Damage detection and healing performance monitoring using embedded piezoelectric transducers in large-scale concrete structures

Abstract

Concrete keeps being the leading structural material due to its low production cost and its great structural design flexibility. However, concrete is prone to various ambient and operational loads which are responsible for crack initiation and extension, leading to decrease of its anticipated operational service life. The current study is focusing on the use of ultrasonic wave propagation techniques based on low-cost and aggregate-size embedded piezoelectric transducers for the online monitoring of the damage state and the healing performance in concrete structures with an autonomous healing system in the form of encapsulated polyurethane-based healing agent embedded in the matrix of concrete. The crack formation triggers the autonomous healing mechanism which promises material recovery and extension of the operational service life. The proposed technique is applied on large-scale, steel reinforced, concrete beams (150mm × 250 mm × 3000 mm), subjected to four-point bending. After the capsules are broken and the healing agent is released, which results in filling of the crack void, and polymerized, the concrete beams are reloaded. The results demonstrate the ability of the monitoring system to detect the initiation and propagation of the cracking as well as to assess the performance of the self-healing system