Research Progress in Fiber-reinforced Microbial Self-healing Concrete

Abstract

Fibre reinforcement and microbial mineralisation address different but potentially complementary weaknesses of cementitious materials: fibres limit crack opening and sustain post-cracking load transfer, whereas microbial systems can precipitate mineral phases that obstruct transport pathways and partly restore damaged material. Their integration has therefore been proposed as a route towards concrete that is simultaneously tougher and capable of autonomous crack sealing. This critical narrative review evaluates the research progress in fibre-reinforced microbial self-healing concrete, with emphasis on whether reported benefits constitute demonstrable fibre–microbe synergy rather than parallel effects. Accessible scholarly literature was searched through 17 July 2026 and appraised for mechanistic support, experimental controls, crack-conditioning methods, healing endpoints, durability relevance and translational maturity. The evidence is strongest for polypropylene, polyvinyl alcohol and basalt fibres combined with bacterial carbonate precipitation, with emerging work on steel and natural fibres and on engineered cementitious composites. Fibres can improve healing by restricting crack width, providing bridging surfaces and, for some chemistries, promoting calcium-ion retention or mineral nucleation. Yet optical crack closure, water-tightness and mechanical recovery frequently diverge, and many studies labelled as self-healing primarily measure uncracked strength or matrix densification. Claims of synergy are further weakened by the frequent absence of factorial controls and statistical interaction tests. Encapsulation and carrier technologies improve microbial survival but introduce their own effects on porosity, workability and strength. Laboratory studies support functional recovery under favourable moisture conditions, whereas repeated cracking, realistic aggressive exposures, reinforced-element behaviour and field-scale validation remain limited. The central research need is therefore not simply higher healing percentages, but standardised, mechanism-resolving experiments that connect microbial viability and fibre-controlled crack geometry to transport recovery, structural performance, service-life benefit and life-cycle impact.