| Cement is a fine powder, which when mixed with water undergoes chemical change and thereafter allowed to set and harden is capable of uniting fragments or masses of solid matter together to produce a mechanically strong material. Cement can be used as binding material with water, for bonding solid particles of different sizes like bricks, stones or aggregate to form a monolith. Cements used in construction of buildings and civil engineering works contain compounds of lime, silica and alumina as their principal constituents and can be called as complex compounds.
Importance of cement in construction
Today, cement is a very important building material used in the construction industry. It was in 1824 that cement, as we know it today was developed. Joseph Aspdin of England first patented the manufacture of a very improvised type of cementitious material for building construction in 1824. The hardened cement paste resembled the natural stone occurring at Portland in England. Hence it was named as Portland cement.
Cement has replaced all other binding materials, for example, clay and lime, which ruled high for hundreds of years, in construction from last century. The reason being that, cement is the strongest binding material amongst clay, lime and cement.
Cement is now used in many construction trade items like Plain Concrete, Reinforced Concrete, Mortar, Plaster, Grouts, Paints and in Pre-cast Elements. In an ordinary building construction the cement accounts to about 15-17% of the cost of construction. In some other major constructions like concrete roads and bridges, it is very much more.
Some of the reasons for its popularity and universal acceptance are listed below:
- Cement can be produced in large volumes in controlled condition, packed and transported
- Cement is several times stronger binding material than lime and clay
- It can be mixed and used at will with locally available materials at site
- When stored properly in ordinary atmosphere does not deteriorate for reasonably longer time
- When mixed with water, starts setting and acquires sufficient strength in a day or two, where as other binding materials require much longer time
- When water is added to quick lime, lot of heat is generated, but in case of cement, heat generated is unnoticeable and comparatively much lesser
- It can withstand compressive stresses well. Where tension and shear stresses occur it gives good bond to steel reinforcement and transfers excess stresses to steel
- It is produced from the materials like limestone, hematite, bauxite, clay, etc which are abundantly available in the upper crust of the earth