Performance study of bacteria on improving fresh, mechanical, and durability characteristics of ultra-high-performance concrete

Abstract Ultra-High-Performance Concrete (UHPC) is widely recognized due to its favorable mechanical attributes. This research aimed to evaluate the novel application of using locally grown bacteria as an additive to produce Self-Healing Ultra-High-Performance Concrete (SHUHPC). Performance study of bacteria on improving fresh, mechanical, and durability characteristics of UHPC. Promote the advancement of sustainable UHPC by using bacteria and preserving its mechanical and durability attributes and mitigating volumetric alterations. The cement content used in mixes is lower than that known in research related to UHPC. SHUHPC properties were evaluated for workability, compressive and flexural strengths, and modulus of elasticity. Durability was gauged through water permeability, sorptivity, and residual compressive strength post-exposure to high temperatures. SEM analyses confirmed the filling of pores in concrete with calcium carbonate (calcite). The most notable improvements were observed with 2.5% bacteria and 0.5% calcium lactate additions, yielding compressive strengths of 168.9 MPa at 28 days, representing a 26.04% increase compared to the reference mixture. Also, the inclusion of healing agents led to a notable reduction in water permeability by a ratio of around 22.16–29.89% lower than the control mix. Graphical abstract