Water entrainment and sorptivity characteristics of biochar clay bricks

In this study, biochar derived from rice husk and sugarcane bagasse (usually considered agricultural waste in India) are used for the formation of clay bricks which are very widely used in most developing countries. The basic properties of biochar that made it a good substitute to the clay in the clay bricks were increased strength, water absorption and humidity control, insulation due to the entrapment of air in the micro porous structure of biochar. During the study it was found that biochar produced from agricultural waste had a better porous structure and hence provided better insulation that biochar formed using any other This study examined the feasibility of such clay bricks formed by partial replacement of clay with biochar, which was formed using sugarcane bagasse and rice husk in a 1:1 ratio. The biochar formed was crushed and passed through a 75 micron sieve. This biochar formed was used directly without any additives. The bricks were made in addition of 5% biochar up to a total of 20%. The bricks formed using more than 20% biochar concentration were rejected as cracking was observed in the brick samples. 10 of these biochar - clay bricks for each increment were formed. The biochar - clay bricks were sundried and then fired in a kiln at different temperatures. The quality of bricks was analyzed for water absorption and efflorescence. The biochar - clay bricks were cured and their corresponding absorptive tendency and alkali presence was determined. The bricks with 15% by weight biochar - clay composition and 15 day curing were found to show least efflorescence while the absorptive nature of the bricks was found to increase slightly.