Regenerative cementitious skins: A novel self-healing overlay approach for enhanced durability

Abstract

This research presents a novel, sustainable approach to extending the lifespan and durability of concrete structures using regenerative, thin-layered, self-healing engineered cementitious composites (ECC) applied as surface skins. By targeting only exposed areas where damage typically initiates, these thin-layer applications minimise material usage and reduce overall maintenance costs, offering an innovative and cost-effective solution for both new constructions and retrofitting existing structures. This study investigates the healing efficiency of ECC skins of varying thicknesses (0, 5, 10, and 20 mm), with durability assessments including water permeability and rapid chloride migration tests. Surface crack recovery is further analysed using optical and scanning electron microscopy (SEM) to capture healing over time. Results show that a 10 mm skin achieves up to 95 % healing, while a 20 mm skin achieves complete healing within the six-month conditioned healing period. Compared with conventional full-thickness ECC applications reported in the literature, these skins reduce the amount of healing agents required by up to 60 % while maintaining comparable healing performance. This study highlights the potential of regenerative cementitious skins as an innovative and sustainable self-healing solution, suitable for both new builds and the repair of existing structures, with significant reductions in material use and costs compared to typical ECC applications. This approach opens new horizons for rapid repair applications and efficient methods, particularly effective for hard-to-reach areas, including bridges, tunnels, and marine structures through robotic spraying or automated trowelling, enabling quick deployment for large-scale maintenance and emergency repairs. • Development of novel ECC self-healing regenerative skins to enhance concrete durability. • Water permeability tests show full healing for 20 mm skins and 95 % for 10 mm skins. • RCM tests show 28 % healing for 20 mm skins and 17 % for 10 mm ECC skins. • SEM, ICS, and image analysis confirm healing products and growth with skin thickness. • ECC skins achieve comparable healing with 60 % less healing agent than full-depth layers.