Properties of Cement Concrete
The cement concrete possesses the following important properties:
- It possesses a high compressive strength.
- It is a corrosion resistance material and atmospheric agent has no appreciable effect on it.
- It hardens with age the process of hardening continues for a long time after the concrete has attained sufficient strength. It is this property of cement concrete which gives it a distinct place among building materials.
- It is more economical than steel.
- It binds rapidly with steel and as it is weak in tension, the steel reinforcement is placed in cement concrete at suitable places to take up the tensile stresses. This is termed as the reinforced cement concrete or simply as R.C.C.
- Under the following two conditions, it has a tendency to shrink:
- There is initial shrinkage of cement concrete which is mainly due to the loss of water through forms, absorption by surfaces of forms etc.
- The shrinkage of cement concrete occurs as it hardens. This tendency of cement concrete can be minimized by proper curing of concrete.
- It has a tendency to be porous. This is due to the presence of voids which are formed during and after its placing. The two precautions necessary to avoid this tendency are as follows:
- There should be proper grading and consolidating of the aggregates.
- The minimum water-cement ratio should be adopted.
- It forms a hard surface, capable of resisting abrasion.
- It should be remembered that apart from other materials, the concrete comes to the site in the form of raw materials only. Its final strength and quality depend entirely on local conditions and persons handling it. However the materials which concrete is composed may be subjected to rigid specifications.