Effect and mechanism of activation of activator to fluorgypsum

strength

softening coefficient and leaching toxicity of composite cementitious material are studied. Through activation testing of NaOH

Na2SO4 and NaF

the optimum adding quantity was defined as 1%. On the basis of it

80% fluorgypsum was further processed to improve its quality with slag

fly ash and clinker. With 1% Na2SO4

25% slag

5% fly ash and 89% fluorgypsum

the cementitious material properties were excellent; the 28-day compressive strength could reach 12.25 MPa; the softening coefficient was 0.70; and the concentration of fluoride could be reduced to 0.7485 mg/L. The analysis of SEM and XRD show that gypsum

a few calcium silicate hydrate

ettringite and calcium fluoride are filled and packed each other

which hampers water enter particle structures

increases the water resistance of cementitious material and reduces leaching toxicity of cementitious material.