Study of the use of Agricultural Waste as a Supplementary Cementitious Material

The use of supplementary cementitious materials has attracted attention in recent years both for their potential applications and beneficial cost in the construction industry. Supplementary cementitious materials can be of mineral or plant origin. Agricultural waste (agro-waste) is under focus especially in low and middle income countries as a source for fuel and also as a construction material. Such use comes either as a stand-alone material or as a cement replacement in concrete materials. The wider use of such materials in construction is considered as potential sustainable alternatives to Portland cements. This paper discusses the prospective use of certain agro-wastes as a partial replacement for cement in concrete mixes and stabilised earth bricks. The materials considered in this study have included: corncob, sorghum husk, sorghum stalk, peanut husk and sesame stalk ashes. Selected agro-wastes have been incinerated under controlled temperature conditions at 500°C and 700°C. The resultant ashes have been characterised using Thermal Gravimetric Analysis (TGA), Energy Dispersive X-Ray Analyser (EDX) and X-Ray Diffraction Analysis (XRD) methods. Silica, used as a pozzolanic indicator, was found to be present in varying quantities. More tests to verify suitability and determine the feasibility of these agro-wastes are currently underway. The paper presents the preliminary results and outcomes, and describes proposed methodology for future tests.