Hydration of cement
Definition of heat of hydration is the quantity of heat (in joules) per gram of un-hydrated cement evolved upon complete hydration at a given temperature. The amount of heat generated depends upon the chemical composition of cement. The chemical reaction of calcium silicate and calcium aluminate is shown as below.
For chemical reactions of calcium silicate:
2C3S + 7H = C3S2H4 + 3CH ……………………………… (1)
(Tri-calcium silicate) + (water) = (calcium silicate hydrate gel) + (calcium hydroxide)
2C2S + 7H = C3S2H4 + CH …………….……………… (2)
(Di-calcium silicate) + (water) = (calcium silicate hydrate gel) + (calcium hydroxide)
For chemical reactions of calcium aluminate:
2C3A +…show more content… First, the process begins with the addition of water, which surrounds the individual grains of cement. Then, the coating of gel appears around the grains and angular crystals of calcium hydroxide that develop as by product of the hydration of silicate in the mix become evident. Finally, tubular fibrils of the hydration calcium silicate developed. The interlocking eventually binds the cement and other components of the mix into a hard mass known as hardened cement…show more content… However, by adding 20% paper sludge and 20% POFA into cement provide adequate compressive strength up to 8.89 N/mm² that exceed the minimum requirement, tolerable water absorption and acceptable heavy metals leachate.
2. Syahrul Hisyam bin Mohd Sani, M., & Rahman, M. A. (2011). Properties of waste paper sludge ash (WPSA) as cement replacement in mortar to support green technology material. The compressive strength is increasing with increasing of curing age for all mixes. However, the compressive strength decreased when the WPSA increased. The cement is replaced by 50% of WPSA in brick mix gives strength of 16.4 MPa. Meanwhile, by adding 70 & and 100% replacement provide 12.5 MPa and 7.7 MPa respectively.
3. Sharipudin, S. S., Ridzuan, A. R. M., & Mohd Saman, H. (2012). Performance of foamed concrete with waste paper sludge ash (WPSA) and fine recycled concrete aggregate (FRCA) contents. 30% of WPSA replacement had produced higher compressive strength rather than those of other replacements. The addition of FRCA increased the compressive strength in which the maximum replacement level is 10% replacement by mass to sand