Mortar-mini -vascular networks filled with nanolimes: An innovative biomimetic approach for enhancing resilience in built heritage

Climate change is increasingly exposing our built heritage to a wider range of extreme hazards. In response to these challenges, it is crucial for historic masonry repair technologies to adapt and promote a resilient preservation strategy that can withstand long-term impacts. Inspired by biomimetic technologies, this research introduces the use of 4D-printed mortar-mini vascular networks (m-MVNs) for repairing cracks in lime-based mortars. m-MVNs consist of interconnected channels- made from polylactide acid (PLA) – designed to fit completely within the mortar joint. The study explored the properties of tailored nanolime dispersions as healing agents. Two different blends were studied with varying alcohol/water ratios, specifically 10 g/L of calcium hydroxide in either a 50:50 or 80:20 water:ethanol mixture. Specimens were pre-cracked at different ages (28–196 days) and three levels of damage (70 % of the compression strength in pre-peak regime; 90 % of the compression strength in post and pre-peak regime) and then healed for 14 days. Some self-healing ability was observed in the plain lime samples, with enhanced performance in samples containing empty m-MVNs. m-MVNs filled with nanolime demonstrated strong healing performance, with the 50:50 dispersion being the most promising, achieving a ceiling healing index of 37 % in strength and 53 % in stiffness.