2.B] Explain briefly i) RCC ii) PCC
Answer:-
Reinforced Cement Concrete (RCC):
RCC full form is reinforced cement concrete, which is a composite material made from concrete and steel reinforcement. As we knew that the concrete is weak in tension and strong in compression. Therefore, Steel reinforcement is added in concrete to improve its tensile resistance.
In the civil engineering field, concrete is a material made of Cement, Sand, Mortar, Admixture, etc, and has a different grade based on strength. As we know that concrete is can resist compression very well, but is very weak in resisting tension. Hence reinforcements are introduced in the concrete wherever higher tensile stress is expected.
When steel is provided in cement concrete it becomes RCC Concrete. The most popular reinforcement is steel. This is due to the fact that steel has high tensile and bond strength compared to others and also provides strong concrete. Steel has a high modulus of elasticity so that it can resist much more high tensile force for the same amount of extension compared to concrete.
Pre-stressed Concrete (PCC):-
Pre-stressed concrete is a form of concrete where initial compression is given in the concrete before applying the external load so that desired stress due to external loads will be counteracted in the desired way during its service period.
Types of Pre-stressing
1. Pre-tensioning
In this method, wires or tendons are tensioned (stretched) at first and concrete is poured later. It creates good bondage between the tendon and concrete. As a result, the tendons are protected from corrosion, and tensions are transferred directly. Tendons are anchored and stretched and the stress is transferred to the concrete when it is hard. Then the tendon tries to get back to the original length but is resisted by the bond between the concrete hence it induces compressive force in it.
2. Post-tensioning
Similar to pre-stressing but here concrete is poured first then tendons are tensioned. Tendons are placed at suitable places in the member and then casting is done. After the concrete becomes hard, the tendons are tensioned (stretched) by hydraulic jacks against the concrete. When the tendons have tensioned sufficiently, jacks are removed, tension remains and it transfers pressure to the concrete. Moreover, post-tensioned concrete is also used in bridges.
