Effect Of Superplasticizer on Setting Time and Strength of Mortar Made Using Rice Husk Ash (RHA) and Calcium Carbide Waste (CCW) As Binder

Abstract

Consequent to the challenge of global warming partly associated to high CO2 emission and energy consumption from cement production processes, research focus has shifted to sourcing alternatives to Portland cement in concrete and mortar production. Incinerated ashes from agro-wastes such as Rice Husk Ash (RHA) at controlled temperature has been found to be pozzolanic with major components been amorphous silica which combines with lime in the presence of water to give cementitious properties. RHA – CCW binder has however been reported to be of high water demand, slow setting rate and strength development. This study incorporates a superplasticizer (Master Glenium ACE 456) – a water reducing agent and set accelerator as an attempt at overcoming the limitations of this new binder. Pastes of 1:3 binder: sand (b:s) and 0.5 water cement (w/c) ratio in accordance to BS EN 197: 2000 made from the different proportion combinations of RHA – CCW were examined for influence of superplasticizer on setting times, degree of hydration and strength development. The study showed that the superplasticizer enhanced early setting and strength development of the mortar. Mortar samples from 60/40 RHA – CCW binder showed superior performance over the other percentage blends with respect to 28 days compressive strength.