 318

285 321

282 307

270 285

285 312

285 309

282 306

Lab Tested Samples

SOFTENING RES I L! ENCE 1bl

POINT (%) ( 'F)

137 8.67

137 8.83

137 9.33

136 9.67

139 10.00

137 10.00

139 14.13

140 18.66

143 20.17

145 24.50

lal

Ibl

Rotational viscometer tests conducted in one quart sample cans containing AC-30 blended with 12% (by wt. of AC) of Ground Tire Rubber (80 mesh). ASTM 03407-78

20

4

2

ASPHALT RUBBER STORAGE CHARACTERISTICS Pensacola. Florida

Temperature (Degrees F) r-------------------------------------------------35o

o

-< 340

- 330

~ 320 I

~ 310

-; 290

//~-----______ ~ 300

~, I

~==-_______ ---='----------__,_---__ r~80

2 4 6 8 10 12 14 16 18 20 22 24

Time (Hours)

- Viscosity -+- Sa.mple Temp. -+- Tank Temp.

1 270

~ 260

ASPHALT RUBBER STORAGE CHARACTERISTICS Pensacola. Florida

Viscosity (Poises) Temperature (Degrees Fl 10r---'--'----------------------------~--------------350

--------_._--_. --' 340

8 -------- -i 330

6 f-i:c:----- -------;:;;;;-~-~"'''='-''::'' =~:====~ ] ~~~ . ~ 300

_____ .. ______ -I 290

.---+-----;-------,. J 280

2 - .. --.--.. ------ 1270

! 260

0~---------L-----------L-----------L-----------~250

o 24 48

Time (Hours)

- Viscosity -.- Sample Temp. - Tank Temp.

Figure 5 Asphalt-Rubber Storage Characteristics

21

96

9.0r----------------------,

fa 7.0 ~ o Il.

~ 6.0 en o u en :; 5.0

4.0

Viscosity Poises = 54.14 • 0.169 Temperature R2 = 0.79

280 290

SAMPLE TEMPERATURE - F 300

Figure 6 Sample Temperature Effect on the Viscosity of Asphalt-Rubber with 12%, 80 Mesh, GTR

22

Separation of GTR from the blended binder can occur during heated storage

unless some form of agitation is provided. In Pensacola the mechanical stirrer

in the blending unit was used to provide agitation for 15 minutes prior to sam­

pling. Separation in tank trucks from the terminal to the asphalt plant should

be minimal because of the relatively short time in transit and the improved stor­

age stability achieved with the finer GTR. At the asphalt plant the hot storage

tanks should have a circulation and/or mechanical stirring system which can pre­

vent separation as well as reblend any GTR that separates from the asphalt during

transport from the terminal.

An FOOT laboratory study indicated that 5 and 11 percent of 80 mesh GTR in

an AC-30 could be satisfactorily blended to a uniform dispersion and viscosity

within 15 minutes or less at reasonable blending temperatures. The effect of GTR

content on viscosity at elevated temperatures after blending is illustrated in

Figure 7. These trends indicated that the upper temperature limit for 11 percent

GTR need to be slightly higher than for 5 percent GTR to achieve equivalent vis­

cosities.

In summary, there does not appear to be any major problems associated with

terminal blending, storage, or transport of asphalt-rubber. However, storage

temperatures above 350F should not be used because of the potential degradation

of the GTR. Also, stirring and/or circulation is essential in all asphalt-rubber

binder storage systems to prevent separation of GTR.

TYPE AND AMOUNT OF GTR IN FRICTION COURSE MIXTURES

The type of rubber currently deemed satisfactory for use in asphalt-rubber

friction course mixtures is that produced by ambiently grinding tires to a suit­

able fineness (2). Cryogenically produced rubber is not presently acceptable be­

cause the effect of its smooth faced particulates on blending time and material

properties has not been evaluated.

23

12

10 ....... UI Q) UI

0 8 c.. -> !:: 6 en 0 C,.)

4 en :;

2

0 285 292

Viscosity values taken 20 to 30 minutes after the start of blending

300 325 350 355

TEMPERATURE (F)

Figure 7 FOOT Viscosity Test Results

24

392

The amount and fineness (gradation) of the GTR to be used in asphalt-rubber

blends depends on the application. In dense-graded friction course mixtures, 5.0

percent (by weight of asphalt cement) of GTR passing the No. 50 sieve (e.g., a

nominal maximum 80 mesh) is recommended. In open-graded friction courses, 12.0

percent (by weight of asphalt cement) of GTR passing the No. 40 sieve (e.g., a

nominal maximum of 60 or 80 mesh) is recommended. Open-graded mixtures are more

tolerant to larger rubber particulate size (e.g., a nominal maximum of 30 mesh)

and greater GTR contents. A limit of 12 percent GTR in binders for open-graded

friction course mixtures has been selected based upon the test results from the

demonstration projects and laboratory tests. Although it may be feasible to in­

crease the GTR content above this amount, the potential for construction problems

and poor in-service performance may increase, particularly on interstate and

other heavily traveled pavements.

ASPHALT-RUBBER MEMBRANE INTERLAYER

Another paving application of GTR is in the asphalt-rubber binder for an

asphalt-rubber membrane interlayer (ARMI). In this case about 0.6 gal/sq.yd of

asphalt-rubber is sprayed over the prepared pavement surface and uniformly sized

aggregates are spread and rolled into the membrane prior to placement of the as­

phalt concrete structural layers. This asphalt-rubber blend uses 20 percent (by

weight of asphalt cement) of GTR passing the No. 10 sieve (e.g., a nominal maxi­

mum 20 mesh). This provides a membrane that will seal the pavement from intru­

sion of moisture and retard the development of reflective cracking in the asphalt

concrete overlay.

Since the ARMI is blended and applied to the old pavement from a distribu­

tor truck within six hours or less, the storage time is sufficiently short to

prevent degradation of the GTR when blending temperatures are above 335F. Higher

blending temperatures (up to 375F) may be required to keep the blending time rea­

sonable with the larger GTR particulates. If time permits, it is desirable to

25

blend the GTR at temperatu-gs in the 335F to 350F range. As an option finer GTR

many be used to reduce blending time. However, this produces an increase in

binder viscosity which may affect discharge (sprayability) from distributor truck

spray nozzles.

The viscosity of the GTR modified asphalt binder will influence spray­

ability according to nozzle opening size and pressure used during the application

process. ViscQsity is not always an indicator of uniform sprayability, but ex­

perience indicates that when it exceeds 40 pOises uniform application may become

difficult (9). The viscosity test results from an FOOT study indicated that vis­

cosity should not be a problem with 20 percent GTR regardless of whether 24, 40,

or 80 mesh GTR is used in the ARMI. However, this is based upon limited informa­

tion and test data. Consequently, some flexibility in the formulation of asphalt­

rubber blends, use of a diluent, or development of a sprayability test may be

needed to correct and/or identify problems with distributor spraying.

