1.5
2.0
2.5
3.0
B. 2.0
1 %
2 %
3 %
5 %
2.5 cm
5.0 cm
7.5 cm
10 cm
Weakness of concrete
Excessive laitance
Segregation
All the above
Is maximum at neutral axis
Decreases below the neutral axis and increases above the neutral axis
Increases below the neutral axis and decreases above the neutral axis
Remains same
Ordinary Portland cement
Rapid hardening cement
Low heat cement
Blast furnace slag cement
Increased by 10% for bars in compression
Increased by 25% for bars in compression
Decreased by 10% for bars in compression
Decreased by 25% for bars in compression
Fineness test
Consistency test
Setting time test
Soundness test
Construction joints are necessarily planned for their locations
Expansion joints are provided to accommodate thermal expansion
Construction joints are provided to control shrinkage cracks
All the above
Very fine sand
Fine sand
Medium sand
Coarse sand
A rich mix of concrete possesses higher strength than that a lean mix of desired workability with excessive quantity of water
The strength of concrete decreases as the water cement ratio increases
Good compaction by mechanical vibrations, increases the strength of concrete
None of these
0.37 fy
0.57 fy
0.67 fy
0.87 fy
Segregation
Compaction
Shrinkage
Bulking
Sedimentary rocks
Metamorphic rocks
Igneous rocks
Volcanic source
1 : 3 : 6 mix
1 : 1 :2 mix
1 : 2 : 4 mix
1 : 1.5 : 3 mix
(i) and (iii)
(i) and (iv)
(ii) and (iii)
(ii) and (iv)
1/4
1/5
1/6
1/8
Less liable to segregation
More liable to segregation
More liable to bleeding
More liable for surface scaling in frosty weather
10 %
12 %
15 %
25 %
Reduces the shrinkage of concrete
Preserves the properties of concrete
Prevents the loss of water by evaporation
All of the above
Aggregates should be hard and durable
Water should be free from organic materials
Cement should be sufficient to produce the required strength
All the above
2/3 mean dimension
3/4 mean dimension
3/5 mean dimension
5/8 mean dimension
Less than 12
Less than 18
Between 18 and 24
More than 24
Clay
Sand
Gravel
None of these
20.5 mm
30.5 mm
40.5 mm
50.5 mm
0.43 d
0.55 d
0.68 d
0.85 d
The free water is the amount of water added while mixing and the amount of water held on the surface of the aggregates prior to mixing
The total water is the free water and the amount actually absorbed by the aggregates
Neither (a) nor (b)
Both (a) and (b)
Membrane method
Ponding method
Covering surface with bags
Sprinkling water method
Workability
Strength
The effects of temperature variations
The unit weight
Hydrates rapidly
Generates less heat of hydration
Hardens rapidly
Provides less ultimate strength to cement
Less than 1
Between 1 and 1.5
Between 1.5 and 2.0
Greater than 2