Characteristics of Blended Cements Produced from Selected Hardwood Ashes

Abstract

In an attempt to find an alternative binding material for construction industry, this study considered the use of wood ash from three different hardwoods namely: Tectonagrandis, Cassia siamea and Vitellariaparadoxa as a pozzolan in cement production. The study investigates the chemical composition (silica (SiO2), aluminum oxide (Al2O3), ferric oxide (Fe2O3), calcium oxide (CaO), magnesium oxide (MgO), sulphur trioxide (SO3), sodium oxide (Na2O) and potassium Oxide (K2O)) of the ashes and the clinker. The production of blended cements were carried out in the factory by replacing 5- 50% by weight of Ordinary Portland Cement Clinker with the ashes during the manufacturing process. The cement without wood ash serves as the control. The physical characteristic (fineness, initial and final setting times, heat of hydration and residue on 45µm sieve), and the chemical composition of the blended cements were also investigated. The results showed that all the wood ashes (Tectonagrandis ash (TGA), Cassia siamea ash (CSA) and Vitellariaparadoxa ash (VPA)) were suitable material for use as pozzolan since they satisfied the requirement for such a material by having a combined SiO2, Fe2O3 and Al2O3 of more than 70%. The TGA, CSA and VPA blended cements satisfied standard requirements for up to 20% replacement level. It was concluded that all the wood ashes were suitable for use in the production of blended cements.