The reduction in viscosity produced by'using excessively soft grades of

asphalt cement or diluents that are excessively slow in volatilizing can detract

from the effectiveness of an ARMI layer. Consequently, it is recommended that

a sprayability test be developed for the evaluation of asphalt-rubber membrane

interlayer blends at test temperatures of 330F and 350F. Secondly, it would be

eventually desirable to determine the best parameters for assessment of ARMI be­

havioral properties at in-service temperatures to achieve the desired performance

and longevity. This could result in the development or adoption of test method(s)

for evaluation of the selected engineering parameters.

ENVIRONMENTAL ASPECTS OF ASPHALT-RUBBER

The use of GTR in asphalt for hot mix and ARMI applications does not pose

any problems from an environmental standpoint provided the material is not over

heated. Extended heating at high temperatures or excessively high temperatures

26

(e.g., 400F) may result in a degradation of the GTR with release of S02 as well

as loss of asphalt volatiles. Also this would degrade the quality of the asphalt­

rubber blend. Consequently, the specifications, as presented in a subsequent

section of this report, are believed to be conservative with respect to time­

temperature aspects of blending and storage.

A report on emi ssi ons i ncl udi ng hot-mi x operat ions was submitted by the

FOOT to the Florida Department of Environmental Regulation (OER) Bureau of Air

Regulation for their review and action. Their response stated that the Bureau

had no objections to the FOOT's use of Asphalt-Rubber Friction Courses and

Asphalt-Rubber Membrane Interlayer in Florida (10). This was based on the re­

sults obtained from the monitoring of asphalt cement with and without rubber and

during hot-mix plant production of both conventional and asphalt rubber mixtures

where no difference in emissions could be detected.

SPECIFICATIONS FOR ASPHALT-RUBBER HIGHWAY CONSTRUCTION APPLICATIONS

The FOOT State Material s Office has previously prepared tentative or devel­

opmental specifications for rubber modified asphalt binder (8). These specifica­

tions have been revised and are currently in the FOOT review process. Since

rubber modified asphalt for highway applications is a new and a developing tech­

nology for the State of Florida, the specifications, as presented here, should

not be considered as a final document. It is probable that experience gained

during the 1992 and 1993 construction seasons will identify the need for minor

changes and improvement in the specifications.

Since the term 'Asphalt-Rubber' as defined in D8-91 by ASTM stipulates a

minimum GTR content of 15 percent, the FOOT has changed to the term "Rubber Modi­

fied Asphalt Binder.' Therefore, the FOOT specifications given in the Appendices

use this revised terminology.

27

Appendix A presents Section 919 "Ground Tire Rubber for Use in Rubber Modi­

fied Asphalt Binder." This section set forth the physical, chemical, packaging,

and certification requirements. Three gradations (Types A, B, and C) are speci­

fied for use in rubber modified asphalt binders, or in binders for Asphalt-Rubber

Membrane Interlayers. The intent of the specification was to minimize GTR parti­

cle size interference in dense- and open-graded friction course mixtures by

keeping the amount and size dQwn to what was considered a reasonable level.

Section 336 of the specifications (Appendix B) sets forth the amount of GTR and

the blending requirements for the different friction course mixtures and ARMI.

Section 337 of the specifications on "Asphaltic Concrete Friction Courses'

was modified, as presented in Appendix C, to substitute the use of rubber modi­

fied asphalt binders for standard asphalt cement binders in the construction of

friction courses. It is anticipated that all friction course construction proj­

ects will be utilizing the rubber (GTR) modified asphalt binders by some time in

1993. In the interim period continued use of 1atex additives in the binders for

friction course mixtures may be used until phased out in lieu of the GTR addi­

tive. Appendix D presents Section 918 of the specifications pertaining to

'Asphaltic Concrete - Latex Additive' as modified to allow for the substitution

of GTR modified asphalt binders.

The specification for friction courses in Appendix C has several key pro­

visions. First, Section 337-6.1 stipulates that asphalt-rubber binder contents

be determined for acceptance by calculation using the printouts of weights from

automatic batch plants and in all other cases the binder content will be based

upon quantities from a certified flow meter. Secondly, mix temperatures between

275F and 310F (target of 290F) are slightly higher than the conventional open­

graded friction course (FC-2) mixtures (230F to 310F) without GTR. Dense-fric­

tion course mixtures (FC-l and FC-4) with 5 percent GTR modified asphalt are

28

specified to be produced at temperatures between 290F and 325F (target of 310F).

Other aspects of the specification are fairly standard.

Append i x E presents Sect ion 341 for "Rubber Mod i fi ed Asphalt Membrane

Interlayer." Important features of this specification include the restriction

that the binder should not be held at temperatures over 325F for more than six

hours. This is intended to prevent degradation of the GTR and rubber modified

asphalt binder.

PROJECTIONS FOR THE UTILIZATION OF GROUND TIRE RUBBER

There is a tendency by some individuals and groups to consider asphalt con­

crete pavements as an ideal disposal site for many waste materials and waste by­

products. Unfortunately thi s att itude often preva i 1 s without any thought or con­

cern about the waste materials' effect on quality of the paving material. The

FOOT has approached the use of GTR from the standpoint of improving highway

pavi ng materi a 1 s to provi de better pavements with i n the range of reasonable 1 ife­

cycle costs. Consequently, the previously discussed rubber modified asphalt

binders utilize GTR percentages considered applicable to existing friction course

mixtures and conventional construction procedures.

Approximately 20 to 30 percent of all hot-mix tonnage involves friction

course mixtures. Estimated annual production of open- and dense-graded friction

course, and the number of 1 ane mi 1 es of crack re 1 i ef i nterl ayer were used to pro­

ject the yearly consumption of GTR for highway applications. These calculations

and the estimated total usage of GTR per year are:

Open-Graded Friction Course (FC-2): 640,000 Tons/Yr. x 7.6% Asphalt Binder

46,640 Tons Binder/Yr. x 12% Rubber (GTR) ~

Dense-Graded Friction Course (FC-l & 4):

160,000 Tons/Yr. x 6.8% Asphalt Binder ~

10,880 Tons Binder/Yr. x 5% Rubber (GTR)

29

Rubber Tons/Yr. 46,640 Tons/Yr.

