An empirical study on the thermal behavior of rice husk in eco-friendly brick for external walls of buildings

This study aims to analyze the behavior of natural and waste materials when applied to building brick for walls of residential buildings on the indoor temperatures and thermal comfort of residential buildings. In this study, small-scale residential rooms were built during a period of hot weather in Egypt. A comparison between models and a reference model using the traditional burned clay brick was conducted. The results indicate that the mud-brick leads to enhanced thermal behavior by 25% within comfort limits and the surface temperature difference could reach 4.3 K, whereas the compacted bricks achieve 15%, and the temperature difference was found to be 4 K; compared with the traditional fired bricks with 2.1 K surface temperature difference. Scanning electron microscopy showed large holes and cavities in the mud and compacted bricks. Whereas, in the fired clay brick small holes were observed; this difference in structure is hypothesized to lead to the difference in the thermal behavior of the bricks. The thermal conductivity(U), of the unfired mud-brick, was 0.27 W/m.K, U =0.32 W/m.K for compacted soil brick while burned bricks U=0.6 W/m.K. Based on the results, the combinations of rice husk as a waste material, mud, and compacted soil for brick lead to reducing cooling needs and sustainable building materials for new buildings in the hot and dry climate in Egypt .