Green brick production from rice husk and lake sediment: Energy consumption and optimization

In the past few decades, there has been a growing need to improve energy efficiency in brick production to reduce its environmental impact and support sustainable development. This study investigated the potential of partially replacing clay with treated lake sediment (LS), rice husk (RH), or mixtures of rice husk and treated lake sediment (RH-LS) in fired brick production. The brick samples were tested for density, linear shrinkage, water absorption, and compressive strength. Energy consumption during the firing process was monitored, and a comparison was made between conventional clay bricks and the novel brick formulations. The results revealed that it is possible to fabricate fired bricks using lake sediment blended with rice husk, incorporating up to 45% by weight of the alternative materials. These lightweight bricks met the technical standards for clay brick production, exhibiting a compressive strength exceeding 5.0 MPa, water absorption ranging from 13.8% to 31.3%, and linear shrinkage below 8.0%. The inclusion of LS and, particularly, RH, led to brick samples consuming 13% to 60% less energy and reducing CO₂ emissions by 0.9 to 2.7 times during the firing process. Additionally, the optimal 45% RH-LS brick samples reduced electricity consumption by 41% and CO₂ emissions by 2.3 times during sintering.<i>Implications</i>: Previous studies have demonstrated the feasibility of synthesizing fired-clay bricks by incorporating mixing sewage sludge from different origins (sewage sludge, river sediment, canal sediment, sewer sediment, etc.) with clay and some wastes to make bricks. This study identifies an optimal substitution ratio of 45% clay replacement-comprising 18% rice husk ash and 27% lake sediment. Thermal analysis confirms a maximum energy efficiency at a sintering temperature of 950°C for 3-hours. This integration achieved a 13-60% reduction in specific energy consumption and a 0.86-2.7-fold decrease in CO₂ emissions relative to conventional clay bricks.