5837

10,880 Tons/Yr. 544

Asphalt-Rubber Membrane Interlayer:

7040 s. Y. '1 x 0,6 Gal, x20% Rubber (GTR) = Lane M~ e S. y,

3.6 Tons R~ber x600 Lane Miles = Lane M~le Yr.

Pavement Marker Adhesive. Joint Filler, Railroad Crossing Pads, Guardrail Spacers:

Tons 3 . 6 -=---"-'-=:-:-0-

Lane Mile

2160

Total Estimated Tons of GTR used by FOOT per year -1000

9544

This tonnage is about 20 percent of the total yearly generation of rubber

from waste tires in Florida. The total was estimated to be 48,750 tons of GTR

per year (8). Since the amount of asphalt concrete used by cities, counties, and

developers exceeds that used by the FOOT on an annual basis, it was assumed that

their demand for GTR would approach or exceed that of the FOOT. Their utiliza­

tion of GTR in applications other than hot-mix is questionable. Therefore, the

yearly use of GTR could range between 15 to 20 percent or more of the yearly gen­

eration. This indicates that about 40 percent of the waste rubber generated each

year may be utilized in our highway transportation system. The remaining 60 per­

cent plus waste tire stock piles need to be consumed in other types of processes

such as burning for heat or production of electricity or recycled into new tires

or rubber products.

An article in the February 1992 issue of "Engineering Times" implies that

of the 242 million tires scrapped in the U.S.A. each year only 22 percent are

disposed of by means other than in landfills, stockpiling or illegal dumping

(II). Of this 22 percent only 6 percent is recycled and about 10 percent is used

for fuel. Since new tires contain less than 2 percent recycled rubber there is

currently not sufficient demand to affect the waste tire disposal problem. At

this time less than one percent of scrap tires find their way into asphalt

30

binders. This overview gives a dim picture of the progress made in handling

waste tire utilization.

Currently in Florida, waste tires are being shredded for use in power gen­

eration at a pulp and paper plant in Georgia. The shredded tires combined with

approximately equal amounts of wood waste produces sufficiently high BTU and ade­

quate combustion to serve as a fuel base for this operation. It has been esti­

mated that if pulp and paper companies in Florida were similarly equipped to burn

shredded tires their demand would be about equal to the current generation of

waste tires. Shredded tires can also be used as a supplementary fuel for cement

kilns operating in Florida.

This is not meant to imply all waste tires should be incinerated but rather

to illustrate that utilization could rapidly increase resulting in a high demand

for waste tire rubber with subsequent changes in cost impacting the economics of

any process us i ng waste rubber. Therefore, in the long term only those uses

which greatly benefit from the use of this rubber will be economically viable.

31

LISTING OF REPORTS PERTAINING TO FOOT ASPHALT-RUBBER INVESTIGATIONS

1. K. H. Murphy, C. F. Potts, "Evaluation of Asphalt-Rubber As a Stress Absorbing Interlayer and As a Binder for Seal Coat Construction (SR-60 Hillsborough County)." Demonstration Project No.37, FHWA-DP-27-14, June 1980, pp. 1-28.

2. F.L. Roberts, P.S. Kandhal, E.R. Brown, and R.L. Dunning, "Investigation and Evaluation of Ground Tire Rubber in Hot-Mix Asphalt," National Center for Asphalt Technology, Auburn University, Alabama, August 1989, pp. 1-172.

3. B.E. Ruth, S. Sigurjonsson, and C.L. Wu, "Evaluation of Experimental Asphalt-Rubber, Dense-Graded, Friction Course Mixtures: Materials and Con­struction of Test Pavements on N.E. 23rd Avenue, Gainesville, Florida," Technical Report, U.F. Project No. 4910450426912, Department of Civil Engineering, University of Florida, May 1989, pp. 1-161.

4. B.E. Ruth, "Evaluation of Experimental Asphalt-Rubber, Open-graded, Fric­tion Course Mixtures: Materials and Construction of Test Pavements on State Road 16," Technical Report, U.F. Project No. 4910450426912, Depart­ment of Civil Engineering, University of Florida, November 1989, pp. 1-56.

5. G.C. Page, "Florida's Initial Experience Utilizing Ground Tire Rubber in Asphalt Concrete Mixes," Research Report FL/DOT/M089-366, State of Florida Department of Transportation, Materials Office, September 1989, pp. 1-31.

6. R.C. West, J.A. Musselman, "Extraction Testing of Asphalt Concrete Mix­tures Containing Ground Tire Rubber," Bituminous Materials Study 89-4, Florida Department of Transportation, Materials Office, June 16, 1989, pp. 1-7.

7. B.E. Ruth, "Documentation of Open-Graded, Asphalt-Rubber Friction Course Demonstration Project on Interstate 95, St. Johns County," Technical Report, U.F. Project No. 4910450429812, Department of Civil Engineering, University of Florida, December 1990, pp. 1-28.

8. B.E. Ruth, "Evaluation of Ground Tire Rubber in Asphalt Concrete - Execu­tive Summary of Information Compiled from Investigations and Demonstration Projects" Technical Report, U.F. Project No. 4910450429812, Department of Civil Engineering, University of Florida, January 1991.

9. Personal communication to L.L. Smith, State Materials Engineer, Florida Department of Transportation, in a letter dated February 14, 1992 from Anne Stonex and Kent R. Hansen of International Surfacings, Inc., Chandler, Arizona.

10. Personal communication to K.H. Murphy, State Bituminous Engineer, FOOT, in a letter dated August 20, 1991 from C.H. Favey, Chief, Bureau of Air Regu­lation.

11. Engineering Times, February 1992; "Scrap Tires in America Fail Reuse Promise," p.7.

32

APPENDIX A

SECTION 919 - GROUND TIRE RUBBER FOR USE IN RUBBER

MODIFIED ASPHALT BINDER

33

SECTION 919 GROUND TIRE RUBBER FOR USE IN RUBBER MODIFIED ASPHALT BINDER

919-1 Description.

This specification governs ground tire rubber for use in rubber modified asphalt binders for use in a variety of paving applications.

919-2 General Requirements.

The ground tire rubber shall be produced by ambient grinding methods. The rubber shall be sufficiently dry so as to be free flowing and to prevent foaming when mixed with asphalt cement. The rubber shall be substantially free from contaminants including fabric, metal, mineral, and other non-rubber sUbstances. Up to four percent (by weight of rubber) of talc (such as magnesium silicate or calcium carbonate) may be added to prevent sticking and caking of the particles.

919-3 Physical Requirements.

919-3.1 Gradation: The sample shall be tested in accordance with FM 1-T 027 (AASHTO T 27) with the following exceptions: a 100g sample size and up to 25% dusting agent (talc). (Rubber balls may also be used to aid in the sieving of finely ground rubber.) The resulting rubber gradation shall meet the gradation limits shown in Table 919-1 for the type of rubber specified.

