concreteCement concrete is the mixture of cement,sand,gravels and water in a definite portion.Due to mixing of this ingredient they form a plastic mass which is furtherly poured over a suitable moulds known as forms.Which gets hard solid mass after setting of the cement concrete.The  chemical reaction between cement and water is slow and requires  more time and need suitable temperature for setting.
The setting time is furtherly categorises in three phases:-
(i) First phase-In this phase it requires 30-60 minutes for complete reaction and setting because concrete decreases its plasticity. It is also called as initial set
(ii)Second phase-After mixing the gradient it may vary from 5-6 hours to set and concrete gets soft without any hardness on its surface.It is also called as final set.
(iii)Third phase-In this phase concrete gets harden and increase its strength.
Concrete has more strength in compression but has less strength in tension.Therefore the plain concrete is not much more applicable because of its low tension strength.But this concrete can be used in beams,slabs etc in common construction structure.
But the tension strength can be high if the steel bars are embedded in the concrete which is known as steel reinforcement.The product from this steel bar and concrete is so obtained is known as reinforced cement concrete or R.C.C.

It is further classified on:-

(i)  Portland cement
(ii) High alumina cement
(iii)Natural cement
(iv)Super sulphate cement
(v) Special cement