Concrete Technology (1-20)

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

150 x150 x700 mm

2.The property of fresh concrete, in which the water in the mix tends to rise to the

surface while placing and compacting, is called bleeding

3. Lean mixes bleed less as compared to rich ones,

4.The property of fresh concrete, in which the water in the mix tends to rise to the

surface while placing and compacting, is called segregation

5. Workability of concrete is directly proportional to grading of the aggregate

6. Workability of concrete is inversely proportional to time of transit

7.Approximate value of shrinkage strain in concrete, is 0.0003

8.Air entrapment in the concrete increases workability

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

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

strength is 0.5

11.Strength of concrete increases with increase in fineness of cement

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

13.The compressive strength of 100 mm cube as compared to 150 mm cube is always more

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

15.Increase in the moisture content in concrete reduces the strength

16.As compared to ordinary portland cement, use of pozzuolanic cement

increases shrinkage

17.Admixtures which cause early setting, and hardening of concrete are called

accelerators

18.The most commonly used admixture which prolongs the setting and hardening time is gypsum

19.The percentage of voids in cement is approximately 40%

20.The strength of concrete after one year as compared to 28 days strength is about 20 to 25% more