Self-healing concrete full-scale site trials

The development of a self-healing concrete aimed at improving the durability of concrete structures has been the focus of Materials for Life (M4L), a 3 year research project conducted by the universities of Cardiff, Bath and Cambridge. This interdisciplinary research has culminated in the UK’s first site trial of self-healing concrete on the A465 Heads of the Valleys section two project in South Wales hosted by one of the main industrial sponsors Costain Group Plc. The trial, which follows on from a series of small-scale laboratory experiments, comprises a number of concrete wall panels which contain combinations of the self-healing techniques studied during the project. These techniques include (i) encapsulation of healing agents led by Cambridge University, (ii) healing via bacterial action led by Bath University, and (iii) the use of shape memory polymer (SMP) based systems for crack closure and delivery of healing agents through vascular flow networks by Cardiff University. This paper presents the design, methodology and initial results of the site trial. The degree of self-healing is quantified via visual measurements of the crack aperture. An insight is offered into which of the combinations of techniques has shown the most promise for a self-healing concrete solution for use within the construction industry. At a later stage of the project the regain in mechanical load and stiffness after damage and the reduction in permeability compared to that of the damaged concrete will also be assessed.