Chitosan Shrinking Fibers for Curing-Initiated Stressing to Enhance Concrete Durability

Concrete, a widely used construction material, faces environmental concerns and limited durability. This study aimed to enhance concrete durability and long-term resilience by incorporating shrinking chitosan-based fibers. Two types of fibers were used: active fibers, which shrink upon initiation of the curing cycle in concrete, and passive fibers, which served as experimental controls and were pre-shrunk before being added. Two types of durability tests were conducted: freeze-thaw and chloride penetration. Fiber ratios of 0.5 wt%, 1 wt%, and 2 wt%, along with a 0 wt% control, were used for freeze-thaw testing, while ratios of 0.24 wt%, 0.36 wt%, 0.5 wt%, 1 wt%, and 2 wt% were used for chloride penetration. Results demonstrated significant durability improvements with active fibers. Active fiber-reinforced concrete exhibited over 200% greater freeze-thaw durability than passive fibers and over 500% compared to non-reinforced concrete. Chloride penetration testing revealed reduced penetration rates in active fiber concrete. After saltwater exposure, active fiber-reinforced concrete showed up to 59% higher resistance than passive fibers and 249% compared to the control group. These findings highlight the potential of chitosan fibers to significantly enhance concrete durability, paving the way for more sustainable construction practices.