氟石膏基材料胶凝性能和浸出毒性

Leaching Toxicity and Cementitious Properties of Fluorgypsum-based Binder

利用矿渣和少量熟料对氟石膏进行改性,制备出一种高氟石膏掺量的氟石膏基水硬性胶凝材料,研究了氟石膏基水硬性胶凝材料胶凝性能和胶砂块浸出液毒性,并通过XRD、FT-IR和SEM对净浆试件进行微观分析。结果表明:氟石膏含量60%~70%、矿渣含量25%~35%和熟料含量5%并外掺1%K_2SO_4混合而成胶凝材料,性能好并具有低浸出毒性,其3 d和28 d胶砂抗折抗压强度均达到GB 175-2007中复合硅酸盐水泥32.5级水泥强度指标,软化系数始终保持在0.80以上,胶砂块浸出液氟离子浓度和pH值均较低,密实的微观结构体是胶砂块浸出毒性低主要原因。

By modifying fluorgypsum with blast furnace slag and a small amount of clinker, the fluorgypsum-based hydraulic cementitious binder with high fluorgypsum amount were prepared. Leaching toxicity and cementitious properties of fluorgypsum-based binder were evaluated. Hydration products and microstructure analysis of paste specimens were carried out through XRD, FT-IR and SEM. The results showed that the mixture with 60%-70% fluorgypsum, 25%-35% blast furnace slag, 5% clinker and K2SO4 at 1% relative to the cementitious material （FBHB） had the fine cementitious properties and the lower leaching toxicity. The flexural and compressive strengths of FBHB2 mortars specimens reached the guide line of compound silicate cement grade 32.5 of GB 175-2007 in 3 and 28 days. Moreover, these softening coefficient always keep above 0.80. Fluoride concentration and pH value of leaching liquid of mortars specimens were lower, the compacted microstructure formation was the main reason for lower leaching toxicity of mortars specimens with FBHB.