Workability improved by adding
Air-entraining agent
Foaming agent
Oily-agent
All the above
Correct Answer :
D. All the above
Related Questions
Expansion joints are provided if the length of concrete structures exceeds
10 m
15 m
15 m
45 m
Bulking of sand is
Mixing of different sizes of sand particles
Mixing of lime with sand
Maximum water with sand
Swelling of sand when wetted
Vicat apparatus is used for
Fineness test
Consistency test
Test for setting time
Test for tensile strength
Minimum grade of concrete to be used in reinforced concrete as per IS: 4561978 is
M 15
M 20
M 10
M 25
Examine the following statements: (i) Factor of safety for steel should be based on its yield stress, (ii) Factor of safety for steel should be based on its ultimate stress, (iii) Factor of safety for concrete should be based on its yield stress, (iv) Factor of safety for concrete should be based on its ultimate stress. The correct statements are
(i) and (iii)
(i) and (iv)
(ii) and (iii)
(ii) and (iv)
In the design of a front counterfort in a counterfort retaining wall, the main reinforcement is provided on (i) Bottom face near counterfort (ii) Top face near counterfort (iii) Bottom face near centre of span (iv) Top face near centre of span The correct answer is
Only (i)
Only (ii)
Both (i) and (iv)
Both (ii) and (iii)
A higher modular ratio shows
Higher compressive strength of concrete
Lower compressive strength of concrete
Higher tensile strength of steel
Lower tensile strength of steel
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
The light weight aggregates are obtained from
Sedimentary rocks
Metamorphic rocks
Igneous rocks
Volcanic source
For walls, columns and vertical faces of all structural members, the form work is generally removed after
24 to 48 hours
3 days
7 days
14 days
Pick up the correct statement from the following:
Lime in excess, causes the cement to expand and disintegrate
Silica in excess, causes the cement to set slowly
Alumina in excess, reduces the strength of the cement
All the above
Water required per bag of cement, is
7 kg
14 kg
21 kg
35 kg
Specified compressive strength of concrete is obtained from cube tests at the end of
3 days
7 days
21 days
28 days
The factor which affects workability, is
Water content and its temperature
Shape and size of the aggregates
Air entraining agents
All the above
Construction joints are generally provided in concrete
Roads
Retaining walls
Lining of canals
All the above
Pick up the incorrect statement from the following. For performing compressive strength test of cement
Cement and standard sand mortar are used in the ratio of 1 : 3
Water is added at the rate of (P/4) + 3.0 percentage of water where P is the percentage of water for standard consistency
A cube mould of 10 cm × 10 cm × 10 cm is used
The prepared moulds are kept in a atmosphere of 50% relative humidity
An aggregate is said to be flaky if its least dimension is less than
1/5th of mean dimension
2/5th of mean dimension
3/5th of mean dimension
4/5th of mean dimension
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
The mixture of different ingredients of cement, is burnt at
1000°C
1200°C
1400°C
1600°C
Inert material of a cement concrete mix, is
Water
Cement
Aggregate
None of these
Percentage of pozzolanic material containing clay upto 80% used for the manufacture of pozzolana cement, is
30 %
40 %
50 %
60 %
Pozzolana cement is used with confidence for construction of
Dams
Massive foundations
R.C.C. structures
All the above
An aggregate is known as cyclopean aggregate if its size is more than
4.75 mm
30 mm
60 mm
75 mm
The ratio of the length to breadth of a wooden float, is
4.5
5.5
6.5
7.5
High temperature
Increases the strength of concrete
Decreases the strength of concrete
Has no effect on the strength of concrete
None of these
Concrete is unsuitable for compaction by a vibrator if it is
Dry
Earth moist
Semi-plastic
Plastic
Transport of concrete by pumps, is done for a distance of
100 m
200 m
300 m
400 m
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
Modulus of rupture of concrete is a measure of
Flexural tensile strength
Direct tensile strength
Compressive strength
Split tensile strength
If the permissible stress in steel in tension is 140 N/mm², then the depth of neutral axis for a singly reinforced rectangular balanced section will be
0.35 d
0.40 d
0.45 d
Dependent on grade of concrete also