919-3.2 Specific Gravity: The specific gravity of the rubber shall be 1.15 ± 0.05 when tested in accordance with ASTM D-297, pycnometer method.

919-3.3 Moisture Content: The moisture content shall be determined in accordance with AASHTO T 255, with the exception that the oven temperature shall be 140 ± 5°F and the weight of the sample shall be 50g. The moisture content shall not exceed 0.75% by weight.

919-3.4 Metal contaminants: particles shall be detected when through a 50g sample.

919-4 Chemical Requirements.

No more than 0.01% metal thoroughly passing a magnet

The chemical composition of the ground tire rubber shall be determined in accordance with ASTM D 297 and shall meet the following requirements:

Acetone Extract - Maximum 25 percent. Rubber Hydrocarbon Content - 40 to 55 percent. Ash Content - Maximum 8 percent.*

34

Carbon Black Content - 20 to 40 percent. Natural Rubber - 16 to 34 percent. * 10 percent for Type A rubber

919-5 packaging and Identification Requirements.

The ground tire rubber shall be supplied in moisture resistant packaging such as either disposable bags or other appropriate bulk containers. Each container or bag of ground tire rubber shall be labeled with the manufacturer's designation for the rubber and the specif ic type, maximum nominal size, weight and manufacturer's batch or lot designation.

919-6 Certification Requirements.

The manufacturer of the ground rUbber shall furnish the Engineer certified test results covering each shipment of material to each project. These reports shall indicate the results of tests required by this specification. They shall also include a certification that the material conforms with the specification, and shall be identified by manufacturer's batch or lot number.

Table 919-1 Gradations Of Ground Tire Rubber

sieve Size % Passing

10 20 30 40 60 80

100 200

Type A

100 98-100 90-100 70-90 35-60

35

Type B

100 95-100 85-100 30-60 15-40 5-25

Type C

100 85-100 40-65 20-45

5-20

APPENDIX B

SECTION 336 - RUBBER MODIFIED ASPHALT BINDER

36

SECTION 336 RUBBER MODIFIED ASPHALT BINDER

336-1 Description.

This specification governs the production of rubber modified asphalt binder for use in Asphaltic Concrete Friction Courses and Rubber Modified Asphalt Membrane Interlayers.

336-2 Materials.

336-2.1 Asphalt Cement: The particular grade of asphalt cement as specified in Table 336-1 for the respective uses shall meet the requirements of section 916.

336-2.2 Ground Tire Rubber: The type of ground tire rubber shall meet the requirements of Section 919.

336-3 Rubber Modified Asphalt Binder.

The asphalt cement and ground tire rubber shall be thoroughly mixed and reacted in accordance with the requirements of Table 336-1. The rubber type shall be in accordance with the approved design mix. The blending unit may be a batch type or continuous type and shall provide for sampling of the blended and reacted rubber modified asphalt binder material during normal production. Blending of the asphalt cement and ground tire rubber may be accom­plished either at the asphalt supplier's terminal or at the project site.

336-4 Equipment.

The meter for the rubber modified asphalt binder will be certified to meet the requirements for accuracy, condition, etc., of the Bureau of Weights and Measures of the Florida Department of Agriculture and such fact shall be recertified every six months either by the Bureau of Weights and Measures or by a registered scale technician.

336-5 Testing and certification Requirements.

336-5.1 Blending at Project site: The ground tire rubber content in the rUbber modified asphalt binder will be monitored by the Department on a daily basis based on the following: (1) the weight of the ground tire rubber used, and the gallons of asphalt-rubber binder used (The weight per gallon for the various types of rubber modified asphalt binder shown in Table 336-1 are to be used for these calculations.) or (2) the weight of the ground tire rubber used and the number of gallons of asphalt cement used. The quantity of rubber modified asphalt binder used shall be determined by a certified meter meeting the requirements of 336-4.

336-5.2 Blending at Asphalt Supplier's Terminal: Where the rubber modified asphalt binder is blended at the asphalt supplier's

37

terminal, each load delivered to the project site shall be certified that the rubber modified asphalt binder has been produced in accordance with and meets the requirements of 336-3. In addition, the certification shall include the certification requirements for the asphalt cement, and ground tire rubber, as specified in 916-1.2 and 919-6, respectively.

336-5.3 Testing of Rubber Modified Asphalt Binder: modified asphalt binder will be tested for the requirement of Table 336-1 by the Department at the frequencies and situations:

The rubber viscosity following

(1) One per batch (for batch blending) or one per day (for continuous blending) during blending at the project site.

(2) Each load when blended at the asphalt supplier's terminal.

(3) Beginning of each day from the storage tank when the asphalt-rubber binder is stored at the project site.

If the rubber modified asphalt binder does not meet the minimum viscosity requirement it will be rejected for use.

38

Uses

Table 336-1

Rubber Modified Asphalt Binder

Dense-graded Friction

Course

Open-graded Rubber Modified Friction Asphalt Course Membrane

Interlayer

Rubber Type Type A Type B Type C (or A)* (or B or A)*

% Ground Tire Rubber 5 12 20 (by wt. of asphalt cement)

AC Grade AC-30 AC-30 AC-20

Min. Temperature 300 300 335 (oF)

Max. Temperature 335 350 375 (oF)

Min. Reaction Time, 10 15 30 (Minutes) (for Type B) (for Type C)

unit Weight ** 8.6 8.7 8.8 (lbs / gal)

Min. Viscosity, *** (Poises)

3.0 @ 3250p 6.0 @ 325°F 15.0 @ 350°F

NOTE:

* Use of finer rubber could result in the reduction of the minimum reaction time.

** Conversions to standard 60°F are not necessary. *** FM 5-548, Viscosity of Rubber Modified Asphalt by use

of the Rotational (Dip-N-Read) Viscometer.( See Appendi x F.)

The minimum reaction time may be adjusted if approved by the state Materials Office depending upon the temperature, size of the ground tire rubber and viscosity measurement determined from the rubber modified asphalt binder material prior to or during production. The asphalt-rubber binder for use in membrane inter layers shall be applied within a period of six hours unless some form of corrective action such as cooling and reheating is approved by the state Materials Office.

39

APPENDIX C

SECTION 337 - ASPHALTIC CONCRETE FRICTION COURSES

40

SECTION 337 ASPHALTIC CONCRETE FRICTION COURSES

(RUBBER MODIFIED ASPHALT BINDER)

337-1 Description.

