Concrete Technology (21-40)

Updated: Apr 8, 2020

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

higher initial setting time but lower final setting time

22. Modulus of rupture of concrete is a measure of flexural tensile strength

23. In order to obtain the best workability of concrete, the preferred shape of aggregate is rounded

24. The effect of adding calcium chloride in concrete is to increase shrinkage

to decrease setting time

25. Bulking of sand is maximum if moisture content is about 4%

26.Finer grinding of cement affects only the early development of strength

27. Poisson's ratio for concrete increases with richer mixes

28. 1% of voids in a concrete mix would reduce its strength by about 5%

29. The fineness modulus of fine aggregate is in the range of 2.0 to 3.5

30.The factor of safety for steel is lower than that for concrete

31. Examine the following statements Factor of safety for steel should be based on its yield stress,Factor of safety for concrete should be based on its ultimate stress

32. For a reinforced concrete section, the shape of shear stress diagram is parabolic above neutral axis and rectangular below neutral axis

33. Diagonal tension in a beam increases below the neutral axis and decreases above the neutral axis

34. If a beam fails in bond, then its bond strength can be increased most economically by using in inner bars but more in number

35.If nominal shear stress Tv exceeds the design shear strength of concrete Tc, the

nominal shear reinforcement as per IS : 456-1978 shall be provided for carrying a

shear stress equal to Tv = Tc

36. If the depth of actual neutral axis in a beam is more than the depth of critical

neutral axis, then the beam is called over-reinforced beam

37. If the depth of neutral axis for a singly reinforced rectangular section is re

presented by kd in working stress design, then the value of k for balanced section

depends on σst only

38. If the permissible stress in steel in tension is 140 N/mm2, then the depth of neutral axis for a singly reinforced rectangular balanced section will be 0.40 d

39. Modulus of elasticity of steel as per IS : 456-1978 shall be taken as 200kN/mm2

40.Minimum grade of concrete to be used in reinforced concrete as per IS:456-1978 is M15

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