Segregation is responsible for
Honey-combed concrete
Porous layers in concrete
Surface scaling in concrete
All the above
Correct Answer :
D. All the above
Related Questions
To prevent segregation, the maximum height for placing concrete, is
100 cm
125 cm
150 cm
200 cm
Pick up the correct statement from the following:
A highly absorptive aggregate reduces the workability of concrete considerably
The specific gravity of aggregate is important for the determination of the moisture content
The absorption and porosity of an aggregate influence the property of the concrete
All the above
Pick up the correct statement from the following:
Bulking of sand is caused due to formation of a thin film of surface moisture
Fine sand bulks more than coarse sand
The volume of fully saturated sand, is equal to the volume of dry and loose sand
All the above
Poisson's ratio for concrete
Remains constant
Increases with richer mixes
Decreases with richer mixes
None of the above
Workability of concrete is directly proportional to
Aggregate cement ratio
Time of transit
Grading of the aggregate
All of above
The property of the ingredients to separate from each other while placing the concrete is called
Segregation
Compaction
Shrinkage
Bulking
A concrete using an air entrained cement
Has strength less than 10% to 15%
Has more resistance to weathering
Is more plastic and workable
Is free from segregation and bleeding
If the average compressive strength is 4000 kg/cm2 and standard deviation is 500, the co-efficient of variation is
10 %
12.5 %
15 %
18.5 %
1% of voids in a concrete mix would reduce its strength by about
5 %
10 %
15 %
20 %
I.S. Sieve Nos. 10 mm and 4.75 mm are generally used for grading of
Coarse aggregates
Fine aggregates
Neither (a) nor (b)
Both (a) and (b)
The mixture of different ingredients of cement, is burnt at
1000°C
1200°C
1400°C
1600°C
Air entrainment in the concrete increases
Workability
Strength
The effects of temperature variations
The unit weight
The concrete mix which causes difficulty in obtaining a smooth finish, possess
Segregation
Internal friction
Hardness
Bleeding
Di-calcium silicate (C2S)
Hydrates rapidly
Generates less heat of hydration
Hardens rapidly
Provides less ultimate strength to cement
Workability of concrete is inversely proportional to
Time of transit
Water-cement ratio
The air in the mix
Size of aggregate
Segregation is responsible for
Honey-combed concrete
Porous layers in concrete
Surface scaling in concrete
All the above
For a cantilever of effective depth of 0.5 m, the maximum span to satisfy vertical deflection limit is
3.5 m
4 m
4.5 m
5 m
For the construction of the retaining structures, the type of concrete mix to be used, is
1 : 3 : 6
1 : 2 : 4
1 : 1 ½ : 3
1 : 4 : 8
The process of mixing, transporting, placing and compacting concrete using Ordinary Port land Cement should not take more than
30 minutes
40 minutes
60 minutes
90 minutes
Pick up the correct statement from the following:
The concrete gains strength due to hydration of cement
The concrete does not set at freezing point
The strength of concrete increases with its age
All the above
Expansion joints are provided if the length of concrete structures exceeds
10 m
15 m
15 m
45 m
The minimum cover in a slab should neither be less than the diameter of bar nor less than
10 mm
15 mm
25 mm
13 mm
Ratio of permissible stress in direct compression and bending compression is
Less than 1
Between 1 and 1.5
Between 1.5 and 2.0
Greater than 2
Pick up the incorrect statement from the following:
The degree of grinding of cement, is called fineness
The process of changing cement paste into hard mass, is known as setting of cement
The phenomenon by virtue of which cement does not allow transmission of sound, is known as soundness of cement
The heat generated during chemical reaction of cement with water, is known as heat of hydration
For a reinforced concrete section, the shape of shear stress diagram is
Wholly parabolic
Wholly rectangular
Parabolic above neutral axis and rectangular below neutral axis
Rectangular above neutral axis and parabolic below neutral axis
Cube strength of controlled concrete to be used for pre-tensioned and post-tensioned work respectively should not be less than
35 MPa and 42 MPa
42 MPa and 35 MPa
42 MPa and 53 MPa
53 MPa and 42 MPa
Pick up the correct statement from the following:
Segregation is necessary for a workable concrete
Consistency does not affect the workability of concrete
If the concrete mix is dry, the slump is maximum
None of these
The percentage of reinforcement in case of slabs, when high strength deformed bars are used is not less than
0.15
0.12
0.30
1.00
The average permissible stress in bond for plain bars in tension is
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
The condition not applicable to water cement ratio law, is
Internal moisture conditions on hydration continue till complete strength is gained
Concrete specimens may be tested at any temperature
Concrete specimens need be of same age
Concrete specimens need be of same size