改性磷石膏球作缓凝剂对水泥性能的影响

Effect of modified phosphogypsum spheres as retarder on cement properties

研究了工业化生产的改性磷石膏球对水泥标准稠度用水量、凝结时间、胶砂流动度、胶砂强度及水泥与减水剂相容性的影响,并与原状磷石膏和天然石膏进行对比,结合X-射线衍射、综合热分析等微观测试,分析了改性磷石膏球对水泥水化产物相、水化程度的影响.结果表明:采用改性磷石膏球配制的水泥,其初凝、终凝时间与掺配原状磷石膏水泥相比分别缩短217 min、227 min,1d、3d强度显著高于原状磷石膏配制的水泥,28d强度高于天然石膏配制的水泥,且标准稠度用水量、胶砂流动度、与减水剂的相容性等指标优于天然石膏配制的水泥.改性磷石膏球对水泥早期水化无不良延缓作用,且能提高水泥后期水化程度.综合对比上述三种石膏对水泥性能影响的各项指标,认为改性磷石膏球可以完全替代天然石膏作水泥缓凝剂.

Compared with the original phosphogypsum and natural gypsum,the efects of moified phosphogypsum spheres from industrial production on the water requirement of normal consistency,setting time,mortar fluidity and strength as well as the compatibility of cement and water-reducing agent were studied.By means of micro-tests such as X-ray diffraction and comprehensive thermal analysis,the efects of modifed phosphogypsum spheres on the phase and degree of hydration of cement were analyzed.The results revealed that compared with the cement compounded with original phosphogypsum,the initial and final setting time of the cement compounded with modified phosphogypsum spheres is shortened by 217 min,227 min,respectively,the strength of cement compounded with modified phosphogypsum spheres at 1 d and 3 d was significantly higher than that of original phosphogypsum,and the strength of 28 d is higher than that of natural gypsum,in addition,the indicators of water requirement of normal consistency,fluidity of mortar and compatibility with water-reducing agent are better than the cement compounded with natural gypsum.Modified phosphogypsum spheres have no adverse retarding effect on early hydration of cement,and can improve the late hydration of cement.Based on a comprehensive comparison of various indicators of the effects of the above three types of gypsum on cement performances,it is believed that modified phosphogypsum spheres can completely replace natural gypsum as a cement retarder.