This section specifies the materials, composition, job mix formula and compensation for Asphaltic Concrete Friction Courses containing rubber modified asphalt binder. The plant and equipment requirements for this pavement are specified in section 320. General construction requirements for all asphaltic concrete pavements as specified in section 330 are applicable to this Section, subject to any exceptions contained herein.

The work will be accepted on a LOT by LOT basis in accordance with the applicable requirements of sections 5, 6, and 9. The size of the LOT for the bituminous mix accepted at the plant will be as specified in 331-5, and for the material accepted on the roadway as stipulated in 330-10 and 330-12.

The mixes covered by this section are designated as Friction Course 1 (FC-1), Friction Course 2 (FC-2), and Friction Course 4 (FC-4) .

337-2 Materials.

337-2.1 General: The materials used shall conform with the requirements specified in Division III as modified herein.

337-2.2 Rubber Modified Asphalt Binder: The rubber modified asphalt binder shall meet the requirements of section 336.

337-2.3 Coarse Aggregate: Except as modified herein, all coarse aggregate shall meet the requirements of Section 901.

337-2.4 Fine Aggregate:

337-2.4.1 General: Fine aggregates shall meet all applicable requirements of section 902.

337-2.4.2 Special Requirements for FC-1: (a) Local Materials: If clay is present in the fine

aggregate, the quantity shall not exceed seven percent and it shall be of a type which will not produce clay balls in the mixture. The sand shall be nonplastic and shall be suitable for use in bituminous mixtures as determined by laboratory tests. If the sand deposits consist of stratified layers of varying characteristics and gradation, the Contractor shall employ such means as necessary to secure uniform material. The fine aggregate will be sampled at the asphalt plant.

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(b) screenings: Slag, granite and gravel or any combination of these materials shall be crushed and meet the following gradation requirements in addition to the requirements in 902-5.

sieve Size

1/2" No. 10 No. 200

Percent Passing

100 40-75

0-13

337-2.4.3 special Requirements for FC-4: Fine aggregate shall be composed of quartz grains and shall be reasonably free from lumps, clay, soft or flaky particles, salt, alkali, organic matter, loam or other extraneous substances. only approved fine aggregate sources located above parallel 27 degrees, 30 minutes, in the state of Florida will be acceptable for use in FC-4 mixes. The weight of extraneous substances shall not exceed the following percentages:

Material passing No. 200 Sieve Shale . . . . . Coal and Lignite Clay Lumps ... Cinders and Clinkers

4.0 1.0 1.0 1.0 0.5

In addition, the total amount of all the above materials in the fine aggregate shall not exceed five percent.

Fine aggregate, excluding crushed stone screenings, shall be subjected to the colorimetric test for organic impurities, and if the color produced is darker than the standard solution, the aggregate shall be rejected unless it can be shown by appropriate tests that the impurities causing the color are not of a type that would be detrimental to the pavement. Such tests shall be in accordance with FM l-T 071 and AASHTO M-6.

Fine aggregate shall be reasonably well-graded, from coarse to fine and when tested by means of laboratory sieves, it shall meet the following requirements, in percent of total weight passing:

sieve Size

No. 4 No. 10 No. 40 No. 80 No. 200

Percent Passing

95-100 80-100

10- 40 0- 10 0- 4

The above gradation for fine aggregate represents the extreme limits which will be used in determining the suitability for use of sand from all sources of supply. The gradation of fine aggregate from anyone source shall be reasonably uniform and not subject to the extreme range specified above. For the purpose of

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determining the degree of uniformity of fine aggregate, fineness modulus determinations shall be made upon representative samples of fine aggregate submitted by the Contractor from such sources as they propose to use. Fine aggregate from anyone source having a variation in fineness modulus greater than 0.20 either way from the fineness modulus of the representative sample submitted by the Contractor may be rejected.

337-2.5 Crushed stone screenings: Any screenings used in the combination of aggregates shall contain not more than 15 percent of material passing the No. 200 sieve. When two screenings are blended to produce the screenings component of the aggregate, one screening may contain up to 18 percent of material passing the No. 200 as long as the combination of the two does not contain over 15 percent material passing the No. 200 sieve. Screenings may be washed to meet these requirements. Crushed stone screenings used in friction course mixes shall meet the requirements of Section 902.

337-3 General Composition of Mixes.

337-3.1 General: The bituminous mix shall be composed of a combination of aggregate (coarse, fine, or a mixture thereof), mineral filler if required, and rubber modified asphalt Binder. The several aggregate fractions shall be sized, uniformly graded and combined in such proportions that the resulting mix will meet the grading and physical properties of the approved mix design.

337-3.2 Aggregate Components: The aggregate components of the various mixes set out in this section shall be as follows:

FC-1: Either crushed slag, crushed gravel or crushed granite, any combination of these aggregates or a combination of one or more of these aggregates with fine aggregate. The coarse aggregate component (crushed slag, crushed gravel or crushed granite) shall comprise at least 60 percent of the aggregate combination.

FC-2: Either crushed granite, crushed slag, crushed gravel or a combination of these. Crushed limestone from the Oolitic formation will also be permitted if the coarse aggregate contains a minimum of 12 percent non-carbonate material as determined by FM 5-510 and approval of the source is granted by the state Materials Office prior to its use. In addition, use of aggregates other than those listed above may be permitted if approved by the State Materials Office.

FC-4: A blend of fine aggregate and crushed limestone screenings, with the fine aggregate comprising 50 to 70 percent of the total aggregate in the mix. The combined aggregates in the mix shall contain a minimum of 50 percent acid insoluble materials

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as determined by the FM 5-510. All aggregate materials shall be furnished from DOT approved sources.

continuing approval of all sources of material for use in FC-1, FC-2 and FC-4 will be based on field performance.

337-3.3 Grading Requirements: The mix design, as established by the Contractor and approved by the Department, shall be within the design range specified in Table 331-1 for all friction course mixes.

337-4 Mix Design.

The mix design shall conform to the requirements of 331-4.3 of these specifications except that Item No.7 in 331-4.3.1 shall not apply to FC-2. Data shall be submitted showing that the mix design meets the requirements of Table 331-2 using conventional AC-30. The rubber modified asphalt will then be sUbstituted at the optimum conventional binder content for production and shall be shown as the optimum binder content on the approved mix design.

337-5 Contractor's Quality Control.

The Contractor shall provide the necessary quality control of the friction course mix and construction in accordance with the applicable provisions of 6-8.4 and 331-4.4. After the mix design has been approved, the Contractor shall furnish the material to meet the approved mix design in accordance with the provisions of 331-4.4.2 and Table 331-3. Plant calibration shall comply with the provisions of 331-4.4.3 and Table 331-3.

