Cementitious materials deteriorate progressively with the formation of cracks that occur due to diverse physical, chemical, thermal, and biological processes. Numerous strategies have been adopted to obtain cement-based self-healing materials and determine the novel self-healing mechanisms. The uses of microbes have been established to improve the thickness of the healed crack and mechanical properties of the concrete, a phenomenon seldom addressed in the literature. Based on these factors, this article comprehensively appraises the smart bio-agents-based autonomous healing performance of concrete to demonstrate the recent progress, expected benefits, and ongoing challenges. The fundamentals, design strategies, and efficacy of the smart bio-agents-activated self-healing cementitious materials are the recurring themes of this overview. Furthermore, the effects of various processing parameters on the performance of cementitious self-healing smart bio-agents are discussed in-depth. The achievements, knowledge gaps, and needs for future research in this ever-evolving area for the sustainability and resilience of the built environment are highlighted.

Various alkali-activated binders (AABs) incorporated with different industrial wastes emerged as useful environmental affable materials in the construction sectors as alternative to the traditional cement due to their lower CO₂ emission and landfill problems mitigation. The sustainability of concretes is the major global concern in the construction sectors. In this view, the effects of waste glass bottles-derived nanopowder (WGBNP) on the durability characteristics of five batches of alkali-activated mortars (AAMs) with the inclusion of fly ash (FA) and ground blast furnace slag (GBFS) were evaluated. These AAMs were designed via the replacement of GBFS at various WGBNP contents (0%, 5%, 10%, 15% and 20%). Analytical tests were performed to determine the mortars compressive strength, porosity, drying shrinkage, and resistance to aggressive environments. Microstructures characteristics were assessed using XRD measurements. Replacement of GBFS by WGBNP was found to remarkably improve the durability traits of the produced AAMs, solving the environmental and landfill problems. The results indicated that the inclusion of 5% of WGBNP in alkali-activated matrix led to the reduction of porosity and enhancement of the strength and durability performance. Additionally, the replacement of GBFS by WGBNP was found to improve the durability performance in terms of reduced drying shrinkage and increased resistance to sulphuric acid, wearing, and freeze-thaw cycles. The obtained AAMs were demonstrated to be environmentally beneficial regarding the lowering of global warming.

Nowadays, an alkali-activated binder has become an emergent sustainable construction material as an alternative to traditional cement and geopolymer binders. However, high drying shrinkage and low durability performance in aggressive environments such as sulphuric acid and sulphate are the main problems of alkali-activated paste, mortar and concrete. Based on these factors, alkali-activated mortar (AAM) binders incorporating high-volume palm oil fuel ash (POFA), ground blast furnace slag (GBFS) and fly ash (FA) were designed to enhance their durability performance against aggressive environments. The compressive strength, drying shrinkage, loss in strength and weight, as well as the microstructures of these AAMs were evaluated after exposure to acid and sulphate solutions. Mortars made with a high volume of POFA showed an improved durability performance with reduced drying shrinkage compared to the control sample. Regarding the resistance against aggressive environments, AAMs with POFA content increasing from 0 to 70% showed a reduced loss in strength from 35 to 9% when subjected to an acid attack, respectively. Additionally, the results indicated that high-volume POFA binders with an increasing FA content as a GBFS replacement could improve the performance of the proposed mortars in terms of durability. It is asserted that POFA can significantly contribute to the cement-free industry, thus mitigating environmental problems such as carbon dioxide emission and landfill risks. Furthermore, the use of POFA can increase the lifespan of construction materials through a reduction in the deterioration resulting from shrinkage problems and aggressive environment attacks.