Cracking Potential of Alkali-Activated Concrete Induced by Autogenous Shrinkage

Abstract

Alkali activated concrete (AAC) has not received broader industry acceptance, one reason of which lies in the uncertainties in the durability against shrinkage and potential cracking. Many studies reported that AAC exhibit larger autogenous shrinkage than OPC concrete. However, it is unable to deduce that AAC should show higher cracking potential than OPC concrete only based on the higher autogenous shrinkage of AAC. The cracking potential of concrete is determined by multiple factors including autogenous shrinkage, creep/relaxation, elastic modulus, and tensile properties of the concrete. However, very few studies have considered these parameters. Furthermore, the influence of precursors (e.g. slag or fly ash) on the cracking potential of AAC induced by autogenous shrinkage is also rarely studied. The aim of this study, therefore, is to investigate the autogenous shrinkage-induced cracking potential of slag and fly ash-based AAC. The free autogenous shrinkage of the specimens is measured by Autogenous Deformation Testing Machine (ADTM). The autogenous shrinkage-induced stress and cracking of the concrete under restraint condition is tracked by Thermal Stress Testing Machine (TSTM). Additionally, the influence of precursors on the autogenous shrinkage induced cracking potential is discussed.