Enhanced fracture and durability resilience using bio-intriggered sisal fibers in concrete

Abstract

Biomimetic agents and natural fibers are the promising combo to enhance the strength and self-healing efficacy of concrete infrastructures. However, their contribution in durability and fracture attributes of the host concrete matrix is still questionable. This study explores the use of sisal fiber reinforcement and Bacillus Subtilis to modify the fracture, shrinkage, and durability performance of concrete. Fracture response was analyzed in compression, tension and flexural followed by durability tests conducted for chloride penetration, water absorption, and acid resistance. Results revealed that the addition of Bacillus Subtilis increases stiffness, while sisal fiber imparts ductility to the concrete. The resulting mixture exhibited significant improvements in compressive strength (14.0%), split tensile strength (36.8%), flexural strength (30.9%), and bi-surface shear strength (25.4%) as compared to the control mixture. Additionally, the toughness indices of the resulting concrete improved under compressive, split tensile, and flexural loadings. Incorporating sisal fiber and Bacillus Subtilis into concrete mixtures also led to a notable reduction in linear shrinkage (58.9%), attributed primarily to the fiber-reinforcing effect. When sisal fiber and Bacillus Subtilis are combined in the concrete mix, there is a net improvement in the concrete's durability. The resulting blend exhibited an increase of 18.3%, 24%, and 14.1% in resistance to water absorption, chloride ion penetration depth, and acid attack, respectively, as compared to the control mixture. Micro-forensics endorsed the signatures of microbially-induced calcite precipitation in the concrete mixture, which contributed to add in the durability of the resulting matrix. The study demonstrated that the conjunctive use of Bacillus Subtilis and sisal fiber can yield durable and ductile concrete. The findings provide valuable insights into the use of biomimetic agents and natural fibers to enhance concrete fracture and durability attributes, with significant potential for practical applications in the construction industry.