Concrete is a stone like substance obtained by permitting a carefully proportioned mixture of cement, sand and gravel or other aggregate and water to harden in forms of the shape and of dimensions of the desired structure.
Reinforced cement concrete:
Since concrete is a brittle material and is strong in compression. It is weak in tension, so steel is used inside concrete for strengthening and reinforcing the tensile strength of concrete. The steel must have appropriate deformations to provide strong bonds and interlocking of both materials. When completely surrounded by the hardened concrete mass it forms an integral part of the two materials, known as “Reinforced Concrete“.
Advantages and disadvantages of reinforced concrete
Reinforced Concrete is a structural material, is widely used in many types of structures. It is competitive with steel if economically designed and executed.
Advantages of reinforced concrete
- It has relatively high compressive strength
- It has better resistance to fire than steel
- It has long service life with low maintenance cost
- In some types of structures, such as dams, piers and footings, it is most economical structural material.
- It can be cast to take the shape required , making it widely used in pre-cast structural components.
- It yields rigid members with minimum apparent deflection.
- Yield strength of steel is about 15 times the compressive strength of structural concrete and well over 100 times its tensile strength
- By using steel, cross sectional dimesions of structural members can b ereduced e.g in lower floor columns
Disadvantages of reinforced concrete
- It needs mixing, casting and curing, all of which affect the final strength of concrete.
- The cost of the forms used to cast concrete is relatively high.
- It has low compressive strength as compared to steel (the ratio is about 1:10 depending on material) which leads to large sections in columns/beams of multistory buildings Cracks develop in concrete due to shrinkage and the application of live loads