1. Strength of concrete is ___________
a) \(f_{ck} = K(\frac{c}{C+W+A})^2\)
b) \(f_{ck} = K(\frac{C+A}{C+W+A})^2\)
c) \(f_{ck} = K(\frac{C+W}{C+W+A})^2\)
d) \(f_{ck} = K(\frac{C+W+A}{C+W+A})^2\)
Explanation: It is the formula to find the Strength of concrete when we have the volume of cement, aggregates and water.
2. As per & 5456:200 Young’s modulus of concrete is _______________
a) 1000 fck
b) 5000 fck2
c) 5700 fck
d) 150 fck
Explanation: 5000 fck2 is the formula of young’s modulus of the concrete according to IS 5456:200.
3. Strength of concrete is proportional to ______________
a) Sand content
b) Water cement ratio
c) Aggregate ratio
d) Cement water ratio
Explanation: Strength of concrete is proportional to Cement water ratio and inversely proportional to w/c ratio.
4. Strength of concrete increase with _____________
a) Increase with w/c ratio
b) Decrease with w/c ratio
c) Decrease in size of aggregates
d) Decrease in curing time
Explanation: As mentioned above that Strength of concrete is inversely proportional to w/c ratio.
5. Strength of concrete increase with _________
a) Increase with w/c ratio
b) Increase in fineness of cement
c) Decrease in size of aggregates
d) Decrease in curing time
Explanation: Strength of concrete increase with increase in fineness of the cement.
6. Approximate ratio of the strength of the cement conc of 7 days to that of 28 days (2/3)?
a) .75
b) .85
c) 1
d) 1.15
Explanation: After the lab broke the seven-day cylinders, the cylinder from the pier with added water broke at 1980 psi. The other seven-day cylinders were as high as 2620 psi.
7. Approximate ratio of strength of the 30 cm cube to that of 15 cm cube is _____________
a) 1.1
b) 1
c) .9
d) .75
Explanation: The strength of cylinder with diameter of 15cm and 30cm tall can be approximated as 0.84 of the strength of a 15x15x15 cm cube according to Eurocodes.
8. Approximate ratio of direct tensile strength to flexural strength is ____________
a) .25
b) .33
c) .5
d) .05
Explanation: Approximate ratio of direct tensile strength to flexural strength is .5 according to the formula.
9. The addition of a pozzolanic admixture such as fly ash reduces the ____________
a) C3S
b) C3A
c) C2S
d) C4AF
Explanation: The addition of a pozzolanic admixture such as fly ash reduces the C3A content of cement.
10. Lowering of ____________ might also help, since this would reduce the amount of CH that forms.
a) C3S
b) C3A
c) C2S
d) C4AF
Explanation: Lowering of C3S might also help, since this would reduce the amount of CH that forms.