A state of the art review to enhance the industrial scale waste utilization in sustainable unfired bricks

Manufacturing of unfired bricks, in which fines are stabilized using cementitious or chemical binders, has huge potential to incorporate various wastes as a building construction material. Although researchers have successfully attempted various wastes in unfired bricks at the laboratory scale, their industrial-scale incorporation is still limited and unexplored. From an industrial point of view, mix proportions, mixing strategies, molding methods, and curing conditions are of equal importance. However, the unavailability of comprehensive knowledge related to manufacturing aspects hampers the industrial-scale implementation of research outcomes regarding waste incorporation in unfired bricks. This study summarizes the research outcomes related to waste incorporated unfired bricks, highlighting the manufacturing aspects from the industrial point of view. In this paper, mix proportions attempted, approaches for selecting the liquid content, adopted mixing strategies, compaction parameters, and curing conditions in previous studies are discussed for various waste incorporated bricks. Studies are classified based on the binder used for stabilization, and the effects of influencing parameters on the mechanical performance of bricks are discussed in detail. Furthermore, some industrial challenges related to unfired brick production in Indian scenario are discussed. Studies related to mixture proportioning, mixing optimization and hybrid curing development for a multi-waste incorporated system are expected to be future research trend for waste stabilization in unfired bricks. The comprehensive knowledge presented here is expected to support in the selection of suitable manufacturing aspects, which in turn enhances the waste utilization in unfired bricks at an industrial scale.