Effects of the type of activator on the self-healing ability of fiber-reinforced alkali-activated slag-based composites at an early age

Abstract

This paper presents an experimental investigation of the self-healing ability of fiber-reinforced slag-based composites activated by a single type of alkali activator at an early age. In order to investigate the effects of the type of alkali activator on the self-healing ability of fiber-reinforced slag-based composites, three mixtures reinforced by polyethylene fibers and with different alkali activators, in this case calcium hydroxide, sodium hydroxide, and sodium silicate, were designed and prepared. Compressive strength and uniaxial tension tests were conducted to measure the mechanical properties of each mixture. The self-healing ability in each case was evaluated by observing the crack width and by measuring the resonance frequency. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were also utilized to analyze the morphology and chemical compositions of the healing materials. The results of these tests showed that autogenous healing of alkali-activated slag-based composites is accomplishable through structural restoration, specifically by reducing the crack opening and through mechanical recovery. The dominant healing materials of the calcium activator-based alkali-activated slag composite was CaCO3, in contract to the C-(N)-A-S-H, CaCO3, and some amount of Na2CO3 which formed in the sodium activator-based alkali-activated slag composites.