Pick up the correct statement from the following:
Water cement paste hardens due to hydration
During hardening cement binds the aggregates together
Cement provides strength, durability and water tightness to the concrete
All the above
Correct Answer :
D. All the above
Related Questions
Workability of concrete is directly proportional to
Aggregate cement ratio
Time of transit
Grading of the aggregate
All of above
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
The compressive strength of 100 mm cube as compared to 150 mm cube is always
Less
More
Equal
None of the above
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
According to ISI recommendations, the maximum depth of stress block for balanced section of a beam of effective depth d is
0.43 d
0.55 d
0.68 d
0.85 d
Hardening of cement occurs at
Rapid rate during the first few days and afterwards it continues to increase at a decreased rate
Slow rate during the first few days and afterwards it continues to increase at a rapid rate
Uniform rate throughout its age
None of these
For construction of structures in sea water, the cement generally preferred to, is
Portland-pozzolana cement
Quick setting cement
Low heat Portland cement
Rapid hardening cement
Curing
Reduces the shrinkage of concrete
Preserves the properties of concrete
Prevents the loss of water by evaporation
All of the above
Pick up the correct statement from the following:
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)
Pick up the correct statement from the following:
Continuous grading is not necessary for obtaining a minimum of air voids
The omission of a certain size of aggregate is shown by a straight horizontal line on the grading curve
The omission of a certain size of aggregate in concrete increases the workability but also increases the liability to segregation
All the above
If 20 kg of coarse aggregate is sieved through 80 mm, 40 mm, 20 mm, 10 mm, 4.75 mm, 2.36 mm, 1.18 mm, 600 micron, 300 micron and 150 micron standard sieves and the weights retained are 0 kg, 2 kg, 8 kg, 6 kg, 4 kg respectively, the fineness modulus of the aggregate, is
7.30
7.35
7.40
7.45
The lower water cement ratio in concrete, introduces
Smaller creep and shrinkage
Greater density and smaller permeability
Improved frost resistance
All the above
An aggregate which passes through 25 mm I.S. sieve and is retained on 20 mm sieve, is said to be flaky if its least dimension is less than
22.5 mm
18.5 mm
16.5 mm
13.5 mm
If the storey height is equal to length of RCC wall, the percentage increase in strength is
0
10
20
30
When shear stress exceeds the permissible limit in a slab, then it is reduced by
Increasing the depth
Providing shear reinforcement
Using high strength steel
Using thinner bars but more in number
If P, Y and Z are the weights of cement, fine aggregates and coarse aggregates respectively and W/C is the water cement ratio, the minimum quantity of water to be added to first batch, is obtained by the equation
0.1P + 0.3Y + 0.1Z = W/C × P
0.3P + 0.1Y + 0.01Z = W/C × P
0.4P + 0.2Y + 0.01Z = W/C × P
0.5P + 0.3Y + 0.01Z = W/C × P
The cement becomes useless if its absorbed moisture content exceeds
1 %
2 %
3 %
5 %
The critical section for finding maximum bending moment for footing under masonry wall is located
At the middle of the wall
At the edge of the wall
Halfway between the middle and edge of the wall
At a distance equal to effective depth of footing from the edge of the wall
Pick up the correct statement from the following:
Water enables chemical reaction to take place with cement
Water lubricates the mixture of gravel, sand and cement
Strength of concrete structure largely depends upon its workability
All the above
Modulus of elasticity of steel as per IS: 4561978 shall be taken as
20 kN/cm²
200 kN/cm²
200 kN/mm²
2 × 106 N/cm²
Maximum distance between expansion joints in structures as per IS: 456 1978 is
20 m
30 m
45 m
60 m
As compared to ordinary Portland cement, high alumina cement has
Higher initial setting time but lower final setting time
Lower initial setting time but higher final setting time
Higher initial and final setting times
Lower initial and final setting times
Select the incorrect statement
Lean mixes bleed more as compared to rich ones.
Bleeding can be minimized by adding pozzolana finer aggregate
Bleeding can be increased by addition 'of calcium chloride
None of the above
The increased cohesiveness of concrete, makes it
Less liable to segregation
More liable to segregation
More liable to bleeding
More liable for surface scaling in frosty weather
The 28 days cube strength of mass concrete using aggregates of maximum size 5 cm for gravity dams should be
Between 150 to 300 kg/cm2
Between 350 to 600 kg/cm2
Between 150 to 500 kg/cm2
Below 200 kg/cm2
Proper proportioning of concrete, ensures
Desired strength and workability
Desired durability
Water tightness of the structure
All the above
Which of the following has high tensile strength?
Plain hot rolled wires
Cold drawn wires
Heat treated rolled wires
All have same tensile strength
The permissible diagonal tensile stress in reinforced brick work is
About 0.1 N/mm²
Zero
0.3 N/mm² to 0.7 N/mm²
About 1.0 N/mm²
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
Addition of pozzolana to ordinary port land cement, causes
Decrease in early strength
Reduction in chemical action with sulphates
Increase in shrinkage
All the above