Investigation on the Potential of Bacteria‐Coated Jute Fiber for Enhancing Mechanical Properties and Self‐Healing Capabilities in Concrete

Concrete faces challenges such as low tensile strength, susceptibility to cracking, and limited self‐healing capabilities. To address these issues, natural fibers have gained attention as reinforcements due to their high specific strength, stiffness, biodegradability, and renewability. Even with these advantages, natural fibers exhibit high water absorption, leading to dimensional instability and affecting the mechanical properties of concrete. This study investigates the impact of Bacillus amyloliquefaciens bacteria–coated jute fiber (BABCJF) on the performance of concrete, aiming to enhance its mechanical properties and self‐healing capabilities. In contrast to prior research that directly mixed bacteria into concrete, this study uses jute fibers coated with B. amyloliquefaciens to improve mechanical properties and self‐healing performance. The mix design was prepared according to the American Concrete Institute (ACI) mixing procedure, incorporating 0.5%, 1.0%, and 1.5% of BABCJF and 1.0% uncoated jute fiber in concrete mix. Mechanical and self‐healing property tests were performed after the age of 7, 14, and 28 days in water. The results demonstrated concrete mix with the addition of 1.0% BABCJF exhibited the highest flexural and compressive strength improvements, with a compressive relative strength gain of 19.9%, 42.0%, and 17.6% at age of 7, 14, and 28 days. Other concrete mixes with BABCJF have also enhanced the mechanical strength of concrete. However, concrete mix with 1% uncoated‐jute fiber decreased the compressive strength of concrete even if it had upgraded the flexural strength of concrete. From the three‐dimensional optical microscope analysis, it has been shown that the enhancement of mechanical strength in B. amyloliquefaciens bacteria–coated reinforced concrete is due to the formation of larger amounts of calcium carbonate precipitates filling the cracks and coating the surface of the jute fiber which in turn reduced the water absorption rate of the jute fiber and created a strong bond of fiber with the concrete matrix.