Feasibility study on real-scale, self-healing concrete slab by developing a smart capsules network and assessed by a plethora of advanced monitoring techniques

摘要

The study presents the design, manufacturing and testing of the first concrete structural element that carries a plane network of long, brittle macro-capsules into which chemical repair agent circulates to provide autonomous and repeatable healing of formed cracks under service loads. The vascular network design emerges as the most promising concept based on a decade of research, the milestones of which are briefly reported. In this experimental attempt, the network of simultaneously occurring and interacting cracks formed on a real-scale steel reinforced concrete slab loaded under four-point bending are tracked by an integrated sensing configuration that combines advanced acoustic monitoring techniques (Acoustic Emission, Elastic Wave Tomography, Ultrasound Pulse Velocity measurements) with Digital Image Correlation and visual crack inspection. Macro-capsules rupture is depicted by AE monitoring of high energy burst signals. It is shown that effective healing occurs locally, detected by sealing of open cracks and regain in mechanical properties. Indicatively, pulse velocity regain up to 100% is detected on healed zones, result also obtained by elastic wave tomography. Limited repair is measured on cracks with openings larger than 0.5 mm. This outcome could only be verified by correlating the experimental evidence of different monitoring methods, highlighting the need for design optimization and establishment of an advanced tempo-spatial structural health monitoring protocol. (C) 2019 Elsevier Ltd. All rights reserved.