337-6 Acceptance of Mix.

337-6.1 Acceptance at the Plant: The friction course mix shall be accepted at the plant with respect to gradation in accordance with the applicable requirements of 331-5. Acceptance determinations for rubber modified asphalt binder content for mixtures produced by automatic batch plants with printout will be based on the calculated binder content using the printouts of the weights of rubber modified asphalt binder actually used. In all other cases, acceptance determinations for rubber modified asphalt binder content will be based on calculated binder content using a reading from the certified meter meeting the requirements of 336-4 and the quantity of mix produced. Payment will be made based on the provisions of Table 331-6. In this table, the asphalt cement content (printout) shall be used for rubber modified asphalt binder.

337-6.2 Acceptance on the Roadway: The friction course mix will be accepted on the roadway with respect to density and surface tolerance in accordance with the applicable provisions of 330-10 and 330-12. There will be no density requirements for FC-2.

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337-6.3 Additional Tests: apply to the friction courses

The provisions of FC-1, FC-2 and FC-4.

337-7 Special construction Requirements.

337-7.1 Temperature Requirements for FC-2:

331-5.5 shall

337-7.1.1 Air Temperature at Laydown: The mixture shall be spread only when the air temperature (the temperature in the shade away from artificial heat) is at or above 60°F.

337-7.1.2 Temperature of the Mix: The rubber modified asphalt binder and aggregates shall be heated and combined in such a manner as to produce a mix having a temperature, when discharged from the pugmill, within the range of 275°F and 310°F. The target temperature will be 290°F. All other requirements of 330-6.3 shall apply to FC-2.

337-7.2 Temperature Requirements for FC-1 and FC-4:

337-7.2.1 Air Temperature at Laydown: The mixture shall be spread only when the air temperature (the temperature in the shade away from artificial heat) is at or above 60°F.

337-7.2.2 Temperature of the Mix: The rubber modified asphalt binder and aggregates shall be heated and combined in such a manner as to produce a mix having a temperature, when discharged from the pugmill, within the range of 290°F and 325°F. The target temperature will be 310°F. All other requirements of 330-6.3 shall apply to FC-1 and FC-4.

337-7.3 Compaction of FC-2: only seal rolling will be required; this rolling will be accomplished using a tandem steel­wheel roller. The weight of the steel-wheel roller shall not exceed 135 pounds per linear inch (PLI) of drum width.

PLI = Total Weight of Roller (pounds)

Total width of Drums (inches)

A small amount of liquid detergent may be added to the water in the roller to reduce adhesion to the drum. Rolling shall be accomplished with a single coverage and with a nominal amount of overlap. In no case shall a roller be allowed on the mat after the seal rolling has been completed.

Where the lane being placed is adjacent to a previously laid mat, the longitudinal joint will not be pinched in a manner with the roller on the cold mat. The longitudinal joint will be pinched with the roller on the mat being rolled, overlapping onto the cold mat by no more than three inches.

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At intersections and in other areas where the pavement would be subjected to traffic before it has a chance to cool, the surface of the approaching pavement shall be sprayed with water so that the tires of the vehicles are wet prior to crossing over the compacted mat.

337-7.4 Compaction of FC-1 and FC-4: A small amount of liquid detergent may be added to the water in the roller to reduce adhesion to the drum.

At intersections and in other areas where the pavement would be subjected to traffic before it has a chance to cool, the surface of the approaching pavement shall be sprayed with water so that the tires of the vehicles are wet prior to crossing over the compacted mat.

337-7.5 Thickness of Friction Courses:

337-7.5.1 General: The thickness of the friction course shall be designated in the plans. This is the minimum desirable thickness for FC-1 and FC-4, and the maximum desirable thickness for FC-2. The minimum spread rate for FC-2 shall be 25 pounds per square yard when lightweight aggregates are used and 40 pounds per square yard when conventional aggregates are used.

337-7.5.2 Thickness Requirements - Square Yard Payment: The thickness shall be determined in accordance with 330-15.1 except that the average thickness will not be calculated. Cores will not be taken in areas where the friction course is being transitioned in thickness to tie into an existing surface. The maximum allowable deficiency from the thickness specified in the plans shall be 1/4 inch. If any area is deficient in thickness by more than the allowable tolerance, the Contractor shall correct the deficiency by removing and replacing the friction course at the proper thickness or by overlaying with additional friction course mix. The overlay shall extend 50 feet either side of the deficient area and shall extend across the full width of the roadway.

As an exception to the foregoing, if the Engineer determines that the friction course will satisfactorily perform its intended function without corrective work, the friction course may be left in place without compensation. The area for which no payment will be made shall be the product of the total distance between cores indicating thickness within tolerances and the width of the lane which was laid in the particular pass in which the deficient thickness occurred. Additional cores will be taken as necessary to define the limits of a deficiency. open-graded friction courses will not be cored for thickness determinations.

337-7.6 Hot storage of FC-2 Mixes: When surge or storage bins are used in the normal production of FC-2, as with the drum mixer plants, the maximum time the mix is allowed to remain in the surge or storage bin shall not exceed one hour.

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337-7.7 Longitudinal Grade Controls for Open-Graded Friction Courses: On open-graded friction courses, the use of the longitudinal grade control (skid, ski, or traveling stringline) is prohibited. The use of the joint matcher is required.

337-7.8 Paving of Adjacent four-foot Wide Shoulders: When construction includes the paving of adjacent four-foot wide shoulders, the mainline pavement and the shoulder shall be paved in a single pass.

337-8 Method of Measurement.

The area to be paid for shall be plan quantity subject to 9-3.2. The pay area shall include entire areas of transitions to tie into existing pavement but excluding areas for which no payment is to be made due to deficient thickness as defined in 337-7.5. No adjustment to the area to be paid for will be made for extra thickness or deficient thickness.

337-9 Basis of Payment

337-9.1 Rubber Modified Asphalt Binder: The bid price for the friction course mix shall include the cost of the asphalt cement, ground tire rubber, anti-stripping agent and blending and handling of the rubber modified asphalt binder in the friction course mix. The bid price for the friction course shall be based on the following rubber modified asphalt binder contents:

Mix Tvpe

FC-1 FC-2 FC-4

Rubber Modified Asphalt Binder Content (%)

by weight of total mix.

6.0 7.6* 7.0

*14.6 for FC-2 with lightweight aggregate.

If the rubber modified asphalt binder content in the approved mix design increases or decreases from the foregoing percentages, the bid price of the mix will be adjusted based on the invoice price of the rubber modified asphalt binder material plus ten percent of the invoice price. When the rubber modified asphalt binder is blended at the asphalt plant, the invoice price will be a combination of the invoice price for the asphalt cement, the ground tire rubber and the blending of the rubber modified asphalt binder.

