Microfibre-reinforced cementitious materials for preventive concrete pavement crack repair: Balancing extrusion-based crack-filling with mechanical performance

Preventative repair of cracked concrete pavements requires materials that balance effective extrusion and crack-filling with high mechanical performance. Here, we present a polyvinyl alcohol microfibre (PVAF)-reinforced commercial belitic calcium sulphoaluminate mortar, engineered with this balance. A fresh mix of the mortar plus 1% (w/w) of a water reducer and up to 0.6% (v/v) of short (∼1–2 mm) PVAF could be extruded and fill cracks 6 mm wide. Cracked concrete specimens repaired with this material under flexural loading exhibited a 30% increase in ultimate strength and twice the modulus, strain at failure, toughness and residual strength compared to plain RS. Under slant shear loading, repaired specimens demonstrated a modest increase in slant shear strength. These enhancements are attributed to fibre-induced crack bridging within the repair materials and reduced stress concentration at the repair interfaces. To accelerate material development, we implemented a rapid real-to-simulation workflow that reduced the crack-filling screening time for a material from several hours to less than one hour.