Evaluating the effects of agricultural wastes on concrete and composite mechanical properties: a review

Wastes generation and emission of greenhouse gases are the major concerns of the contemporary world. Concrete's cements companies in the globe are producing up to 2.8 billion tons of cements annually. This contributed to the emission of anthropogenic substances into the atmosphere which destroys the ozone layers. The incessant disposal of these agricultural wastes has detrimental effect on the environmental and human health. Thus, utilizing these wastes as secondary resources in concrete is a reasonable consideration in sustainable waste management in the circular economy. The use of agricultural wastes in concrete production has been gaining attraction in recent years, however, their effectiveness and performance in concrete need evaluation. This study presents an overview of the effects of some agricultural wastes: Bagasse, Coconut shell, Cotton, Oil palm and Hemp fibers on concrete and composite's mechanical properties. As reviewed, Sugar-Cane Bagasse Ash (SCBA) and Coconut Shell Ash (CSA) are rich in cementitious (pozzolanic) properties (SiO2, Fe2O3 and Al2O3) for cement production up to 70%. Sugar-cane bagasse and oil palm-fiber ashes improved concrete workability. SCBA and CSA highly increased the concrete compressive strengths. The concrete tensile strengths were increased up to 97% with the inclusion of cotton and bagasse ashes. The SCBA, hemp-fiber and treated oil palm - fiber ash increased the concrete and composite's flexural strengths up to 11.3%, 26.2% and 50.7% respectively. In conclusion, the output of this review will supply full data of the research gaps yet to cover on the use of agro-wastes in concrete for future investigations.