Admixtures which cause early setting, and hardening of concrete are called_______________?
(A) workability admixtures
(B) accelerators
(C) retarders
(D) air entraining agents
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
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
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
As compared to ordinary portland cement, use of pozzuolanic cement_______________?
(A) reduces workability
(B) increases bleeding
(C) increases shrinkage
(D) increases strength
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
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
1% of voids in a concrete mix would reduce its strength by about______________?
(A) 5%
(B) 10 %
(C) 15%
(D) 20%
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