Self-Healing of SMA and Steel-Reinforced Mortar with Microcapsules

Abstract

Healing capabilities of shape-memory alloys (SMAs) and steel-reinforced mortar with self-healing microcapsules were investigated. Small cracks ranging from 13 to 152 μm were induced by three-point bending, and specimens were subjected to a 14-day healing period under water-submerged conditions at 55°C±5°C to induce shape-memory effect activation. Light microscopy investigation was performed at 3, 7, and 14 days of the healing period. Moreover, healing products were investigated using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Healing efficiency improvements with the increase in microcapsule content were reported at 3 and 7 days for steel-reinforced specimens. Furthermore, for all mortar mixes evaluated, SMA-reinforced specimens exhibited a superior healing performance than steel-reinforced specimens at 3 days of healing due the crack-closing action of SMA. The overwhelming majority of healing products were identified as likely calcite crystals, and the limited gellike products also present were presumably calcium silicate hydrate (C─ S─ H).