Enhanced autogenous healing of ground granulated blast furnace slag blended cements and mortars

Abstract

In this study, the autogenous healing characteristics of cementitious materials with ground granulated blast furnace slag (GGBFS) and crystalline admixtures were investigated. The main variables were the replacement of cement by GGBFS (15–50%) and crystalline admixture types (anhydrite, Na2SO4, and Na2CO3). Isothermal calorimetry analysis was performed to evaluate the potential for crack self-healing. The water flow test was used to evaluate the autogenous healing performance after inducing cracks in 7-day aged specimens. The autogenous healing products were analyzed through scanning electron microscopy (SEM). Cumulative heat was the highest when the GGBFS replacement percentage was 15% and the crystalline admixtures were used simultaneously, and it decreased when the replacement percentage of GGBFS increased. The results of the water flow test showed that crack self-healing performance was enhanced as the replacement ratio of GGBFS was increased up to 30%. The crack self-healing performance was the highest when anhydrite and Na2SO4 were used at the same time. SEM analysis showed that the types of self-healing products affected the crack self-healing performance. Keywords: Autogenous healing, Water flow test, Isothermal calorimetry, Ground granulated blast furnace slag, Crystalline admixture