Cement and ConcreteCement and Concrete

HistoryHistoryCompositionCompositionTestingTestingKey TermsKey Terms

Key TermsKey TermsDesignation C 219-98Designation C 219-98

Air-entraining hydraulic cementAir-entraining hydraulic cement – hydraulic cement – hydraulic cement containing an air entraining addition in such amount as to cause containing an air entraining addition in such amount as to cause the product to entrain air in mortar within specified limits.the product to entrain air in mortar within specified limits.

Blast furnace slagBlast furnace slag – nonmetallic product consisting essentially – nonmetallic product consisting essentially of silicates and aluminosilicates of calcium and other bases that of silicates and aluminosilicates of calcium and other bases that is developed in a molten condition simultaneously with iron in a is developed in a molten condition simultaneously with iron in a blast furnace.blast furnace.

HydrationHydration – chemical reaction between hydraulic cement and – chemical reaction between hydraulic cement and water forming new compounds most of which have strength-water forming new compounds most of which have strength-producing properties. producing properties.

Hydraulic cementHydraulic cement – a cement that sets and hardens by – a cement that sets and hardens by chemical interaction with water and is capable of doing so under chemical interaction with water and is capable of doing so under water.water.

Portland cementPortland cement – a hydraulic cement produced by pulverizing – a hydraulic cement produced by pulverizing portland-cement clinker and usually containing calcium sulfate.portland-cement clinker and usually containing calcium sulfate.

ASTM Portland Cement TypesASTM Portland Cement TypesTypeType Characteristics and UseCharacteristics and Use

TYPE I, IA, STANDARDTYPE I, IA, STANDARD General Purpose, Most residential General Purpose, Most residential applicationsapplications

TYPE II, IIA, MODIFIEDTYPE II, IIA, MODIFIED Reduced heat of hydration, Reduced heat of hydration, increased sulfate resistanceincreased sulfate resistance

TYPE III, IIIA HIGH EARLY TYPE III, IIIA HIGH EARLY STRENGTHSTRENGTH

High strengths in one to three daysHigh strengths in one to three days

TYPE IV, LOW HEATTYPE IV, LOW HEAT Heat during hydration kept to a Heat during hydration kept to a minimum; intended for large minimum; intended for large masses, e.g., damsmasses, e.g., dams

TYPE V, SULFATE TYPE V, SULFATE RESISTANTRESISTANT

Especially good for marine Especially good for marine structures and soils with high alkalistructures and soils with high alkali

CementCement

A finely pulverized material A finely pulverized material consisting principally of compounds consisting principally of compounds of lime, silica, alumina, and iron.of lime, silica, alumina, and iron.

ConcreteConcrete

A monolithic, ceramic product of A monolithic, ceramic product of aggregates bonded with cement, such as aggregates bonded with cement, such as Portland or asphalt.Portland or asphalt.

Composition of ConcreteComposition of Concrete

Air-entrained Air-entrained Non-air-entrainedNon-air-entrained

CementCement 15%15% 15%15%

Water Water 18%18% 21%21%

Air Air 8% 8% 3% 3%

Fine Aggregate Fine Aggregate 28%28% 30%30%

Course Aggregate Course Aggregate 31%31% 31%31%

Note: All values are approximateNote: All values are approximate

Fine and Course AggregatesFine and Course Aggregates

Fine aggregates – stone or sand that can Fine aggregates – stone or sand that can pass through a sieve with ¼” square holes.pass through a sieve with ¼” square holes.

Course Aggregate – rock or stone greater Course Aggregate – rock or stone greater than ¼” . Usually not larger than 1 ½” than ¼” . Usually not larger than 1 ½”

HistoryHistory

Roman Empire – Colosseum and other structures Roman Empire – Colosseum and other structures made with a type of cement made from slaked made with a type of cement made from slaked lime and lime and pozzolona pozzolona (volcanic ash from Mt. (volcanic ash from Mt. Vesuvius) First Vesuvius) First Hydraulic Cement.Hydraulic Cement.

1756 John Smeaton – discovers that cement made 1756 John Smeaton – discovers that cement made from limestone with a substantial volume of clay from limestone with a substantial volume of clay hardens under water.hardens under water.

1824 Joseph Aspdin – invents 1824 Joseph Aspdin – invents Portland CementPortland Cement

HydrationHydration

The chemical reaction between hydraulic The chemical reaction between hydraulic cement and water forming new compounds cement and water forming new compounds most of which have strength –producing most of which have strength –producing properties.properties.

