Surface-Wave Based Technique for the Evaluation of Self-Healing Performance in Concrete

Abstract

Recently, self-healing technologies have emerged as a promising approach to extend the service life of social infrastructures in the field of concrete construction. However, evaluations of the self-healing technologies that are currently developed for cementitious materials are mostly limited to lab-scale experiments, which utilize optical microscopy techniques to detect the change in crack width due to a self-healing process, and permeability tests. Additionally, there is a universal lack of unified test methods to assess the effectiveness of self-healing technologies. Specifically, with respect to self-healing of concrete applied in actual construction, non-destructive test methods are required to avoid interrupting the use of structures. This study includes a thorough review of extant research related to theoretical backgrounds of ultrasonic test methods and case studies with respect to self-healing concrete. Additionally, the study examines the applicability and limitation of ultrasonic test methods in assessing self-healing performance of cementitious materials. The aim of this study is to develop non-destructive test methods and procedures for evaluating the performance of self-healing concrete. As the first step, an experimental investigation through a lab-scale model is performed to identify the limitations of present surface-wave technologies and research requirements to apply these technologies to self-healing concrete. In the lab-scale model tests, the effects of the course aggregate and design strength of the concrete specimen on the propagation of a surface wave are discussed. The efficiency and applicability of spectral energy based crack depth estimation methods are studied using the coefficient of determination and root mean square error analysis. A supplementary experimental study is then conducted to monitor the changes in crack size and parameters of surface wave transmission in the process of self-healing.