Valorization of waste powders from cement-concrete life cycle: A pathway to circular future

Maintaining equilibrium between the three pillars of sustainability (social, economic, and environmental) is very important for the sustainable construction industry. Every phase of the cement-concrete life cycle, from the production of cement to concrete application and finally demolition, a considerable amount of carbon dioxide (CO₂) and solid waste are generated. In fact, the produced solid wastes in particular in the form of powder, for example, cement kiln dust (CKD), concrete fines, etc., are rich in Ca could be a possible source to sequestrate CO₂ and use as valuable construction materials. This review focuses on the origin, physico-chemical aspects, various valorization routes as well as the potential applications of waste powders sourced from the cement-concrete life cycle. Utilization of waste powders generated in the concrete life cycle in the production of new concrete, bricks, paver blocks, and other construction applications could offer the construction industry with sustainability benefits. A number of studies also demonstrated that it is feasible to turn these wastes into artificial aggregate and produce pure calcium carbonate via mineral carbonation. However, further research on engineering performance, environmental impacts (carbon credits), and economic benefits should be systematically carried out before these products can be introduced to the construction sector.