Building Materials (Concrete)

1.         Vibrators are used for
(a)        consolidation of concrete
(b)        compaction of concrete
(c)        segregating concrete
(d)        all of the above

2.         Immersion vibrators are also called
(a)        needle vibrators
(b)        form vibrators
(c)        surface vibrators
(d)        none of these

3.         A needle vibrator is specified by
(a)        dia. of needle
(b)        length of needle
(c)        frequency of vibrations
(d)        both (a) and (b)

4.         Curing of concrete is done for
(a)        promoting hydration of concrete
(b)        promoting hardening of concrete
(c)        both (a) and (b)
(d)        neither (a) nor (b)

5.         High temperature of concrete
(a)        reduces slump
(b)        increases water requirement
(c)        increases cement requirement
(d)        all these

6.         High temperature of concrete
(a)        increases hydration
(b)        causes poor gel formation
(c)        reduces strength and setting time
(d)        all these

7.         The temperature of concrete is maintained during hot weather conditions by cooling
(a)        coarse aggregate
(b)        sand
(c)        cement
(d)        water    (AMIE June99)

8.         Setting time can be retarded by using
(a)        sugar, 0.05% by weight of cement
(b)        lime
(c)        clay
(d)        none of these

9.         Concrete strength is mentioned on a specified age of
(a)        7 days
(b)        14 days
(c)        21 days
(d)        28 days

10.       At 7 days age of curing, a concrete cube gives comprehensive strength on testing, about____% of its 28 days strength.
(a)        80%
(b)        70%
(c)        50%
(d)        45%     (AMIE June97, IES 1995)


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