Performance of cement mortars and concretes containing coal bottom ash: A comprehensive review

Cement composites like mortar and concrete are the most widely used construction material in the world. Around 90% of the total carbon footprints of concrete manufacturing comes from cement production. The conventional ingredients of the concrete are primarily derived from natural resources like rocks and river beds resulting in the degradation of the natural resources. The growing energy requirements are generally met from the thermal power plants resulting in the generation of an enormous amount of coal ashes that further leads to environmental degradation. An attempt to minimize the environmental impacts of the aforementioned industries requires the utilization of the by-products from the thermal power plants in the manufacturing of mortar and concrete. Coal Bottom Ash (CBA), heavier coarse ash generated and collected from the thermal power plants can be utilized in mortar and concrete manufacturing in two different capacities. The present study summarizes the investigations carried out on fresh, mechanical, and durability properties of the mortar and concrete mixes with CBA as a replacement of fine aggregates and cement. Most of the investigations carried out on the use of CBA encourage the idea of utilizing it as a green material in the manufacturing of mortar and concrete. The present study includes some of the contradictory results, future challenges, and research gaps related to the application of CBA in the construction industry. Further, this review is an effort to provide a substantial base of knowledge, future scopes, and the challenges related to the potential use of CBA as fine aggregates and cement replacement in mortar and concrete, to promote sustainability and cleaner production in the construction sector.