Developing greener concretes from spent bleaching earth and sugarcane bagasse ash

Abstract

Concrete is by far the most widely utilized construction material due to its excellent mechanical and durability properties. However, the concrete industries are notorious for their anthropogenic activities that contribute to climate change. Cement production alone consumes immense amounts of energy and trails a significant CO2 footprint. One solution that researchers have deemed promising over the last couple of decades is the substitution of cement with agricultural waste products, which subsequently serves to alleviate waste disposal problems. This study investigates the suitability of spent bleaching earth (SBE) and sugarcane bagasse ash (SCBA) as partial replacement of ordinary Portland cement (OPC) in increments of 0, 5, 10 and 15% by mass. Tests were conducted in accordance to British Standards to assess the consistence, compressive strength, split tensile strength and drying shrinkage strain of SBE and SCBA based concretes. Results indicated that while these concretes displayed similar degrees of consistency, the SCBA concretes exhibited superior compressive and tensile strengths. Optimum SCBA dosages were revealed to be about 5-10%, yielding a 7-12% and 3-8% increase in compressive and tensile strengths, respectively, as compared to OPC concrete. Drying shrinkage behavior was also improved in the SCBA concretes. Further, comparisons of the mechanical and durability performances of the concretes with British and American codes suggest that up to 10% replacement of cement with SCBA may be a viable approach to developing sustainable materials for the concrete industry.