Synergistic enhancement of strength and durability in self-healing concrete using treated pineapple fibres and bacterial mineralization.

Conventional cement concrete is inherently brittle and susceptible to microcracking, which compromises durability and long-term performance. In order to remediate such conditions, the current research explores the integration of bacterial wollastonite and alkali-treated natural pineapple leaf Fibres (PALFs) to enhance mechanical, durability, and self-healing performance in cement concrete composite. A consortium of microbial system comprising ureolytic Bacillus sp. and non-ureolytic Bacillus cohnii was inoculated with an optimum 10% wollastonite mineral. Treated Fibres of varying dimensions (5, 10, 15 and 20 mm) and percentages (0.25, 0.5, 0.75 and 1%) were examined for their mechanical and durability properties. The inclusion of Fibres demonstrated the highest compressive strength improvement up to 26%, while the flexural and tensile features increased by 27.80% and 35%. Water absorption remained below 10%, with final absorption under 3%, confirming reduced porosity. Longer Fibres improved interlocking, minimizing abrasion loss (< 2.5 mm). Ultrasonic Pulse Velocity (UPV) exceeding 4.5 km/s and rebound number (> 40) classified the concrete as structurally dense and durable. The consistency of material integrity was substantiated by significant correlations observed between compressive strength, rebound number, and UPV. Comprehensive analyses through XRD and SEM-EDS validated extensive calcite deposition, indicating biomineralization that can contribute to autonomous crack-healing mechanisms, although self-healing efficiency was not directly quantified. These results demonstrate the viability of consortium-reinforced concrete incorporating wollastonite Fibres as a resilient and sustainability-oriented material, particularly for infrastructure applications where enhanced durability, extended service life, and reduced maintenance demands are critical.