Abstract: The influence of water -binder ratio and slag content on the ability of sulfate resistance of mortar is studied by experiments‚and then the influence of slag addition on the ability of concrete is investigated．The results show that the ability of sulfate resistance of mortar increases only when the replacing ratio of general slag is over65％ or the ratio of slag with excitant is less than50％．By adding general slag with the replacing ratio of65％‚or slag with excitant with the replacing ratio of50％‚the ability of sulfate resistance of concrete increases．

Key words: slag, mortar, concrete, sulfate resistance