2016 AAAS Annual Meeting (February 11-15, 2016)

February 10 - 15, 2016

Smart Materials for Sustainable Infrastructure: Self-Healing Concrete and Asphalt

Bridges, tunnels, and roads: much of the world's critical infrastructure is composed of concrete and asphalt. Cracks let in water and salt, threatening steel reinforcement vulnerable to corrosion. Water ingress leads to further damage during freeze-thaw cycles. Repair work, complex and time-consuming, causes traffic jams. Concrete and asphalt with self-healing capabilities offer a solution to this ubiquitous challenge. This symposium discusses the design of smart materials with self-healing properties. For example, early-stage cracks in concrete can be sealed by micro-encapsulated calcium carbonate-precipitating bacteria – which remain dormant until cracks appear. Superabsorbent polymers can be applied that expand on contact with water. For cracks under dynamic load, an elastic polymer can be stored in microcapsules; when cracks begin to propagate, the capsules break to release it. Self-healing has also been demonstrated in a new type of asphalt that incorporates steel fibers, allowing inductive heating to melt bitumen and flow into cracks. The session addresses validation of healing efficiency, which is essential for new construction deploying novel materials. Evaluations of various non-destructive testing techniques have shown promising results. Methods such as acoustic emission analysis and time-of-flight ultrasound techniques have the potential to observe the activation of healants and to monitor the restoration of material properties in real structures.