Abstract Inspired by vascular systems in Nature and root canal techniques in dentistry, this study proposes a externally assisted bio-inspired repair strategy for aged concrete. Artificial channels (like arteries) are created from the surface of cementitious composites via micro-drilling and connected to existing subsurface crack networks, forming a vascular-like system capable of providing controllable repair by delivering healing agents to damaged regions. Healing agents composed of agar biopolymer and L. sphaericus bacteria are injected through the created vasculature to initiate microbially induced calcium carbonate precipitation (MICCP). Experimental results confirm that the biological agents can be delivered effectively through artificial vasculature to subsurface crack location with the help of drilled channel and provides higher amount of biological calcium carbonate precipitation in the crack area compared to non-drilled samples. Additionally, the effect of drilled vasculature on mechanical performance of concrete due to concrete material removal is evaluated. The mechanical impact of drilling is found to be manageable by controlling drilling dimension, specimen dimension, aggregates size, drilling types and channel design which suggests that the creation of vasculature leads to controllable mechanical effects on the cementitious composites. The effect of the drilled channel on the fracture pattern is also simulated using phase-field modeling and verified with experimental results. Furthermore, the analysis on MICCP media delivery is conducted by dynamic rheometer, light microscopy, image processing and thermogravimetric techniques. These methodologies are used to examine the transport dynamics of the biological healing agents and to quantify their integration depth inside the crack volume. The findings of this study reveal that creation of engineered drilling channel in aged concrete can deliver healing agents in the desired region of interest without significant human intervention which enhances MICCP-based controlled crack healing.
Iqbal et al. (Mon,) studied this question.