Development and Testing of Vascular Networks for Self-Healing Cementitious Materials

Abstract

The success of self-healing cementitious materials relies on their ability to repeatedly heal over the lifetime of the material. Vascular networks have a distinct advantage over other self-healing techniques whereby the healing agent in the network can be routinely replenished. The aim of this study was to develop a multi-use vascular network that can be re-used over the lifetime of a structure, to enable repeated self-healing events in cementitious materials. The feasibility and self-healing efficacy of novel 2D vascular networks in concrete beams were tested on laboratory-scale specimens before being trialled in-situ on larger, structural-scale elements. The vascular networks were formed via linear interconnecting hollow channels filled with a healing agent which is delivered to zones of damage under an externally supplied pressure. This technique was reproducible at large scale and channels were re-filled over a test period of 6 months. Of the two healing agents used in this study, sodium silicate (SS) proved easier to handle and supply into the vascular network, but cyanoacrylate (CA) offered greater strength recovery (up to 90%) in a relatively short timescale. The presence of flow networks in the cover concrete tended to act as a crack initiator and this was particularly evident in the larger scale specimens. Nevertheless, the potential to enhance and enable multi-scale healing in cementitious materials has been demonstrated.