Development of sustainable bricks using ash from co-fired sawdust and coal

Ash obtained from co-combustion of sawdust and coal was studied to determine its potential to be used as an alternative construction material. The ash was subjected to chemical, physical and mineralogical characterisation. It was then mixed with cement and sand in various proportions and made into bricks. These were tested for compressive strength, density, water absorption, efflorescence, durability (chloride and sulfate) and thermal conductivity. The equivalent energy required during production of the bricks was compared with commercially available fly-ash (FA) and burnt-clay bricks. The produced bricks complied with Indian standards. A comparative analysis showed that the bricks were 26% and 15% lighter and 50% and 58% less thermally conductive than FA and burnt-coal bricks, respectively. Also, the embodied energy was 19% and 48% less than that of FA bricks and burnt-coal bricks, respectively. The overall study suggested that the sawdust–coal ash bricks are energy efficient, lighter in weight and better in thermal performance as well as providing a sustainable solution to meet the increasing demand for construction materials.