Anti-crack performance of concrete with phosphorus slag and fly ash singly and compositely added is investigated in terms of physical performance, hydration heat, dry shrinkage and creep. Index K is introduced to evaluate the crack resistance of phosphorus slag concrete. Results show that the strength of phos-phorus slag concrete increases with the increase of fineness, and when surface specific area is greater than 300 m2/kg, the tendency slows down. Strength decreases with phosphorus slag content increasing and there is an optimal content existing between 30% and 50%. Both phosphorus slag and fly ash have obvious effect on elongating time setting, reducing hydration heat to a large extent and increasing creep value. Crack resistance of phosphorus slag concrete is divided into three stages, namely early hazardous stage, growth stage and later mature stage. With microstructure analysis, mechanism of effect of phosphorus slag on concrete performances and P and F on cement hydration is explored. It is concluded after comprehensive evaluation that the crack resistance of phosphorus slag concrete is approximate to, even to some extent better than that of fly ash concrete.
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