Surface and through transmission dispersion ultrasonic characterization of expansive durability attacks in concrete

The durability of concrete is substantially reduced by chemical and physical expansive degradation mechanisms. The degradation of the material depends on the mechanism and the intensity of the attack. However, they usually produce internal stresses, that eventually evolve into cracking, and a reduction in stiffness. The degradation mechanisms that will be studied are chemical sulfate attack, biogenic sulfuric acid attack, alkali-silica reaction, freeze-thaw, and combinations. Early detection, and identification of the durability attack results in a reduction of the cost of repair, and environmental impact. Elastic wave-based nondestructive techniques are sensitive to changes in the mechanical properties of the material, however, single-frequency ultrasound pulse has shown low sensitivity to these mechanisms. This research intends to use a multifrequency dispersion analysis based on surface, and through transmission ultrasound for early detection, characterization of expansive durability attacks, and elastic wave-based differentiation. In addition, a non-contact methodology will be investigated, this will allow for automatized scanning. And finally, acoustic emission will be employed for the first time to assess, and characterize the negative consequences of expansive durability attacks in concretes fracture behavior, as well as a passive characterization of negative bacterial activity present in the biogenic sulfate attack, such as biodeterioration