Use of fused laterite powder as a partially replacement for cement in concrete

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November 2015
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The high cost of Portland cement (which is produced from imported raw material) in Ghana makes building construction very expensive thereby making many people unable to afford. Consequently, there is a quest to find a substitute for cement. Fused laterite (Laterite rock) is a material abundant in Ghana which naturally portrays the properties of a cementitious material. However, knowledge on this local material is limited. Thus the current study aimed at exploring the properties of this material and its effects on the strength of concrete when used as partial replacement of cement in concrete production. To achieve this 150mm concrete cubes and 150mm x 300mm concrete cylindrical specimen were cast and tested for their compressive and split tensile strengths respectively. Chemical analysis of the material was also carried out to find out the compounds/oxides present in the fused laterite. The results revealed that the most dominant chemical in fused laterite is Calcium Oxide (CaO) which represents 19.2% followed by Silica oxide (2.8%), Sulphur oxide (2.5%), Magnesium oxide (1.94%), Sodium oxide (0.06%) and Potassium oxide (0.04%). Thus fused laterite contains a majority of the oxides (chemicals) present in Ordinary Portland cement. However, the quantities of the chemicals are small compared with that in Portland cement thereby making it difficult to be used solely as the binding agent in concrete production. Moreover, fused laterite reduces the compressive and split tensile strengths of concrete as its content in the mix increases. The above effect was attributed to the fact that fused laterite contains little amount of silicate (the primary chemical responsible for strength development). Thus, as more of the fused laterite is used, the content of silicate in the mix is reduced hence a weak concrete is produced. Based on the findings, recommendation was made for further studies to find an effective way of using fused laterite for the production of cement.
A thesis submitted to the Department of Building Technology, College of Art and Built Environment, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirement for the Degree of Master of Science in Construction Management,