Composition of ConcreteComposition of Concrete

11% Cement (usually Portland)11% Cement (usually Portland) 16% Water16% Water 6% Air6% Air 26% Sand26% Sand 41% Gravel or Crushed Stone41% Gravel or Crushed Stone

Fiber Reinforced ConcreteFiber Reinforced Concrete

Low Fiber volume composite: Low Fiber volume composite: concrete contains concrete contains less than 1% fiber. It is used for field applications less than 1% fiber. It is used for field applications involving large volumes of concrete. The fibers involving large volumes of concrete. The fibers do not significantly increase the strength of the do not significantly increase the strength of the concrete. Low fiber volume concrete is used for concrete. Low fiber volume concrete is used for paving roads.paving roads.

High Fiber Volume Concrete: High Fiber Volume Concrete: Typically used for Typically used for thin sheets with cement mortar mix. The fiber thin sheets with cement mortar mix. The fiber volume in this mix ranges from 5% to 15%.volume in this mix ranges from 5% to 15%.

Fiber Reinforced ConcreteFiber Reinforced Concrete

High Fiber Volume CompositeHigh Fiber Volume Composite: : The fiber The fiber volume in this mix can be as high as 40%. This volume in this mix can be as high as 40%. This significantly increases the strength and toughness significantly increases the strength and toughness

of the mixof the mix. The reinforcement in . The reinforcement in High Fiber High Fiber Volume Composite concrete is usually in sheet Volume Composite concrete is usually in sheet form. This reinforced concrete type is used in roof form. This reinforced concrete type is used in roof and wall panels.and wall panels.

Standardized Tests of ConcreteStandardized Tests of Concrete

ASTM C-143 Slump TestASTM C-143 Slump Test ASTM C-39 Compressive Strength TestASTM C-39 Compressive Strength Test ASTM C-78ASTM C-78 Flexural Strength TestFlexural Strength Test

ASTM C-39 Standard Test Method Compressive ASTM C-39 Standard Test Method Compressive Strength of Cylindrical Concrete SpecimensStrength of Cylindrical Concrete Specimens

ProcedureProcedure

7.3 All test specimens for a given test age shall be broken 7.3 All test specimens for a given test age shall be broken within the permissable time tolerances prescribed as within the permissable time tolerances prescribed as follows:follows:

Test AgeTest Age Permissible TolerancePermissible Tolerance

24 hours24 hours +/- .5 h or 2.1%+/- .5 h or 2.1%

3 days3 days 2 h or 2.8%2 h or 2.8%

7 days7 days 6 h or 3.6%6 h or 3.6%

28 days28 days 20h or 3.0%20h or 3.0%

90 days90 days 2 days or 2.2%2 days or 2.2%

ASTM C-39 Standard Test Method Compressive ASTM C-39 Standard Test Method Compressive Strength of Cylindrical Concrete SpecimensStrength of Cylindrical Concrete Specimens

ProcedureProcedure

8.1 If the specimen length to diameter ratio is less than 1.8, 8.1 If the specimen length to diameter ratio is less than 1.8, correct the result obtained in 8.1 by multiplying by the correct the result obtained in 8.1 by multiplying by the appropriate correction factor in the following table:appropriate correction factor in the following table:

L/DL/D 1.751.75 1.5 1.5 1.25 1.25 1.001.00

Factor:Factor: 0.980.98 0.96 0.96 0.93 0.93 0.870.87

Test CylindersTest Cylinders

TABLE 11.2CONCRETE MIXES FOR SELECTED APPLICATIONS

APPLICATION CEMENT CONTENT BAGS/YD

MAX SIZE AGGREGATE

WATER/ CEMENT RATIO GALS/SACK

28TH DAY COMPRESSIVE STRENGTH

8" Basement Wall

5.0 1 - 1 1/2 " 7 2800 

4" Basement Wall 

6.2 1" 6 3500

Stairs 6.2 1" 6 3500 

Driveways, Porches

6.2 1" 6 3500

Table 11.3ASTM Time Tolerances For Concrete Compressive Strength Test

TEST AGE PERMISSABLE TOLERANCE

 

24 Hours ±0.5 h OR 2.1%

3 Days 2 h OR 2.8%

7 Days 6 h OR 3.6%

28 Days 20 h OR 3.0%

90 Days 2 days OR 2.2%