Concrete is a mixture of cement, aggregate( both coarse and fine), admixtures( chemical and mineral) and water used in foundation, RCC beams, columns slabs, etc.
The requirements of a high-quality concrete are essential for the adequate strength development required to bear various dead and live loads over it.
The quality of cement should necessary be checked from different field tests including the reading of the manufacturing date and the prescription of time of use. Ensuring presence of no lumps by crumbling the cement in your hands and a rough estimation of excessive silt content by forming cement balls and letting them dry in the sun( excessive sand in cement will create cracks and warping of cement balls). According to the visual appearance( the cement is greyish in colour with a tint of greenish shade in it) and using different types of cement according to the need( construction of dams and abutments use low heat cement.
Pozzolanic and Portland cement find a use for house construction of pillars, columns and roof slabs; rapid hardening white cement is utilised for whitewashing the walls.
The most used type of cement in the world is the ordinary portland cement first invented by Joseph Aspirin, a worker; the cement soon became the most used in construction.
However, the cement possesses moderate properties of the heat of hydration and reduced resistance to sulphate attack making it impossible to use for marine structure exposed to harsh conditions of attack of seawater. This incident forced scientists to develop the new type of cement to be utilised by the need of the work.
When researchers were carried out, researchers found out four compounds formed after the reaction of argillaceous and siliceous materials which they named as Bogue compounds. It includes dicalcium silicate, tricalcium silicate, tricalcium aluminate and tetra calcium aluminium ferrite.
Tricalcium silicate is the best ingredient present in the cement and is responsible for the development of initial strength of cement for up to 7 days.
Dicalcium silicate it is the compound which provides strength after seven days and up to 28 days and thus helps in the development of the ultimate strength of the cement.
Tricalcium aluminate is the first compound to hydrolyse as soon as the water gets into the cement, a cement having the higher percentage composition of this compound would have the greater heat of hydration, and its use is discouraged in the construction of mass concrete structures such as dams, bridge abutments and spillways.
Rapid hardening cement: there are some works including rail and road construction where the entire area cannot remain barricaded for a very long time for fulfilling this purpose the setting time of the cement should be small enough so as to facilitate easy transport. It is achieved using a cement low in the composition of tricalcium silicate.
Oil well cement: for purposes such as grouting, concrete needs to be pumped at very significant depths if ordinary Portland cement is used in these cases this would lead to the setting of the cement before reaching the source of use. The cement required is thus made of longer setting times using less quantity of tricalcium aluminate and increasing the amount of tetra calcium aluminium ferrite.
Thus it can be seen that the correct usage of cement is important in the field of civil engineering.