Civil Engineer must know these Questions & Answer
In This article i am telling you those topics are mainly asked in interviews if you have 2-3 year Experience
1. Why sand is used in mortars ?
Ans. Sand is used in mortar and concrete for the following purpose:
- It sub-divides the paste of binding material into thin films and allows it to adhere and spread.
- It fills up the gap between the building blocks and spreads the binding material.
- It prevents the shrinkage of the cementing material.
- It allows carbon dioxide from the atmosphere to reach some depth and thereby improve setting power.
2. Cement to sand proportions for various works ?
Ans. Masonry works : 1:6 to 1:8
- Plastering masonry : 1:3 to 1:4
- Plastering concrete : 1:3
- Pointing : 1:2 to 1:3
- Cement: Sand Compressive Strength
- 1:6 = 3.0 N/mm2
- 1:5 = 5.0 N/mm2
- 1:8 = 0.7 N/mm2
- 1:4 = 7.5 N/mm2
- 1:3 = 10 N/mm2
3. What is Proportion of cement, sand and coarse aggregates in concrete ?
Proportion of concrete for type of work respectively are as follow :-
Proportion
1:4:8
1:3:6
1:2:4
1:1.5:3
1:1:2
Nature of Work
Mass concretes like dam foundation course for walls, for making concrete blocks.
Piers, abutments, concrete walls, sill of windows, floors.
Commonly used for reinforced concrete works like beams, slabs, tunnel lining, bridges
Water tanks, shells and folded plates, for other water retaining structures
For machine foundation, footings for steel columns and concreting under water.
4. What is RBC in construction ?
Ans: REINFORCED BRICK CONCRETE (RBC)
It is the combination of reinforcement, brick and concrete. It is well known fact that concrete is very weak in tension.
Hence in the slabs, lintels and beams the concrete in the portion below the neutral axis do not participate in resisting the load. It acts as a filler material only.
Hence to achieve economy the concrete in tensile zone may be replaced by bricks or tiles. Dense cement mortar is used to embed the reinforcement. The reinforcement may be steel bars, expanded mesh etc.
5.What is CELLULAR CONCRETE ?
Ans:-It is a light weight concrete produced by introducing large voids in the concrete or mortar.
Its density varies from 3 kN/m3 to 8 kN/m3 whereas plain concrete density is 24 kN/m3. It is also known as aerated,
foamed or gas concrete.
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