同等P2O5掺量下,不同石膏对超硫酸盐水泥水化机理的影响

Effects of Gypsum with Same Content of P_2O_5 on Hydration Mechanism of Supersulphated Cement

研究了同等P_2O_5掺量下的磷石膏、硬石膏和二水石膏对超硫酸盐水泥(SSC)水化机理的影响,其中硬石膏与二水石膏中的P_2O_5以可溶性分析纯P_2O_5形式掺入。测试了3个系列SSC净浆试件各龄期抗压强度和孔溶液p H值,对比了其早期水化放热过程的差异,采用XRD、SEM分析了其水化产物相及微观形貌。结果表明:外掺分析纯P_2O_5的硬石膏基和二水石膏基SSC各龄期抗压强度与孔溶液p H值接近;与磷石膏基SSC相比,外掺分析纯P_2O_5的硬石膏与二水石膏降低了SSC各龄期孔溶液p H值,对SSC早期强度发展有所减缓,明显促进了后期强度的发展;早期水化放热分析结果显示,外掺分析纯P_2O_5的硬石膏与二水石膏加快了SSC第二放热峰的出现,缩短了凝结时间;XRD和SEM结果表明,外掺分析纯P_2O_5的硬石膏与二水石膏对SSC的激发效果比磷石膏更好,用其制备的SSC浆体后期形成了更多更密实的水化硅酸钙与钙矾石。

The effects of phosphogypsum, anhydrite and dihydrate gypsum with same content of P2O5 on hydration mechanism of supersulphated cement （SSC） were investigated, the P2O5 of anhydrite and dihydrate gypsum were incorporated by solubility and analytical pure P2O5. The compressive strength and pore solution pH value in various age of three series of SSC specimens were tested. And the differences of early hydration exothermic process were compared. The hydration products and microstructure were analyzed by XRD and SEM. Results show that compressive strength and pore solution pH value in various age of anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 based SSC specimens are close together. Comparing with phosphogypsum based SSC, anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 decrease the pore solution pH value in various age of SSC. And they slow down the early strength development of SSC, but obviously promote the long-term strength development of SSC. The exothermic analysis show that anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 quicken the appearance of the second exothermic peak of SSC, and shorten the setting time of SSC. XRD and SEM analysis show that anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 have a better activation effect than phosphogypsum on SSC, SSC paste with anhydrite and dihydrate gypsum incorporating with analytical pure P2O5 can produce more C-S-H and ettringite with higher density in late stage.