速凝剂对低水胶比浆体早期水化与微观结构的影响  

Effects of Accelerators on the Early Hydration and Microstructure of Paste with Low Water-Binder Ratio

作　　者：罗彪[1] 罗正东[1] 任辉启 郭瑞奇 LUO Biao;LUO Zhengdong;REN Huiqi;GUO Ruiqi(College of Civil Engineering,Xiangtan University,Xiangtan 411105,Hunan,China;National Defense Engineering Institute,Academy of Military Science of PLA,Luoyang 471023,Henan,China)

机构地区：[1]湘潭大学土木工程学院,湖南湘潭411105 [2]军事科学院国防工程研究院,河南洛阳471023

出　　处：《材料导报》2023年第9期87-93,共7页Materials Reports

基　　金：国家自然科学基金(12072309);湖南省科技厅湖南创新型省份建设专项(2019RS1059);中国水利水电科学研究院水利部水工程建设与安全重点实验室开放研究基金(202109);湖南省教育厅科学研究项目(21B0123);湖南省研究生科研创新项目(QL20210155)。

摘　　要：低水胶比、高胶凝材料掺量的超高性能混凝土(UHPC)在常温养护条件下易产生凝结硬化不及时的问题。为促进UHPC在隧道初支、工程结构快速修复中的推广应用,拟采用有碱速凝剂(NA)和无碱速凝剂(AS)提升低水胶比浆体的早期凝结硬化速率。本工作通过水化热、水化溶出离子浓度、凝结时间和抗压强度试验研究速凝剂作用下低水胶比浆体的早期水化行为及凝结硬化规律,采用X射线衍射、SEM形貌观察和EDS能谱等手段对水化产物物相组成及微观结构演变规律进行了分析。结果表明,速凝剂的掺入加快了低水胶比复合胶凝材料浆体的早期水化速率,同时也促进了浆体的凝结硬化;NA对UHPC的促凝效果优于AS,其中NA-2%的1 d抗压强度为53.3 MPa,28 d强度比为94.9%,而AS-4%的1 d抗压强度为38.9 MPa,28 d强度比为92.3%;速凝剂促使低水胶比浆体快速生成大量水化产物,进而提高了浆体早期微观结构的致密性,且水化产物物相组成受速凝剂类型的影响较为显著。Ultra-high performance concrete(UHPC)with low water-binder ratio and high cementitious material content usually occurs a problem of slowly setting and hardening under room temperature curing conditions.In order to promote the popularization and application of UHPC in the initial support of tunnels and rapid repair,it is proposed to use alkaline and alkali-free accelerators(referred to as NA and AS,respectively)to increase the early setting and hardening rate of the paste with low water-binder ratio.In this work,the early hydration behavior and setting and hardening of paste with low water-binder ratio in the presence of accelerators were studied through the tests of the isothermal calorimetry,released ion concentration,setting time and compressive strength.And the phase composition and microstructure evolution of hydration products were analyzed by X-ray diffraction,SEM morphology observation and EDS spectroscopy.The results show that the addition of accelerators accelerates the early hydration rate of the composite-cementitious-materials pastes with low water-binder ratio,and at the same time contributes to the setting and har-dening of the pastes.The acceleration effect of NA on UHPC is better than that of AS.The 1 d compressive strength of NA-2%was 53.3 MPa,and the 28 d strength ratio was 94.9%,while the 1 d compressive strength of AS-4%was 38.9 MPa,and the 28 d strength ratio was 92.3%.Accelerators promote the rapid formation of a large number of hydration products in the pastes with low water-binder ratio,thereby improving the compactness of the early microstructure,and the phase composition of hydration products is significantly affected by the type of accelerators.

关 键 词：低水胶比 速凝剂 早期水化 水化产物 微观结构 

分 类 号：TU528.53[建筑科学—建筑技术科学]