REINFORCEMENT IN CONCRETE
Reinforced concrete Is the process of strengthening concrete by embedding steel in concrete which act together in resisting compressive strength of the
concrete and tensile strength of the steel.
Reinforced concrete is one of the two structural materials used in engineering construction and building works.
Concrete is strong in resisting compressive stress but comparatively weak in resisting tensile stress.
The tensile strength of concrete is between one tenth and one twentieth of it compressive strength. Steel which has a good tensile strength is cast into a reinforced concrete members in the positions were maximum tensile stress occurs.
A concrete cover of 20mm is sufficient to protect the steel reinforcement from corrosion inside the majority of buildings. But where reinforced concrete is exposed to sea water and abrasion, a 60mm concrete cover is required.
Due to experience of damage cause by fire outbreak in buildings, it has been established that various thicknesses of concrete cover will prevent an excessive loss of strength in reinforcement for a period of time for the occupants to escape from the particular building during the fire outbreak.
The statutory period of time that the concrete cover is to provide protection against the damage by fire varies in size and type of building from half an hour to four hours.
Advantages of Reinforced Concrete
- Reinforced concrete has a high compressive strength.
- It has a good tensile strength.
- Reinforced concrete resist fire outbreak over a period of escape of occupants of a building.
- Durability and stability.
- Reinforced concrete can be economically molded into a nearly limitless range of shapes.
- Low maintenance cost
- Reinforced concrete is more economical in the construction of structures like footings, dams, piers etc.
- It acts like a rigid member with minimum deflection.
Disadvantages of Reinforced Concrete
- The tensile strength of reinforced concrete is about one tenth of its compressive strength.
- The main steps of using reinforced concrete are mixing, casting, and curing. All of this affects the final strength.
- The cost of the forms used for casting reinforced concrete is relatively higher.
- For high-rise building, the reinforced concrete column section is larger than steel section as the compressive strength is lower in the case of reinforced concrete.
- Reinforced concrete without concrete cover is exposed to air, which would rust and loses strength.