Autogenous healing of high strength engineered cementitious composites (ECC) using calcium-containing binders

•Mechanical properties of ECCs using calcium-containing binders were investigated.•Crack area reduction was visualized through an image processing technique.•Robustness of healing materials was assessed by healing patterns and tensile behavior.•Healing materials were characterized by SEM/EDS. This paper presents an experimental investigation of autogenous healing of engineered cementitious composites (ECC) with compressive strength over 90 MPa and tensile strain capacity over 4.5% using different amounts of calcium-containing binders, i.e., Portland cement, CaO-based expansive agent (CEA), and ground granulated blast-furnace slag (GGBS). Polyethylene fiber was used as a reinforcing fiber to manufacture high strength ECC. Compressive strength and uniaxial tension tests were performed to evaluate the mechanical properties of ECC at 28 days of age. A series of experiments including crack area reduction, resonant frequency recovery, and tensile behavior before and after the healing process was performed to comprehensively assess the autogenous healing characteristics and mechanical restoration of ECC. It was possible to detect and analyze the healing materials formed within the cracks by scanning electron microscopy and energy-dispersive X-ray spectroscopy, respectively. The test results showed that autogenous healing characteristics such as crack sealing, stiffness recovery, and types of healing materials depended on the different amounts of calcium-containing binders. It was also observed that, instead of enlarging old cracks after the healing process, the ECC itself can create new microcracks.