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where

Adjustment ($/sy) = t (ACDeSign-ACTable) 100lb/ sy-in (IP) 1.10 8. 6lb/ gal

ACT,",', = Asphalt Content (%) from above table, AC~.~ = Asphalt Content (%) in the mix design, as issued by

the Materials Office, t = Design Thickness (inches). IP = Invoice Price

As an example, when the rubber modified asphalt binder content for a FC-1 mix is determined to be 6.8 percent the adjustment shall be calculated as follows:

$ Per square yard = t x (.005 x 100 lb/sy-in / 8.6 lb/gal) x Invoice Price x 1.10

where AC~,~-ACT'"'Ie=. 065-.060=.005,

and other variables are defined above.

*For FC-2 the lb/sy-inch will be based on the average spread rate for the project, and the thickness will not be needed.

The contract unit price per square yard for Asphaltic Concrete Friction Course shall be full compensation for all the work specified under this Section.

Payment shall be made under: Item No. 337-5 - Asphaltic Concrete Friction Course

- per square yard.

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APPENDIX D

SECTION 918 - ASPHALTIC CONCRETE - LATEX ADDITIVE

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SECTION 918 ASPHALTIC CONCRETE - LATEX ADDITIVE

918-1 Description.

Th i s work i nvo 1 ves the p 1 aci ng of asphalt i c concrete mi xtures us i ng a 1 atex modified asphalt binder in accordance with all applicable requirements of the Standard Specifications and the Special Provisions. Asphaltic concrete mixtures using a latex modified asphalt binder shall be placed in areas as shown on the plans.

Use of an asphalt rubber modified asphalt binder meeting the requirements of Section 336, may be substituted in lieu of the latex modified asphalt binder.

918-2 Materials.

Latex Additive: The Latex additive shall conform to the following specifications:

Ionic Character Total Solids (wt. percent) pH Viscosity (Brookfield RVT No.3 Spindle, 20 rpm) cp

Pound/Gallon Monomer Ratio percent

(Styrene/Butadiene)

Anionic 69 ± 0.5 10.5 ± 0.5

1000-2500 7.95 ± 0.5

24/76 ± 1. 0

The Contractor shall furnish vendor's certified test reports for each transport, or equivalent, of latex additive shipped to the project. The report shall be delivered to the Engineer before permission is granted for the use of the material. The furnishing of the vendor's certified test report for the latex additive shall not be interpreted as a basis for final acceptance. All such re­ports shall be subject to verification by testing sample materials as received for use on the project.

Three percent Latex Solids (4.3 percent Latex Emulsion), by weight of as­phalt cement binder material, shall be added to the asphaltic concrete mixture in accordance with the following:

Batch and continuous mix plants: The introduction of the latex shall begin within five seconds of the wet mix portion of the mixing cycle, and be continued simultaneously with the asphalt spray operation. The minimum wet mixing time shall be 50 seconds.

Drum mix plant: The latex shall be introduced into the drum mixer at a point approximately two feet downstream from the point where the asphalt cement is introduced.

The metering device for the latex additive must be accessible to the plant operator and the accuracy of the meter must be approved by the Engineer prior to the start of production.

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The target temperature established for the latex modified asphaltic con­crete mixture shall be 290°F for FC-2 and 310°F for FC-l, FC-4 and Type S mix­tures. Any change in this target temperature must be approved by the District Bituminous Engineer.

NOTE: 1) 2)

3)

Every effort shall be made to minimize hand work. Rolling shall be completed before the mat has cooled to a tempera­ture that will prevent proper compaction. A small amount of liquid detergent may be added to the water in the roller to reduce adhesion to the drum. At intersections and in other areas where the pavement would be sub­jected to cross traffic before it has had a chance to cool, the pavement shall be cooled by spraying water onto the surface immedi­ately after rolling is completed. The method of artificial cooling shall be done in the shortest possible time to minimize a disruption of traffic.

If an asphalt-rubber binder is substituted in lieu of the latex modified asphalt binder~ the requirements in Section 336 and all other relevant specifica­tions shall apply.

918-3 Payment.

The quantity of latex material will not be paid for directly, but shall .be included in the asphaltic items of the contract.

If an asphalt-rubber binder is substituted in lieu of the latex modified asphalt binder, the asphalt-rubber modified asphalt binder will not be paid for directly, but included in the bid price of the friction course mix in accordance with Section 337.

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APPENDIX E

SECTION 341 - RUBBER MODIFIED ASPHALT MEMBRANE INTERLAYER

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SECTION 341 RUBBER MODIFIED ASPHALT MEMBRANE INTERLAYER

341-1 Description.

The work specified in this Section consists of the construction of an rubber modified asphalt membrane interlayer composed of a separate application of rubber modified asphalt binder covered with a single application of aggregate.

341-2 Materials.

341-2.1 Rubber Modified Asphalt Binder: The rubber modified asphalt binder shall conform to the requirements of section 336.

341-2.2 Cover Material: The cover aggregate shall be Size No. 6 stone, slag or gravel meeting'the requirements of section 901, with the modification that 100 percent of the material shall pass the 3/4-inch sieve.

341-3 Equipment.

341-3.1 Power Broom: The power broom for cleaning the existing pavement shall be capable of removing all loose material from the surface. The power broom for cleaning loose aggregate from the finished surface shall be a rotary sweeper type.

341-3.2 Spreading Equipment: The aggregate spreader shall be a self-propelled unit that can be adjusted to accurately apply the cover material at the specified rate and will spread the material uniformly.

341-3.3 Rollers: The rollers used shall be self-propelled, pneumatic-tired traffic type rollers equipped with at least seven smooth-tread, low-pressure tires and capable of carrying a gross load of at least eight tons. The inflation of the tires shall be 90 psi minimum and shall be maintained such that in no two tires shall the air pressure vary more than five psi. The traffic roller shall be loaded as directed by the Engineer.

341-3.4 Mixing Equipment: The mixing equipment for rubber modified asphalt binder shall be designed for that purpose and shall be capable of producing and maintaining a homogeneous mixture of rubber and asphalt cement at the specified temperature.

341-3.5 Pressure Distributor: The distributor used to apply rubber modified asphalt binder shall be a pressure type capable of maintaining a homogeneous mixture of rubber and asphalt cement at the specified temperature and consistently apply the material in a uniform manner.

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341-4 Preparation of Rubber Modified Asphalt Binder.

