Cement and Types of Cements...

Cement and Types of Cements Any substance which bonds materials is normally considered as cement. There are many types of cements. However in construction, the term cement generally refers to bonding agents that are mixed with water or other liquid, or both, to produce a cementing paste. Initially, a mass of particles coated with the paste is in a plastic state which can be formed, or moulded, into various shapes. Such a mixture is normally considered a cementitious material since it can bond other materials together. After a time, due to chemical reactions, the paste sets and the mass harden. When these particles consist of fine aggregate (sand) then mortar is formed. When these particles consist of fine and coarse aggregates then concrete is the result. In its simplest form, concrete is a mixture of paste and aggregates. The paste, composed of portland cement and water, coats the surface of the fine and coarse aggregates. Through the chemical reaction which is called hydration, the paste hardens and gains strength to form the rock-like mass known as concrete. Within this process lies the key to a remarkable trait of concrete is that it is plastic and malleable when newly mixed, strong and durable when hardened. Concrete’s durability, strength and relatively low cost make it the backbone of buildings and infrastructure worldwide houses, schools and hospitals as well as airports, bridges, highways and rail systems. It is the most-produced material on the mother earth. Even construction professionals sometimes incorrectly use the terms cement and concrete interchangeably. Cement is actually an ingredient of concrete. It is the fine powder which, when mixed with water, sand, and gravel or crushed stone (fine and coarse aggregate), forms the rock-like mass known as concrete. Though the history of cementing materials is...