Civil engineer objective questions – Design of Concrete Structure (Section-1)

1. The property of the ingredients to separate from each other while placing the concrete is called

a) Segregation

b) Compaction

c) Shrinkage

d) Bulking

2. Approximate value of shrinkage strain in concrete, is

a) 0.003

b) 0.0003

c) 0.00003

d) 0.03

3. Workability of concrete is directly proportional to

a) Aggregate cement ratio

b) Time of transit

c) Grading of the aggregate

d) All of above

4. The relation between modulus of rupture fcr, splitting fcs and direct tensile strength fcl is given by

a) tcr – rcs = tct

b) fcr > fcs > fc

c) fcr < fcs

d) fc5 > fcr > fc

5. Strength of concrete increasing with

a) Increase in water-cement ratio

b) Increase in fineness of cement

c) Decrease in curing time

d) Decrease in size of aggregate

6. As compared to ordinary Portland cement, use of pozzuolanic cement

a) Reduces workability

b) Increase bleeding

c) Increase shrinkage

d) Increase strength

7. According to IS : 456 – 1978, the modulus of elasticity of concrete Ec (in N/mm2) can be taken as

a) Ec = = 5700

b) Ec = = 570

c) Ec = = 5700 fck

d) Ec = where fck N/mm2 = 700 is the characteristic strength in

8. The mostly commonly used admixture which prolongs the setting and hardening time is

a) Gypsum

b) Calcium chloride

c) Sodium silicate

d) All of the above

9. The strength of concrete after one year as compared to 28 days strength is about

a) 10 to 15% more

b) 15 to 20% more

c) 20 to 25% more

d) 25 to 50% more

10. Admixtures which causes early setting, and hardening of concrete are called

a) Workability admixtures

b) Accelerators

c) Retarders

d) Air entraining agents

11. Increase in the moisture content in concrete

a) Reduces the strength

b) Increase the strength

c) Does not change the strength

d) All of the above

12. The relation between modulus of rupturefcr and characteristic strength of concrete fck is given by

a) fcr = 0.35Vf7

b) fcr = 0.57f7

c) fcr = 0.7Vf7

d) fcr = 1.2Vf7

13. The approximate value of the ratio between direct tensile strength and flexural strength is

a) 0.33

b) 0.5

c) 0.75

d) 1.0

14. Air entrainment in the concrete increase

a) Workability

b) Strength

c) The effect of temperature variations

d) The unit weight

15. Workability of concrete is inversely pro-portional to

a) Time of transit

b) ‘Vater-cement ratio

c) The air in the mix

d) Size of aggregate

16. The property of fresh concrete, in which the water in the mix tends to rise to the surface while placing and compacting is called

a) Segregation

b) Bleeding

c) Bulking

d) Creep

17. To determine the modulus of rupture, the size of test specimen used is

a) 150 * 150 * 500 mm

b) 100 * 100 * 700 mm

c) 150 * 150 * 700 mm

d) 100 * 100 * 500 mm

18. The percentage of voids in cement is approximately

a) 25%

b) 40%

c) 60%

d) 80%

19. Modulus of rupture of concrete is a measure of

a) Flexural tensile strength

b) Direct tensile strength

c) Compressive strength

d) Split tensile strength

20. In order to obtain the best workability of concrete, the preferred shaped of aggregate is

a) Rounded

b) Elongated

c) Angular

d) All of the above

21. As compared to ordinary Portland cement, high alumina cement has

a) Higher initial setting time but lower final setting time

b) Lower initial setting time but higher final setting time

c) Higher initial and final setting times

d) Lower initial and final setting times

22. Bulking of sand is maximum if moisture content is about

a) 2%

b) 4%

c) 6%

d) 10%

23. 1% of voids in a concrete mix would reduce its strength by about

a) 5%

b) 10%

c) 15%

d) 20%

24. Finger grinding of cement

a) Affects only the early development of strength

b) Affects only the ultimate strength

c) Both a and b

d) Does not affect the strength

25. Poisson’s ratio for concrete

a) Remains constant

b) Increase with richer mixes

c) Decrease with richer mixes

d) None of the above