Bacteria-based self-healing concrete exposed to frost salt scaling

Abstract

Self-healing concrete is an innovative and promising technology to increase the durability and service life of the structure by limiting the influence of aggressive attacks. However, knowledge on the performance in realistic conditions is limited. This paper presents the benefits of introducing a bacteria-based healing agent in concrete to enable self-healing, assessed under frost salt scaling conditions. Durability tests such as scaling, water permeability and chloride ingress were performed. In addition, a microstructural analysis was realized based on mercury intrusion porosimetry (MIP), fluorescence microscopy, thin section analysis, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy. The bacteria enhanced the concrete properties, resulting in a 90% higher frost salt scaling resistance than the reference concrete and reduced chloride penetration by 46%. The bacteria-based concrete furthermore showed fewer microcracks. However, chloride penetration through cracks could not be prevented since only partial crack healing was achieved for the studied mix design.