2. Compression Test
ASTM C39: cylindrical specimen (6 in. by 12 in.)
For normal-weight concrete: fc’ range is 21 MPa to 34
MPa (3000 psi to 5000 psi)
Compressive strength depends on specimen size
Larger specimens = greater probability for weaker
elements, reducing strength
Larger specimens have less variability and better
representation of actual concrete
3.
4. Split tension test
Measures the tensile strength on concrete (ASTM C496)
Cylinder is subjected to compressive load along vertical
diameter at a constant rate until fatigue
Failure occurs along vertical diameter due to tension
developed in transverse direction
Split tension is computed by T = 2p/BLD
T = tensile strength, MPa (psi)
p= load at failure, N (psi)
L = length of specimen, mm (in.)
D = diameter of specimen, mm (in.)
Tensile strength varies from 2.5 MPa to 31 MPa (360 psi to
450 psi), about 10% of compressive strength
5.
6. Flexure strength test
Used for measuring Modulus of Rupture (MR)
Important test for road and airport concrete pavements
Beam specimen of square x-section is loaded into a 3-point loading apparatus·
Calculation of MR
If the fracture occurs in the middle 1/3 of the span
R = PL/(bd^2)
Where:
R = flexure strength, MPa (psi)
P = maximum load applied, N (lb)
L = span length, mm (in.)
b = average width of specimen, mm (in.)
a = average depth of specimen, mm (in.)
If fracture occurs further outside the middle third, the results must be thrown
out