Cement | Introduction | Part 1

1. Cement is a material which has cohesive and adhesive properties in the presence of water. 
2. Obtained by pulverizing clinker formed by calcinating raw materials primarily consisting of  Lime (CaO), Silicate (SiO₂), Alumina (Al₂O₃) and Iron oxide (Fe₂O₃).
3. It was invented by Joseph Aspdin of UK in 1824. He named it Portland cement because the hardened concrete made out of the cement aggregates and water in definite proportion resembled the natural stone occurring at Portland.

Note:

i).   Pulverize: Make into a powder by breaking up or cause to become dust.

ii).  Clinker: a hard brick used as a paving stone.

iii). Calcination: the process of heating a substance to a high temperature but below the melting or fusing point causing loss of moisture reduction on oxidation and dissociation into simpler substances.

Classification of Cement used in Construction:

Hydraulic Cement: Set and hardens in the presence of water duwe to hydration and result in water resistant product which is stable. E.g. Portland cement.

Non-Hydraulic  Cement: Derived from calcinations of gypsum or lime stone because their products of hydration are not resistant to water however the addition of pozzolonic material can render gypsum and lime cement and hydraulic. E.g. Plaster of Paris. 

Cement can be manufactured either from natural cement stones or artificially by using calacareous and argillaceous materials.

Calcareous: Which contains calcium and magnesium for e.g. limestone, chalk and marine shells.

Argillaceous: Which contains silica, alumina and oxides of iron for e.g. clay, cement rocks, blast furnace slag and marl.