391. The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by_______________?
A. tcr – rcs = tct
B. fcr>fcs>fc
C. fcr<fcs
D. fc5>fcr>fC

392. Strength of concrete increases with________________?
A. increase in water-cement ratio
B. increase in fineness of cement
C. decrease in curing time
D. decrease in size of aggregate

393. As compared to ordinary Portland cement, use of pozzuolanic cement_______________?
A. reduces workability
B. increases bleeding
C. increases shrinkage
D. increases strength

394. 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 = = 5700fck
D. Ec = where fck N/mm2 = 700 is the characteristic strength in

395. The most commonly used admixture which prolongs the setting and hardening time is_______________?
A. gypsum
B. calcium chloride
C. sodium silicate
D. all of the above

396. 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

397. Admixtures which cause early setting, and hardening of concrete are called_______________?
A. workability admixtures
B. accelerators
C. retarders
D. air entraining agents

398. Increase in the moisture content in concrete_________________?
A. reduces the strength
B. increases the strength
C. does not change the strength
D. all of the above

399. The relation between modulus of rupture fcr 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
where fcr and fck are in N/mm2′

400. 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

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