Mechanical and durability analysis of eco-friendly light weight cement blocks using raw rice husk as a partial replacement for manufactured sand

Abstract

The study investigates the mechanical and durability properties of cement blocks made by partially replacing manufactured sand (M-sand) with raw rice husk (RRH). The rising demand for sand in construction, coupled with the environmental impact of its extraction, has prompted the exploration of alternative materials. RRH, a byproduct of rice milling, offers an eco-friendly substitute for sand. The research examines blocks containing varying proportions of RRH (20 %, 40 %, and 60 %) and compares treated and untreated husks. Key parameters, including compressive strength, tensile strength, density, performance when exposed to heat, and water absorption, were analyzed. The results show that up to 40 % of RRH can be used to replace sand without compromising the blocks' structural integrity. Treated RRH blocks demonstrated better bonding with cement, leading to higher compressive and tensile strengths compared to untreated ones. A 40 % RRH replacement achieved an average compressive strength of 3.57 MPa, surpassing the minimum requirements for non-load-bearing masonry units as per Sri Lankan and Australian standards. However, increasing RRH content to 60 % significantly reduced strength and durability. Additionally, RRH blocks exhibited a decrease in density, offering advantages in terms of transportation and handling. Water absorption increased with higher RRH content due to its porous nature yet remained within acceptable limits for treated blocks. These findings suggest that RRH can be a sustainable alternative to sand in masonry applications, especially in rural and eco-conscious construction.