Nondestructive Evaluation of Autonomic Crack Healing in Concrete Using Ultrasonic Wave Propagation

Abstract

Cracks in concrete structures are unavoidable, resulting in the deterioration of concrete structures. An effective way to heal cracks, integrated with a suitable monitoring method, is of great significance. This research explores and demonstrates the autonomic healing and simultaneous ultrasonic monitoring of thin cracks using silica-based chemical agents. The sensitivity of ultrasonic waves to the change in the elastic properties of the medium through which it propagates is used to monitor the progressive healing of cracks in concrete. An increase in the ultrasonic pulse transmission (UPT) signal strength with the progression of healing in cracked concrete was used to interpret the condition of the crack. The ultrasonic results were validated by visual observations, an increase in compressive strength and a reduction in water permeability. Further, the efficacy of silica-based chemical healing agents in crack-healing concrete was also verified by microstructural scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) tests. The study successfully demonstrates the efficacy of sodium silicate as an effective chemical healing agent in cementitious materials, with the healing process well picked up by ultrasonic pulse transmission measurements. © 2024 American Society of Civil Engineers.