Effect of blended steel slag–GBFS mineral admixture on hydration and strength of cement

The possibility of using steel slag and granulated blast furnace slag (GBFS) as a blended mineral admixture for concrete is investigated. The results show that GBFS can weaken the negative effects of steel slag on the properties of concrete, such as decrease of the strength and introduction of harmful pores. The steel slag–GBFS blended mineral admixture containing 30–50% steel slag can enable the mortar to have a satisfactory strength. Steel slag has an excellent ability to retard the setting time, decrease hydration heat, and improve the fluidity of concrete comparing with GBFS. The blended mineral admixture composed of 50% steel slag and 50% GBFS is more efficient than fly ash in decreasing the early hydration heat of binder. Steel slag and GBFS are mutually complementary in many properties, and an ideal blended mineral admixture which endows the concrete satisfactory strength, long setting time, low hydration heat, and good fluidity can be obtained by mixing steel slag and GBFS at proper ratios.