Inspection, maintenance and repair of reinforced concrete structures are time consuming and costly, and many structures are difficult to access. The EU-funded HEALCON (Self-healing concrete to create durable and sustainable concrete structures) project addressed these problems by developing novel self-healing concrete. It focused on early-age cracks and those due to mechanical loading or bending where self-healing concrete could have the greatest impact. The team used inelastic limestone precipitation by bacteria and smart hydrogels to create water tightness, and identified spores that discourage corrosion. The bacteria have been successfully incorporated into expanded clay particles or have been added to the concrete as self-encapsulated mixed cultures. In addition, HEALCON developed encapsulated polymers to overcome bending cracks due to dynamic loading. It optimised the use of glass-encapsulated commercial polyurethane-based polymer precursors, investigated encapsulation in polymeric spherical capsules and worked on increasing durability during mechanical mixing. Materials and processes were validated with computer models and non-destructive testing (NDT). Simulations of both the fracture and healing processes have provided insight regarding the most important parameters which affect self-healing. Three-point bending tests on concrete beams containing encapsulated polyurethane demonstrated the ability of several different NDT techniques to quantify self-healing. Concrete remains one of the most important building materials and yet it has not changed substantially to reflect new technologies. HEALCON has made an important contribution to the fate of the future European infrastructure with the development of self-healing concrete. The results were discussed in a final project conference held in November 2016 and in a video presentation available on the project website. The technology will undoubtedly enhance longevity while decreasing the complexity, time and cost associated with inspection, maintenance and repair.
Self-healing concrete, concrete structures, HEALCON, bacteria hydrogels, encapsulated polymers