聚合物和纤维对石膏基材料早期水化与浆体微结构的影响  

Influence of Polymers and Fibers on Early Hydration and Microstructure of Gypsum-based Materials

作　　者：刘川北[1] 高建明[2] 孟礼元 刘来宝[1] 张礼华[1] 张红平[1] 罗旭 LIU Chuanbei;GAO Jianming;MENG Liyuan;LIU Laibao;ZHANG Lihua;ZHANG Hongping;LUO Xu(School of Materials Science and Engineering,Southwest University of Science and Technology,Mianyang 621010,Sichuan,China;School of Materials Science and Engineering,Southeast University,Nanjing 211189,China;Nanchong Sixin Building Materials Co.,Ltd.,Nanchong 637973,Sichuan,China)

机构地区：[1]西南科技大学材料科学与工程学院,四川绵阳621010 [2]东南大学材料科学与工程学院,南京211189 [3]南充四新建材有限公司,四川南充637973

出　　处：《材料导报》2022年第8期211-215,共5页Materials Reports

基　　金：国家自然科学基金(51978590,51808464);西南科技大学博士基金(20zx7107)。

摘　　要：研究石膏基材料的早期水化与浆体微结构对于理解不同外加剂对石膏基材料的作用机理以及改善石膏基材料浆体的工作性能都具有十分重要的意义。本工作采用水化热测试、动态流变测试以及液氮冷冻与环境扫描电镜测试相结合等方法,系统研究了聚乙烯醇(PVA)、丁苯橡胶(SBR)、聚乙烯醇纤维(PVAF)和聚丙烯纤维(PPF)对石膏基材料早期水化过程和浆体微观结构变化的影响。结果表明:石膏基材料的早期水化主要包括半水石膏颗粒溶解、二水石膏晶体成核、生长发育以及晶体网络结构形成四个过程;PVA一方面吸附在半水石膏颗粒表面,阻碍颗粒间有效接触和溶解,另一方面分散到浆体间隙溶液中,吸收大量自由水分并使有效水膏比降低,从而加快晶体成核;SBR吸附到石膏颗粒表面会使絮凝结构解体,同时阻碍颗粒溶解、晶体成核、生长发育以及晶体网络结构形成;两种纤维分散到石膏颗粒间可以促进絮凝网络结构形成,同时亲水性PVAF表面还吸附了大量自由水分和Ca^(2+),使晶体优先在其表面成核,从而改善纤维与浆体的界面和粘接性能。It is of great significance to study the early hydration and microstructure of gypsum-based materials(GM)for understanding the working mechanism of different admixtures and improving the workability of pastes.Therefore,in this work the early hydration and microstructure of GM pastes containing polyvinyl alcohol(PVA),butadiene styrene rubber(SBR),polyvinyl alcohol fiber(PVAF)and polypropylene fiber(PPF)were investigated by the hydration heat test method,oscillatory rechnology test method and environment scanning electron microscope(ESEM)coupling with liquid nitrogen cooling method.The results show that the early hydration of GM pastes can be divided into four stages,which are the dissolution of hemihydrate particles,the nucleation,growth of dihydrate crystals and the formation of crystal-network-structures(CNS).It has been pro-ven that both polymers can be adsorbed on hemihydrate particles,hindering the effective contact and dissolution of particles.Simultaneously,SBR can be also preferentially adsorbed on dihydrate crystals,impeding the growth of crystals and formation of CNS.Besides,both fibers dispersing among gypsum particles can strengthen flocculation structures,and simultaneously PVAF can absorb a lot of free water and calcium ions,which makes the preferential nucleation of crystals on its surface,therefore improving the interface and binding properties between PVAF and pastes.

关 键 词：石膏基材料 振荡流变 水化热 微观结构 

分 类 号：TU526[建筑科学—建筑技术科学]