Fiber-Matrix Bond Characteristics of Alkali-Activated Slag Cement-Based Composites

Fiber-matrix bond properties of alkali-activated slag cements (AASC)-based composites have not been studied comprehensively in literature. Within the scope of this study, the effects of AASC matrix phase composition and the silicate modulus of activator solution on the pullout behavior of steel fiber were investigated under water- and steam-curing conditions. Test results showed that AASC have a superior bond strength compared to portland cement (PC). Bond strength of AASC mortars with a compressive strength greater than 18MPa were found higher than that of PC mortar with a compressive strength of 55MPa. When the compressive strength of AASCs is higher than 40MPa, the bond strength of AASC exceeds the bond strength of PC mortars that have compressive strength of 120MPa. Microstructural analysis revealed that the map cracking in the fiber-matrix transition zone, which was induced by high drying shrinkage of AASC, can be eliminated by incorporating pozzolans. Consequently, it is possible to produce much higher-performance fiber-reinforced composites by using AASC owing to its superior adherence to steel fiber. (C) 2016 American Society of Civil Engineers