Basic Concrete Tests

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Basic Tests

Cylinder CompressionSplit Tension

Beam FlexureElastic Modulus

SlumpAir Content

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Concrete Strength

unconfined compressioncylindrical specimen

6" diameter12" height

35 7 psi/s loadingcured 28-days

95% relative humidity

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Shape Effects

Shape Effects

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Slenderness Effects

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Size Effects

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Loading Rate Effects

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Splitting Tension Test

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Splitting Tension Test

2t

PfLD

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Splitting Tension Test

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Beam Flexure Test

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Beam Flexure Test

3L

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Beam Flexure Test

2

PLMORbd

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Beam Flexure Test

2

PLMORbd

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Elastic Modulus

1

E

1

E

failure

cf

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Elastic Modulus

1

E

2,0.4 cf

10.00005,

1

2

0.40.00005

cfE

cf

1

E

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Elastic Modulus

1

E

0.0007,2320

0.00005,250

62320 250 3.2 10 psi

0.0007 0.00005E

5800cf

1

E

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Compressometer

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Compressometer

L = ½ HH

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Compressometer

L−2

Pivot rodL−

d/2 d/2

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Slump Test

Fill the cone inthe prescribed

manner

Raise the cone, invert it,and measure slump to

the center of the sample

Strike offthe excess

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Slump Types

“True” slump

Good cohesionGood consistency

Collapse Slump

Too lean or too wetMay be harsh

Shear Slump

Lacks cohesionMay segregate

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Methods for Determining Air Content

gravimetric method (ASTM C-138)

volumetric method (ASTM C-173)

pressure method (ASTM C-231)

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Gravimetric Method

actual

no air

air content 1 100%

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Air-Free Unit Weight

water cement gravel sand

no airwater cement gravel sand

W W W WV V V V

ingredientingredient

bulk w

WV

G

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Example

Wwater = 320 lb

Wcement = 580 lb

Wgravel = 1940 lb

Wsand = 1110 lb

Gwater = 1.00

Gcement = 3.15

Ggravel = 2.68

Gsand = 2.65

3

no air 3

320 580 1940 1110 lb 149.7 lb ft5.13 2.95 11.60 6.71 ft

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Example (cont.)

Assume

actual = 146.2 lb/ft3

146.2air content 1 100% 2.3%149.7

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Volumetric Method

The measuring bowl is filled with concrete, the device is assembled, and water is added to reach the zero mark in the neck. As the device is agitated, the air in the concrete is replaced by water from the neck and the water level drops in proportion to the air content.

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Pressure Method

The bowl is filled with concrete, the device is assembled, and water is added to reach the zero mark in the neck. As the unit is pressurized, the air bubbles compress, the concrete surface falls and the water level drops in proportion to the change in air volume.