Pierment And Cement Replacement Materials

1.8 Cement& Cement Replacement Materials

A comprehensive review on cement (OPC) and cement replacement materials like fly ash and silica fume, which are being used for developing SCC are discussed in following paragraphs;

1.8.1 Cement

Cement, in broader sense can be defined as the material having cohesive and adhesive characteristics which is capable of bonding the minerals parts into confined mass. This characterization covers large verity of cementing materials.

Cement is combination of powder mix of several minerals. It production involves mixing calcareous materials like chalk, limestone which contains silica and alumina. Final product obtained after heating up to 1450oC is called clinker in a cool form. This cooled clinker is then excellently mixed and ground with addition of 3-5% of gypsum which contains calcium sulphate in its content. Amount of gypsum regulate the physical characteristics of the conventional concrete. Occasionally very little amounts of pigments are also inducted. However cement manufacturing methods do vary.

Cement as a material comprises mainly ground clay and lime which becomes a stiff mass when diversified with water and is used in concrete

Silica fume powder exhibits off-white to grey colour, and accessible in various product forms including packaging choices. When employed in cementitious applications (concrete, shotcrete, repair products and oil well grouts), silica fume performs together as filler (refining the physical structure through filling the voids among cement particles) and as pozzolan (reacting chemically to induce higher strength and toughness to the concrete under consideration. Standard provisions for SF employed in cementitious mixtures are in ASTM C1240. It is frequently used at replacement levels of 5% to 12% by quantity of entire cementitious