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Quality Control Quality Control TestingTesting
Mississippi Concrete Mississippi Concrete Industries AssociationIndustries Association
Robert Varner, P.E.Robert Varner, P.E.
Testing Freshly Mixed Testing Freshly Mixed ConcreteConcrete
Sampling - ASTM C172Sampling - ASTM C172 Slump - ASTM C143Slump - ASTM C143 Temperature - ASTM C1064Temperature - ASTM C1064 Density - ASTM C138Density - ASTM C138 Air Content - ASTM C231/C173Air Content - ASTM C231/C173 Strength Specimens - ASTM Strength Specimens - ASTM
C31C31
Sampling - ASTM C 172Sampling - ASTM C 172
1 ft1 ft33 Composite Composite
samplesample Middle of truckMiddle of truck Protect sampleProtect sample
Slump - ASTM C143Slump - ASTM C143
Consistency: The Consistency: The ability of freshly ability of freshly mixed concrete mixed concrete to flow as to flow as measured in the measured in the slump test. slump test. (expressed in (expressed in inches of slump)inches of slump)
Temperature ASTM C1064Temperature ASTM C1064
• Affects concrete behavior• May be important in trouble-shooting
problems• May be a specification issue
Density - ASTM C138 Density - ASTM C138 Density (Unit Density (Unit
Weight)Weight)– Weight of concrete Weight of concrete
divided by a known divided by a known volume.volume.
– Conventional Conventional concrete has a unit concrete has a unit weight in the range weight in the range of 137 to 150 pcfof 137 to 150 pcf
Lightweight: 15 pcfLightweight: 15 pcf Heavyweight: 375 pcfHeavyweight: 375 pcf
– Measured primarily Measured primarily to compute yieldto compute yield
Yield Yield
Yield is the volume of concrete produced Yield is the volume of concrete produced in a batch (typically expressed in yd in a batch (typically expressed in yd 33))
yield =yield = Batch weights Batch weights
(Cement,FA,CA,H(Cement,FA,CA,H22O) O) Unit Unit WeightWeight
Air Content Air Content ASTM C 173 - ASTM ASTM C 173 - ASTM C231C231
Measures entrained (tiny) and Measures entrained (tiny) and entrapped (larger) air voids, expressed entrapped (larger) air voids, expressed as a percentage of the total volume of as a percentage of the total volume of concreteconcrete
Entrained: generally 0.0004” to 0.04” ØEntrained: generally 0.0004” to 0.04” Ø Entrapped: 0.04” Ø and upEntrapped: 0.04” Ø and up Somewhat a function of aggregate Somewhat a function of aggregate
characteristicscharacteristics– Non-air-entrained concrete w/ 1” coarse Non-air-entrained concrete w/ 1” coarse
aggregate has about 1-1/2% entrapped airaggregate has about 1-1/2% entrapped air
Volumetric Method Volumetric Method ASTM C173ASTM C173
Pressure Method ASTM C231Pressure Method ASTM C231
Strength SpecimensStrength Specimens
CylindersCylinders– 6 X 126 X 12– 4 X 84 X 8
BeamsBeams– 6 X 6 X 206 X 6 X 20
Curing SpecimensCuring Specimens– Standard curing Standard curing – Field curingField curing
Making & Curing Concrete Test
Specimens
ASTM C31 Field
ASTM C192 Lab
Compressive Strength of Cylindrical Specimens
ASTM C39
ASTM C 78Flexural Strength - Third Point Loading
Making & Curing Concrete
Test Specimens
ASTM C31 Field
ASTM C192 Lab
Standard CuringStandard Curing Curing procedures required by Curing procedures required by
ASTM C 31 for strength specimens ASTM C 31 for strength specimens that are made for:that are made for:– Acceptance testingAcceptance testing– Checking adequacy of mix proportions Checking adequacy of mix proportions – Quality controlQuality control
Includes 2 curing stages:Includes 2 curing stages:– Initial curingInitial curing– Final curingFinal curing
Initial CuringInitial Curing
TemperatureTemperature– < 6000 psi – 60 to < 6000 psi – 60 to
80 80 ° F° F– ≥ ≥ 6000 psi – 68 to 6000 psi – 68 to
78 ° F78 ° F MoistureMoisture
– Prevent moisture Prevent moisture lossloss
Time Time – Up to 48 hoursUp to 48 hours
Transportation of Transportation of Cylinders To Cylinders To LaboratoryLaboratory
Wait 8 hours after final setWait 8 hours after final set Protect with suitable cushioning materialProtect with suitable cushioning material Protect from freezingProtect from freezing Prevent moisture lossPrevent moisture loss Transportation time not to exceed 4 hoursTransportation time not to exceed 4 hours
Final CuringFinal Curing
TemperatureTemperature– 73° ± 3° F73° ± 3° F
MoistureMoisture– Free moisture on Free moisture on
surface at all timessurface at all times TimeTime
– Within 30 minutes Within 30 minutes after removing the after removing the molds until testingmolds until testing
Field CuringField Curing
Temperature and moisture conditions as Temperature and moisture conditions as close as possible to those of the in-place close as possible to those of the in-place concrete for curing specimens that are concrete for curing specimens that are made for:made for:
– Strength verification prior to putting the Strength verification prior to putting the structure or pavement into servicestructure or pavement into service
– Comparison with test results of standard cured Comparison with test results of standard cured specimens or various in-place test methodsspecimens or various in-place test methods
– Adequacy of curing and protection of concrete Adequacy of curing and protection of concrete in the structurein the structure
– Strength check for form or shoring removalStrength check for form or shoring removal
Questions?Questions?Mississippi Concrete Industries Mississippi Concrete Industries AssociationAssociation
Phone: (601) 957-5274Phone: (601) 957-5274
email: email: [email protected]@mississippiconcrete.com
website: mississippiconcrete.comwebsite: mississippiconcrete.com
