64. Water cement ratio is
A. volume of water to that of cement
B. weight of water to that of cement
C. weight of concrete to that of water
D. both A and B of the above
65. Water cement ratio is generally expressed in volume of water required per
A. 10 kg
B. 20 kg
C. 30 kg
D. 50 kg
66. Pick up the incorrect statement from the following :
A. A rich mix of concrete possesses higher strength than that a lean mix of desired workability with excessive ?quantity of water
B. The strength of concrete decreases as the water cement ratio increases
C. If the water cement ratio is less than 045, the concrete is not workable and causes honey-combed structure
D. Good compaction by mechanical vibrtions, increases the strength of concrete
67. According to Water-Cement Ratio Law, the strength of workable plastic concrete
A. depends upon the amount of water used in the mix
B. does not depend upon the quality of cement mixed with aggregates
C. does not depend upon the quanity of cement mixed with aggregates
D. all the above
68. The condition not applicable to water cement ratio law, is
A. internal moisture conditions on hydration continue till complete strength is gained
B. concrete specimens may be tested at any temperature
C. concrete specimens need be of same age
D. concrete specimens need be of same size
69. Pick up the correct statement from the following :
A. The concrete gains strength due to hydration of cement
B. The concrete cured at a temperature below 23?C, gains strength up to 28 days
C. The concrete does not set at freezing point
D. All the above
70. The datum temperature for maturity by Plowman, is
A. 23?C
B. 0?
C.( c) - 56?C
D.117?C
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