Strength properties of self-compacting mortar mixed with GGBFS

Self-compacting cement grout (SCCG) is an economical and effective material used for repairing structural cracks. However, in terms of raw material cost, SCCG is higher than for conventional concrete due to the high cement volumes at relatively low water–binder ratios to achieve satisfactory combinations of high fluidity and stability. It is expected that ground-granulated blast furnace slag (GGBFS) can be used as an alternative material to replace a high volume of cement in preparing self-compacting repair mortar (SCRM). In this study, the effects of GGBFS content on both fresh and hardened properties of SCRM were investigated. The influence of different curing conditions on long-term compressive strength was also studied. In addition, the microstructure of some mixes at the age of 6 months was also observed by using scanning electron microscopy. The results show that the workability and final bleeding value of fresh SCRM decreased with the increase in GGBFS content. At early ages, the compressive strength rate of SCRM incorporating GGBFS was lower but it increased with time and became more pronounced at 30 to 50% replacement level. Thus, the maximum limit of GGBFS replacement is suggested to be controlled at 50% to make the most excellent development in long-term compressive strength. As for curing conditions, specimens stored in water showed higher gain in long-term strength than those samples exposed to air and natural weather weathering conditions.