essay on cement city of 450 words
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Answer:
Cement is the main constituent of concrete. It can be defined as a material having adhesive and cohesive properties which make it capable of bonding mineral fragments into a compact mass. Actually this definition covers a large variety of cementing materials. For constructional purposes, the meaning of the term cement is restricted to the bonding materials used with stones, bricks, and sand etc.
The principal constituents of this type of cement are compounds of lime. On adding water to cement a chemical reaction known as hydration of cement takes place and a large quantity of heat-liberates. On hydration of cement, gel is formed which binds the aggregate particles together and provides strength and water tightness to concrete on hardening. Thus cement has the property of setting and hardening under water by virtue of a chemical reaction with it. Such cements are called hydraulic cements. They consist mainly of aluminates and silicates of lime.