A bio-polymeric strategy for enhancing the strength, durability of concrete and shrinkage reduction

The formation of cracks in concrete is inevitable and often accelerated by inadequate curing. In many regions, the availability of potable water for external curing is limited, leading to improper curing practices and the development of shrinkage cracks. Resolving this issue is essential to enhancing concrete structures' long-term performance. In the present study, an alternative approach has been explored to reduce reliance on external curing while enhancing the mechanical and durability properties of concrete. Superabsorbent polymer (SAP) was used as an internal curing agent, and a bacterial self-healing mechanism was employed to mitigate cracks and refine the pore structure of concrete. Four different mixes were prepared for investigation: a control mix, a mix containing SAP, a bacterial concrete mix, and a mix incorporating both superabsorbent polymer and bacteria. A series of tests, including shrinkage, compressive strength, flexural strength, and electrical resistivity, were conducted to evaluate the performance of these mixes. The experimental results confirmed that the inclusion of superabsorbent polymer significantly reduced shrinkage, while the combined use of superabsorbent polymer and bacteria further enhanced the properties of concrete. The combination of superabsorbent polymer and healing agent exhibits a 15.1% and 26.4% improvement in compressive strength in comparison with the control mix at an age of 7 and 28 days. A strong correlation was observed between compressive strength and shrinkage, indicating that reduced shrinkage contributes to improved concrete performance. This study shows that combining superabsorbent polymer and bacterial self-healing offers an effective way to overcome curing challenges and enhance the strength and durability of concrete, especially in water-scarce regions.