Crack sensing and healing in concrete beams based on wire-crack sensors and healing tube

This paper summarizes a study of a low-cost device capable of crack sensing and healing intended for smart concrete developments. Crack sensing capability of the device was achieved via a wire-crack sensor, while healing of concrete cracks was realized through an embedded healing tube containing a copolymer adhesive which was released following fracture of the tube. Initial results obtained from a series of four-point bend tests of two-meter reinforced concrete beams were encouraging - the results of the tests demonstrated the capability of the externally-mounted and embedded wire-crack sensors in detecting crack widths as small as 0.18 mm and 0.96 mm, respectively. In addition, the study also described the use of a simple resistive circuit connected to the wire-crack sensor rendering it possible to identify the location of the crack zones in the concrete beam accurately by monitoring only a single channel of the resistive circuit. The spatial resolution (i.e. crack location resolution) and the sensing length of the wire-crack sensor could be readily adjusted to suit the requirements of the monitoring application. When the wire-crack sensor was integrated to the healing tube and then embedded in the host structure, the assembled device was tested and shown to be able to successfully detect, locate and heal the cracks in reinforced concrete beams.