不同减水剂对高强石膏浆体工作性的影响与作用机理  

Effects and Mechanism of Different Water Reducers on Workability of High-Strength Gypsum Paste

作　　者：陆亚运 罗旭 刘川北[3] LU Yayun;LUO Xu;LIU Chuanbei(School of Civil Engineering,Southeast University,Nanjing 211189,China;School of Materials Science and Engineering,Southeast University,Nanjing 211189,China;School of Materials and Chemistry,Southwest University of Science and Technology,Mianyang 621010,China)

机构地区：[1]东南大学土木工程学院,南京211189 [2]东南大学材料科学与工程学院,南京211189 [3]西南科技大学材料与化学学院,绵阳621010

出　　处：《硅酸盐通报》2023年第1期205-212,共8页Bulletin of the Chinese Ceramic Society

基　　金：高性能土木工程材料国家重点实验室开放课题(2022CEM007);西南科技大学博士基金(20zx7107)。

摘　　要：采用旋转流变仪、微量热仪、环境扫描电子显微镜(ESEM)和X射线衍射仪(XRD)等分析测试方法,系统研究了萘甲醛磺酸盐(NFS)、磺化三聚氰胺甲醛(SMF)和聚羧酸(PC)三种减水剂对高强石膏浆体流变和凝结性能的影响规律和作用机理。结果表明,三种减水剂对高强石膏浆体流动度提升的大小顺序为PC>SMF>NFS。减水剂的分散作用促进了半水石膏的溶解,但延缓了二水石膏的析晶成核,同时会使浆体产生分层离析和剪切增稠现象。在饱和掺量下,NFS延缓了二水石膏的析晶成核,但促进了二水石膏晶体生长发育和网络结构的形成,因此对浆体早期水化和凝结时间影响不大;SMF不影响二水石膏的析晶成核,但可以促进二水石膏晶体生长发育和网络结构的形成,从而加速浆体早期水化进程并使凝结时间显著缩短;PC会同时阻碍二水石膏晶体的成核和生长发育,因而会大幅延缓浆体早期水化进程,使凝结时间线性增加。By means of rotational rheometer,microcalorimeter,environmental scanning electron microscope(ESEM)and X-ray diffractometer(XRD),the effects and mechanism of three kinds of water reducer including naphthalene formaldehyde sulfonates(NFS),sulfonated melamine formaldehyde(SMF)and polycarboxylate(PC)on the rheological and setting properties of high-strength gypsum paste(HSGP)were studied systematically.The results show that the order of improving the fluidity of HSGP by the three water reducers is PC>SMF>NFS.The deflocculation effect of water reducer promotes the dissolution of hemihydrate gypsum,delays the nucleation of dihydrate gypsum,and causes the HSGP to produce segregation and shear-thickening.Under the saturated content,NFS delays the nucleation of dihydrate gypsum,but promotes the growth and formation of crystal-network-structure(CNS)of dihydrate gypsum,so it has little effect on the early hydration and setting time of HSGP.SMF promotes both the growth and formation of CNS of dihydrate gypsum crystals,without affecting the nucleation of dihydrate gypsum,thus accelerating the early hydration process of HSGP and shortening the setting time significantly.PC hinders both the nucleation and growth of dihydrate gypsum crystals,thus greatly postponing the early hydration process of HSGP and linearly improving the setting time.

关 键 词：高强石膏 减水剂 流变 剪切增稠 早期水化 微观结构 

分 类 号：TU526[建筑科学—建筑技术科学]