The materials shall be combined as rapidly as possible for such a time and at such a temperature that the consistency of the binder approaches that of a semi-fluid material. The time and temperature for blending of the rubber modified asphalt binder shall be as specified in Table 336-1. The Engineer shall be the sole judge of when the material has reached application consistency, and will also determine if an extender oil or diluent is needed. After reaching the proper consistency, application shall proceed immediately. In no case shall the mixture be held at temperatures over 325°F for more than six hours after reaching that point.

341-5 Construction Procedure.

341-5.1 Preparation of Surface: rubber modified asphalt binder, the cleaned as specified in 300-4.

Prior to application of the existing pavement shall be

341-5.2 Application of Rubber Modified Asphalt Binder: The rUbber modified asphalt binder shall be applied only under the following conditions:

a) The air temperature is above 60 of and rising. b) The pavement is absolutely dry. c) The wind conditions are such that cooling of the rubber modified asphalt binder will not be so rapid as to prevent good bonding of the aggregate.

The rubber modified asphalt binder shall be uniformly applied, using a pressure distributor meeting the requirements of this specification, at the rate of 0.6 gallon per square yard. The Engineer may vary the rate of application. The application rate is based on pounds per hot gallon as shown in Table 336-1. Conversions to standard 60°F are not necessary.

341-5.3 Application of Cover Material: Immediately after application of the rubber modified asphalt binder, cover material meeting the requirements set out herein shall be uniformly spread at a rate of between 0.26 and 0.33 cubic feet per square yard. The exact rate will be set by the Engineer.

The application of the rubber modified asphalt binder and the application of the cover material shall not be separated by more than 150 feet.

341-5.4 Rolling: In order to ensure maximum embedment of the aggregate, it is imperative that the entire width of the mat be covered immediately by traffic rollers meeting the requirements of this specification. For the first coverage, a minimum of three traffic rollers shall be provided in order to accomplish simultaneous rolling in echelon of the entire width of the spread.

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When spreading is stopped, the spreader shall be moved ahead to allow immediate rolling of all cover material.

Following the first coverage, a minimum of four coverages shall be made with additional traffic rollers.

341-5.5 Traffic Control: The normal sequence of construction operations shall require the first course of asphalt concrete overlay to be placed over the membrane prior to opening to traffic. When this is not possible due to circumstances outside the Contractor's control, he shall terminate placement of the membrane layer as soon as possible to minimize the amount of the layer that will be exposed to traffic. In no case shall traffic be permitted on the membrane layer for a period of at least two hours. Any exposed membrane layer that is left open to traffic shall be covered immediately when the Contractor resumes his normal paving operation. The intent of this specification is to minimize the amount of membrane inter layer material directly exposed to traffic.

341-6 Unacceptable Rubber Modified Asphalt Membrane Interlayer.

If the rubber modified asphalt membrane inter layer is unacceptable due to incorrect blending, application rate, or not meeting the requirements of this Section, or damaged prior to placement of the asphaltic concrete layer, it shall be removed and replaced as directed by the Engineer. In no case shall excessive amounts of rubber modified asphalt binder be allowed.

341-7 Method of Measurement.

The area of Rubber Modified Asphalt Membrane Interlayer shall be determined as provided in 9-1.3.1.

341-8 Basis of Payment.

The quantity of Rubber Modified Asphalt Membrane Interlayer shall be paid at the contract unit price for this item. Such price and payment shall constitute full compensation for all work specified in this Section including furnishing cover materials, asphalt cement, ground tire rubber, and all processing, mixing, handling, spreading, rolling, and other incidental work necessary to complete this item.

payment shall be made under:

Item No. 341-70- Rubber Modified Asphalt Membrane Interlayer -per square yard

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APPENDIX F

FM-548-VISCDSITY OF RUBBER MODIFIED ASPHALT

BY ROTATIONAL (DIP-N-READ) VISCOMETER

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1. SCOPE

Florida Method of Test for

VISCOSITY OF RUBBER MODIFIED ASPHALT BY ROTATIONAL (DIP-N-READ) VISCOMETER

Designation: FM 5-548

FM 5-548 XXX XX

1.1 This test method outlines a procedure for determining the viscosity of rubber modified asphalt by rotational viscometer.

2. REFERENCED DOCUMENTS

2.1 AASHTO Standards:

T 40 (FM 1-T 040) Sampling Bituminous Materials

2.2 ASTM Standards:

E 1 ASTM Thermometers

3. SUMMARY OF METHOD

3.1 The viscosity of the rubber modified asphalt is determined using a rotational viscometer. After the sample is brought to the test temperature, the viscometer rotor is dipped into the sample and rotated at a constant speed. The resistance to rotation of the rotor is measured in Poises.

4. APPARATUS

4.1 Rotational Viscometer - A portable rotational Dip-N-Read ' viscometer.

4.2 Thermometer - Calibrated Iiquid-in-glass, total immersion type, of suitable range with gradations at least every 2.O"F (l.ifC) and a maximum scale error of 2.0"F (l.ifC) as prescribed in ASTM Specification E 1.

4.3 Sampling Container - One-quart double friction-top metal can.

4.4 Hot plate - A thermostatically controlled hot plate capable of maintaining the sample at 350° F (176.7°C).

4.5 Stirring Device - A metal spatula with wood or plastic handle suitable for stirring the sample.

IThe Dip-N-ReAd rotnlionai viscometer ill II. product of Nlltion.nllnstrument Co., Inc .• 4119 Fordlcigh Rd., Baltimore, MD.

21215

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5. PROCEDURE

5.1 Obtain sample in accordance with FM 1-T 040.

FM 5-548 xxx XX

5.2 Using a thermometer determine the temperature of the sample. Heat or cool the sample until the temperature is within the range of 325 ± 1°F (162.8 ± 0.6°C).

Note 1: For viscosity tests on Asphalt-Rubber Membrane Interlayer containing rubber types A, B or C, the viscosity test on this material will be performed within the range of 350 ± 1°F (176.7 ± 0.6°C).

Note 2: Stir the sample to assure uniform temperature throughout the sample.

5.3 After the sample is at the desired test temperature, immediately dip the appropriate rotor into the sample to the required depth of immersion as indicated by the dip mark, on the shaft of the rotor (Note 3).

Note 3: For viscosity readings of 3 - 150 poises use rotor #1 and read the middle scale. For viscosity readings of 0.3 to 15 poises use rotor #3 and read the upper scale .

. Note 4: The viscometer rotor shall be clean and free of any solvent residue before use.

5.4 Level the instrument as indicated by the level indicator on the face of the instrument. Turn on the power and allow several seconds for the viscosity reading to stabilize and for trapped air in the rotor to escape.

5.5 Read the viscosity of the sample, from the correct scale, in Poises and record.

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