Exploratory Study on Agro-waste Ashes Combination with Industrial Waste as Alternative Binders in Concrete

Abstract

Porland cement (PC), being the world's most commonly used binder in mortar and concrete applications. adjudged a non-environmental-friendly material due to its green house (carbon dioxide-CO emission mainly during its production. Previous studies on the search for alternative binders had centred on the utilisation of natural Pozzolan or ashes from agricultural wastes (agro-wastes) as partial replacement of PC in mortar or concrete construction while reports on total replacement are scarce in literature. Incinerated ashes from agro-wastes at controlled temperatures have been found to be pozzolanic with the major components being amorphous silica which combines with lime in the presence of water to give cementitious properties. This paper reports on the exploratory study on agro-waste ashes namely Rice Husk Ash and Sorghum Husk Ash (RHA and SHA) which are silica sources, in combination with industrial waste materials typically calcium carbide waste (CCW) - a CaO source). as alternative binder for total PC replacement in mortar and concrete construction. Pastes from the different combination ratio of RHA/CCW and SHA/CCW were studied for setting times, degree of hydration and strength development. The study revealed that RHA and SHA have high silica content (SiO-93% and 84% respectively) while CCW primarily contains Ca0 (66% content). The agro-industrial binders (RHAICCW and SHACCH) showed good binding properties at a slow hydration rate. Mortar sample from 60/40 RHAICCW and 70/30 SHA/CCW combinations gave best performance with 28-day compressive strength of 5.3N/mm2 and 7.5N/mm2 respectively and correspondingly representing 25% and 35% of CEM I strength.