Feasibility study on real-scale, self-healing concrete slab by developing a smart capsules network and assessed by a plethora of advanced monitoring techniques. (20th December 2019)

• Record Type: Journal Article
• Authors: Tsangouri, Eleni; Lelon, Jordy; Minnebo, Pieter; Asaue, Hisafumi; Shiotani, Tomoki; Van Tittelboom, Kim; De Belie, Nele; Aggelis, Dimitrios G.; Van Hemelrijck, Danny
• Is Part Of: Construction & building materials. Volume 228(2019)
• Publication Date: 2019-12-20
• Subjects: Autonomous crack healing -- Concrete -- Plane capsules network -- Acoustic Emission -- Elastic Wave Tomography -- Ultrasound Pulse Velocity -- Digital Image Correlation -- Integrated monitoring system; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2019.116780
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Vascular network of macro-tubes that carries healing agent into concrete is designed. Healing feasibility tested on real-size concrete slab loaded in cycles under bending. Crack formation, agent filling and re-cracking tracked by plethora of monitoring methods. Cracks locally repair proven by pulse velocity regain after healing. Elastic wave tomography and pulse emission on drilled cores verify crack healing. Abstract: 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.