An investigation on the mechanical and microstructural properties of pigeon pea stalk ash concrete: an approach towards environmental sustainability

Abstract

The concept of sustainability in agricultural residue management has gained significant attention worldwide in recent years. After harvesting, large volumes of waste are generated, often dumped into the environment, contributing to pollution. However, these wastes can be used in the concrete industry to reduce the depletion of mineral resources, thus preventing environmental degradation. This approach supports sustainable development. In this investigation, the effect of pigeon pea stalk ash (PPSA) as a partial cement replacement in concrete was evaluated through a series of experimental tests. The results indicate that compressive strength increases when 4 to 8% of the cement is replaced with PPSA. However, beyond 8% replacement, the strength decreases. Based on the experimental findings, concrete with 8% PPSA demonstrated a 6.96% increase in compressive strength. Further increases in PPSA content led to a reduction in compressive strength. Although the split tensile strength of 8% PPSA concrete was similar to that of the control concrete, it outperformed other replacement levels. Additionally, concrete with 8% PPSA exhibited higher flexural strength compared to the control concrete. PPSA concrete, prepared with up to 8% pigeon pea stalk ash as a cement substitute, also showed reduced permeability and greater resistance to acid attack. All strength and durability test results confirmed that PPSA concrete was superior to control concrete in terms of mechanical properties and durability. This study highlights the improved economic and environmental benefits of using pigeon pea stalk ash in concrete, pointing to the significant potential for incorporating agricultural wastes like PPSA in sustainable, green concrete.