减水剂对磷石膏基建筑石膏性能的影响

Effect of Water Reducing Agent on Properties of Phosphogypsum Based Building Gypsum

以云南安宁某磷肥厂的磷石膏为原料,制备了磷石膏基建筑石膏。采用四种不同类型的减水剂,即木质素磺酸钙(MG)、萘系减水剂(FDN)、三聚氰胺减水剂(SMF)、聚羧酸减水剂(PS)四种物质,考察了不同减水剂的掺量对磷石膏基建筑石膏的标准稠度用水量、减水率、凝结时间与抗折、抗压强度的影响。结果表明,MG不适合作石膏减水剂,改性效果较好的是SMF减水剂,掺入量为0.3wt%。通过对掺杂减水剂后石膏试件的SEM表征,初步对石膏减水改性过程进行了机理分析。发现减水剂主要是通过物理方法进行改性,当其加入建筑石膏水化体系中时,会使石膏内部结构变得更为致密,从而降低标准稠度用水量,最终增加石膏试件的强度。

Phosphogypsum based building gypsum was prepared by phosphogypsum from a phosphate fertilizer plant in Anning,Yunnan province.Four different types of water reducing agents,namely calcium lignosulfonate(MG),naphthalene series water reducing agent(FDN),melamine water reducing agent(SMF)and polycarboxylic acid water reducing agent(PS)were used to investigate the effects of different dosage of water reducing agent on water consumption for standard consistency,water reduction rate,setting time and flexural and compressive strength of phosphogypsum based building gypsum.The results show that MG is not suitable for gypsum water reducing agent,and the better modified agent is SMF water reducing agent,the content of which is 0.3wt%.By means of SEM characterization of gypsum specimens doped with water reducing agent,the mechanism of water reducing modification of gypsum is preliminarily analyzed.It is found that the water reducing agent is mainly modified by physical methods.When it is added to the building gypsum hydration system,it makes the internal structure of gypsum denser,thereby reducing the water consumption of standard consistency and eventually increasing the strength of the gypsum test piece.