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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