改性磷石膏对超硫酸盐水泥水化特性的影响

Effect of Modified Phosphogypsum on Hydration Characteristics of Supersulfated Cement

本工作研究改性磷石膏对超硫酸盐水泥(SSC)早期水化热、强度、孔溶液pH值、水化产物和微观形貌的影响。与通用硅酸盐水泥(CPC)体系相比,SSC体系早期水化速率较慢、水化热较低、诱导期延长,第二放热峰出现延后,表现出较低的早期水化特性,磷石膏的改性方式可调控早期水化速率和体系水化活性。SSC体系主要水化产物为钙矾石和C-S-H凝胶,浆体pH值稳定在11,其强度与磷石膏特性有关,煅烧处理可提高其中后期强度,而石灰中和处理可提高全龄期强度。磷石膏经处理后,活性增加,产生更多的AFt和C-S-H凝胶,使其结构密实、强度增加。

The influence of modified phosphogypsumson early hydration heat,compressive strength,pH of the pore,hydration products and microstructure characteristics of supersulfated cement(SSC)were studied.SSC system had lower early hydration rate,lower hydration heat,longer induction period,and delayed second exothermic peak,which showed lower early hydration characteristics comparing with common Portland cement(CPC).Modification methods of phosphogypsum could regulate the early hydration rate and the hydration activity of the system.The main hydration products of SSC were AFt and C-S-H gels,the pH value was stable at 11,and its strength was depended on the characteristic of phosphogypsum.Calcination could improve the strength at the middle and late ages,while lime neutralization could improve the strength through the whole age.After treatment,the activity of phosphogypsum increased,resulting in more AFt and C-S-H gels,which made the structure dense and strength increasing.