Abstract: As a new cementing material,geopolymer has a broad application prospect,and the preparation of geopolymer from nickel slag is of great significance to realize the comprehensive utilization of solid waste.Nickel slag and fly ash based polymer was prepared by activation of sodium silicate and sodium hydroxide composite alkali solution.The effect of fly ash content on the mechanical properties,antifreezing properties and antiseawater erosion properties of geopolymer was discussed,and the changing rules were expounded by means of XRD,SEM and pore structure analysis.The results showed that:① the strength of geopolymer is improved by the introduction of fly ash.When the fly ash content is 10%,the mechanical properties are optimal,and the 7 and 28 d compressive strengths are 37.2 MPa and 42.5 MPa,respectively,which are increased by 21.97% and 17.40% compared with the blank group.② Proper incorporation of fly ash can further reduce the compressive strength loss and mass loss of geopolymer in freezethaw cycle and drywet cycle.When 10% fly ash is added,the compressive strength loss rate and mass loss rate of the sample after 50 freezethaw cycles are 24.7% and 14.9%,respectively,and the compressive strength loss rate after 50 wetdry cycles is 21.5%.③ Fly ash is beneficial to alkali excited reaction and increases reaction products.At the same time,the smaller particle size of fly ash provides a better filling effect on geopolymer.The results can provide reference for the development of nickel slagfly ash base polymer and the exploration of related durability problems.

Key words: fly ash,nickel slag,geopolymer,durability properties,microstructure