Review on Performance Evaluation of Autonomous Healing of Geopolymer Composites

It is a universal fact that concrete is one of the most employed construction materials and hence its exigency is booming at a rocket pace, which in turn, has resulted in a titanic demand of ordinary Portland cement. Regrettably, the production of this essential binder of concrete is not merely found to consume restricted natural resources but also found to be associated with emission of carbon dioxide—a primary greenhouse gas (GHG) which is directly answerable to earth heating, resulting in the gigantic dilemma of global warming. Nowadays, in order to address all these impasses, researchers are attracted to innovative Geopolymer concrete technology. However, crack development of various sizes within the concrete is inevitable irrespective of its kind, mix design, etc., owing to external and internal factors viz., over-loading, exposure to severe environments, shrinkage, or error in design, etc., which need to be sealed otherwise these openings permits CO2, water, fluids, chemicals, harmful gases, etc., to pass through reducing service life and ultimately causing the failure of concrete structures in the long term. That is why instant repairs of these cracks are essential, but manual mends are time-consuming and costly too. Hence, self-healing of cracks is desirable to ease their maintenances and repairs. Self-healing geopolymer concrete (SHGPC) is a revolutionary product extending the solution to all these predicaments. The present manuscript investigates the self-healing ability of geopolymer paste, geopolymer mortar, and geopolymer concrete—a slag-based fiber-reinforced and a variety of other composites that endow with multifunction have also been compared, keeping the constant ratio of water to the binder. Additionally, the feasibility of bacteria in a metakaolin-based geopolymer concrete for self-healing the cracks employing Bacteria-Sporosarcina pasteurii, producing Microbial Carbonate Precipitations (MCP), was taken into account with leakage and the healing process in a precipitation medium. Several self-healing mechanisms, assistances, applications, and challenges of every strategy are accentuated, compared with their impacts as a practicable solution of autogenously-healing mechanisms while active concretes are subjected to deterioration, corrosion, cracking, and degradation have also been reviewed systematically.