What is Cement?

Cement is a hydraulic binder used in the construction and manufactured mixing by fine calcareous (Calcium bearing) and Argillaceous materials (Alumino Silicate) in a predetermined ratio after burning at a temperature (1400-1450°C) in a rotary/vertical shaft kiln. The Clinker so obtained is ground units 2-3% Gypsum to fine powder in cement mill and is called as Ordinary Portland Cement (OPC). It is graded as 33, 43 and 53 grade. The nomenclature is based on minimum ultimate strength (28D) as 33, 43, and 53 MPa or 330, 430 and 530 Kg/Cm2. if clinker is ground with Flyash (15-35%) and gypsum (2-3%) the resultant product is known as Portland Pozzolona Cement (PPC)

How does it work?

When cement reacts with caster and sound it forms gelatinous mass with evolution of heat. The plasticity is lost and rigidity aquarius. It is known as setting. Then it hardness and takes a shape of stony mass known as hardening and goes on attaining strength gradually.

Hydration Mechanism:

Reaction of cement, sand and water makes Tobermorite gel (CSH) with release of lime Ca (OH)2 the lime reacts with Co2 and water and forms bicarbonate, which is soluble in water and is called "Leaching". This reduces the strength and durability of concrete and plaster. The reactive silica of Flyash makes Ca(OH)2 again Tobermorite gel and this reaction continues till all Ca (OH)2 is consumed and makes the concrete structure impervious/dense and strong. This also gradually attains high strength.