Concrete Technology (201-220)

Updated: Apr 30, 2020

201. Steam curing is not recommended for use with high alumina cement


202. According to IS : 456-1978, minimum period stipulated for moist curing of

concrete using ordinary portland cement is 7 days




203. Curing period required is minimum for the concrete using rapid hardening cement


204. For reinforced concrete exposed to sulphate attack minimum grade required is M 20


205. According to IS : 456-1978, the total sulphate content as percentage of mass of cement in concrete mix should be limited 4

206. According to IS : 456-1978, the total chloride content as percentage of mass of

cement in concrete mix should be limited 0.16


207. According to IS : 456-1978, the maximum water-cement ratio in plain concrete to ensure durability in mild exposure is limited to 0.70

208. To ensure durability for similar conditions of exposure, water-cement ratio in

reinforced concrete as compared to that in plain concrete is less

209. For a given degree of hydration, the effect of increasing water-cement ratio in

concrete is to increase permeability

210. For a given water-cement ratio in concrete, with passage of time, the permeability decreases

211. As compared to moist-cured concrete, the permeability of steam-cured concrete is more

212. If compressive strength of concrete determined from 150mm x 300mm

cylinders is x, then the compressive 1.25 x

213. The compressive strength of concrete determined from 150 mm x 150 mm cylinders as compared to that determined from 150 mm x 300 mm cylinders is

more

214. The compressive strength of concrete determined from 150 mm x l50 mm

cylinders as compared to that determined from 150 mm cubes is more

215.Assertion A : For determining uniaxial compressive strength of concrete, cube is a better test specimen as compared to cylinder.

Reason R : Stress distribution is more uniform over the cross-section of a

cylinder as compared to cube. Select your answer based on the coding system given below A is false but R is true.

216. According to IS : 456-1978, if fy is the characteristic strength of steel and Es is

the modulus of elasticity of steel, then the maximum strain in the tension

reinforcement in the section at failure should not be less than


217. Design strength of concrete for limit state of collapse is taken as

where fck is the characteristic coropressive strength of concrete and r is partial safetyfactor for concrete.

0.67 fck/r


218.In limit state design of concrete for flexure, the area of stress block is taken as



where fck is characteristic compressive strength of concrete and xu is depth of

neutral axis

219.Shape of idealized stress-strain curve for concrete as prescribed by IS : 456-1978 is rectangular-paraboiic


220. In limit state design, under-reinforced section is one in which

tensile strain in steel reaches yield value while maximum compressive

strain in concrete is less than its ultimate crushing strain

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