Abstract: Nickel slag is theindustrial solid waste discharged during the nickel production. Using nickel slag as a raw material to prepare geopolymers not only reduces the carbon footprint of geopolymers,but also promotes the sustainable development of the nickel-iron alloy industry. In this paper,nickel slag wasincorporated into the fly ash-based geopolymers,and the influences of the slag addition on the shrinkage behavior of the binders were investigated. The results showed that the 25% nickel slag addition not only improved the compressive strengths of the geopolymers,but alsoreduced the autogenous shrinkage and drying shrinkage ratios. Nickel slag exhibitedrelatively lower reactivity than fly ash. The addition into fly ash-based geopolymers slowed down the kinetics of alkali-induced reaction,and consequently mitigated the self-shrinkage of the binders. On the other hand,nickel slag particles played themicro-aggregate role in the binders. The pore structure of geopolymers was compacted. It not only enhanced the compressive strengths of the binders,but also restricted the water evaporation during the drying process and consequently reduced the drying shrinkage.

Key words: geopolymer,nickel slag,shrinkage,compressive strength,pore structure