可溶性磷对大掺量磷石膏胶凝材料水化过程的影响

Effect of Soluble Phosphorus on Hydration Process of High Content Phosphogypsum Cementitious Materials

磷石膏中的杂质如残余酸、可溶性磷会对磷石膏胶凝材料的配比和强度发展造成很大影响。本文用两种不同品质的磷石膏,与矿渣和水泥复合制备磷石膏掺量为60%、70%和80%(质量分数)的胶凝材料,并对磷石膏进行湿磨改性。通过测试胶凝材料孔溶液pH值、矿渣水化程度和抗压强度,并结合XRD、SEM-EDS等测试方法探究可溶性磷杂质对大掺量磷石膏胶凝材料水化过程的影响。结果表明:大掺量磷石膏胶凝材料中硅酸盐水泥的最佳掺量与磷石膏中所含的可溶性磷杂质有关,杂质含量越高水泥最佳掺量越高;磷石膏通过湿磨中和预处理后,可改善胶凝材料的7 d强度,但并不能提高28 d强度;复合胶凝材料的强度取决于矿渣水化程度,水化过程中磷石膏中可溶性磷与水泥水化的Ca(OH)_(2)形成磷酸钙沉淀覆盖在矿渣表面上,阻碍了矿渣水化,是影响其强度发展的主要原因。

Impurities such as residual acid and soluble phosphorus content in phosphogypsum have a great impact on the ratio and strength development of phosphogypsum cementitious material.Two different qualities of phosphogypsum were used to composite with slag and cement to prepare cementitious materials with phosphogypsum content of 60%,70%,and 80%(mass fraction),and wet grinding modification was carried out on phosphogypsum.By testing the pH value of the pore solution of the cementitious material,the degree of slag hydration,and compressive strength,and combining XRD,SEM-EDS and other testing methods,the influence of soluble phosphorus impurities on the hydration process of high dosage phosphogypsum cementitious materials was explored.The results show that the optimal dosage of Portland cement in high dosage phosphogypsum cementitious material is related to the soluble phosphorus impurities contained in phosphogypsum.The higher the content of impurities,the higher the content of cement.After wet grinding pretreatment,7 d strength of the cementitious material can be improved,but cannot increase the 28 d strength.The strength of the composite cementitious material depends on the degree of slag hydration.During the hydration process,the soluble phosphorus in phosphogypsum and the Ca(OH)_(2) hydrated by cement form calcium phosphate precipitates on the surface of the slag,which hinders the hydration of the slag and is the main reason affecting the development of its strength.