Effect of lignosulfonate, calcium chloride and their mixture on the hydration of RHA-blended portland cement

Hydration of 10 wt.% rice husk ash (RHA)-blended Portland cement has been studied in the presence of 2 wt.% CaCl2, 1 wt.% lignosulfonate (LS) and a mixture of the two admixtures by using different methods. Free lime determinations and differential thermal analysis have shown that CaCl2 accelerates the pozzolanic reaction of Ca(OH)2 and RHA. In the presence of mixture of two admixtures, lower amount of water is required for consistency of the paste. IR spectral studies have supported that the mixture of the two admixtures act as a strong accelerator for cement hydration. The compressive strength is highest in the presence of a mixture of the two admixtures at 28 days of hydration. The admixtures did not prevent the deterioration of the blended cement in corrosive atmosphere.