What is Ordinary Portland Cement (OPC)?
Ordinary Portland Cement (OPC) is one of several types of cement being manufactured throughout the world. OPC is the general purpose cement used in concrete constructions. OPC is a compound of lime (CaO), silica (SiO2), alumina (AL2O3), iron (Fe2O3) and sulphur trioxide (SO3). Magnesium (MgO) is present in small quantities as an impurity associated with limestone. SO3 is added at the grinding stage to retard the setting time of the finished cement. When cement raw materials containing the proper proportions of the essential oxides are ground to a suitable fineness and then burnt to incipient fusion in a kiln, chemical combination takes place, largely in the solid state resulting in a product aptly named clinker. This clinker, when ground to a suitable fineness, together with a small quantity of gypsum (SO3) is Portland Cement.
Why is it called Portland Cement?
Invented in 1824 by the UK bricklayer Joseph Aspdin (1779-1855), it gets its name from its resemblance upon hardening to the famous Portland limestone obtained from quarries on the Isle of Portland.
The quality of Portland cement is defined by Malaysian Standard MS EN 197-1:2007, which is adopted from European Standard EN 197-1:2000. These standards specify a series of test for which the cement will have to conform to. The most common being :
Types of Cement
|Ordinary portland cement||type I||522||ordinary||General|
|Super High early strength portland cement||type III||522||rich in C3S, finer ground, high early strength||Winter, Urgent|
|Super high early strength portland cement||good particle size distribution, rich in SO3 higher in early strength than type III||Winter, Urgent|
|Moderate heat portland cement||type II||low in C3S, low in C3A, low heat of hydration & high long term strength||Dam, Mass concrete|
|Low heat portland cement||type IV||low heat of hydration, low early strength||Dam, Mass concrete|
|Sulphate resisting cement||type V||1037||low in C3A, high chemical resistance||Underground water|
|White portland cement||888||minute in iron, pure-white, fine ground, high early strength||Buildings, Arts|
|Portland blast furnace slag cement||type IS||1389||low heat of hydration, good chemical resistance, high long term strength, less shrinkage||Dam, Mass concrete|
|Portland pozzolan cement||type IP||blended with siliceous material, low heat of hydration, good durability, good chemical resistance||Civil work, Mass concrete|
|Portland fly-ash cement||1227||good workability & fluidity, slow set, low heat of hydration, high long term strength||Civil work, Pre-packed concrete|
|Super-sulphate slag cement||1388||high long term strength, small shrinkage, easy to aerate||Underwater concrete|
|Masonry cement||794||goodplasticity, water retentivity, water tightness & low shrinkage||Masonry, for joints|
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