Influence of steel slag on the mechanical properties and curing time of metakaolin geopolymer

Metakaolin geopolymer (MGP) is a cementitious material which possesses attractive properties and great application potential with low carbon emission. The performance of the steel slag modified geopolymer (SSMG) is not well acknowledged. In this study, the steel slag powder was introduced into MGP as a filler to substitute part of the metakaolin powder. Then the curing process and mechanical properties of the composite SSMG were investigated. The results showed that the moist curing can ensure better SSMG mechanical properties compared to exposed curing and sealed curing. The optimum mass proportion of the steel slag powder in SSMG was 10%, its curing time was accelerated by 100% as compared to that of the MGP. In addition, the final bending strength of SSMG was increased by 8% when the final compressive strength remained unchanged compared to MGP. Moreover, micro-morphology and crystal structure of geopolymers indicated that the physical and chemical reactions existed between the active constituent of steel slag powder and the MGP base component. These reactions were beneficial to strength improvement for composite SSMG.