Review on Performance Evaluation of Autonomous Healing of Geopolymer Composites

Abstract

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.

A State-of-the-Art Review on Innovative Geopolymer Composites Designed for Water and Wastewater Treatment

“…The valorization of diverse and profound wastes of dissimilar origin is one of the pillars of this novel concept. The innovative geopolymer technology facilitates the application of numerous waste streams as either a precursor or as add-on materials, such as fly ash (FA) and glass waste [ 272 , 273 , 274 ], which reduces the consumption of natural mineral resources, such as metakaolin (MK), besides evident eco-pros. These assortments of wastes have raised great concerns vis-à-vis their management strategies.…”

“…A number of aluminosilicate materials and industrial wastes can be utilized to make geopolymers [ 268 ]. In this regard, the physiochemistry features of those materials often vary, which makes ensuring the quality of geopolymer generated problematic [ 269 , 270 , 271 , 272 , 273 , 274 ]. Aside from that, the strength of the geopolymer is a source of worry.…”

Rubberized Geopolymer Composites: Value-Added Applications

“…Not only that, the recycled fibres also entail monetary advantages in construction. Nowadays, greener, inorganic geopolymeric construction composites are appearing to be a most promising substitute for OPC-based systems, with an exhibition of excellent properties, such as higher mechanical attributes, lower creep, less shrinkage, and extraordinary resistance to chemicals such as acid [149][150][151][152][153]. The exothermal process of geopolymerization among alkali solutions and the silica-and alumina-rich source materials of geological or industrial origin at low temperatures is competent enough for manufacturing geopolymer pastes, binders, mortar, and concrete, and for incorporating rubber tyre waste as a replacement for fine and/or coarse natural aggregates to form the rubberized geopolymer construction composites [153,154].…”

The Potential use of Bio-mineralization Technique in Developing Eco-Sustainable Self-Healing Geopolymer Binder: A Systematic Review

“…The mechanisms involved in the autogenous healing of concrete includes formation of calcium carbonate, settlement of loose cement particles in water, hydration of un-hydrated particles and swelling of the hydrated cementitious system. The calcium carbonate precipitation to achieve autogenous healing with the incorporation of bacteria into cementitious system is depicted below [20]:…”

“…The autogenous self healing of the geopolymers stands for imparting a natural ability to mend themselves from cracks. The life cycle assessment of BMGP implies the reduction in environmental impacts due to its production [20]. The present study aims at reviewing the type of bacteria used by various authors in developing BMGP, mechanical and durability characteristics of BMGP, microstructural characterization of BMGP and the various applications reported in the literature.…”