Rice Husk Ash as Partial Replacement of Cement in Sustainable Construction

Abstract

Alternative construction materials derived from agricultural waste, such as rice husk ash (RHA) and groundnut shell ash, have enhanced the sustainability and performance of concrete structures. The use of these ash materials, with their inherent pozzolanic and mineral admixture properties, has received much attention in the construction industry due to their potential benefits. In this experimental investigation, we assessed the attributes of cement paste incorporating RHA as a pozzolanic substitute. Various replacement ratios, ranging from 0% to 25% by weight of the binder, were examined at different water-to-binder ratios (0.40, 0.45, 0.50, and 0.55). Cementitious specimens were cast in 50mm x 50mm x 50mm cube molds, cured for seven days, and subjected to compressive strength testing. The findings highlight the impact of water-to-binder ratios and cement replacement levels on the compressive strength of cement paste. Higher water-to-binder ratios were associated with reduced compressive strength in the hardened paste. The optimal cement replacement levels were observed at 15% for the hardened blended paste specimens for all water-to-binder ratios. Two empirical regression models (polynomial and power) were employed to analyze the relationships between the paste’s replacement ratios, water-to-binder ratios, and compressive strength. The models revealed consistent findings, with the power model demonstrating an inverse relationship between compressive strength and water-to-binder ratios, while the polynomial model’s coefficients indicated a positive correlation between replacement ratios and compressive strength