无机盐工业
主管:中海油天津化工研究设计院有限公司
主办:中海油天津化工研究设计院有限公司
   中海油炼油化工科学研究院(北京)有限公司
   中国化工学会无机酸碱盐专业委员会
ISSN 1006-4990 CN 12-1069/TQ

无机盐工业 ›› 2022, Vol. 54 ›› Issue (8): 119-124.doi: 10.19964/j.issn.1006-4990.2021-0648

• 环境·健康·安全 • 上一篇    下一篇

不同硫酸盐环境下铝酸三钙的劣化过程及机制

王炳监1(),齐道正1,陈登2   

  1. 1.盐城工业职业技术学院建筑工程学院,江苏 盐城 224005
    2.苏州科技大学土木工程学院
  • 收稿日期:2021-10-25 出版日期:2022-08-10 发布日期:2022-08-11
  • 作者简介:王炳监(1988— ),男,硕士,讲师,研究方向为结构工程及土木工程材料;E-mail:wangbingjian1988@163.com
  • 基金资助:
    江苏省高等学校自然科学研究项目(20KJB560007);安徽省先进建筑材料工程实验室开放课题(JZCL006KF)

Degradation processes and mechanism of tricalcium aluminate in different sulfate environment

WANG Bingjian1(),QI Daozheng1,CHEN Deng2   

  1. 1.Institute of Civil Engineering,Yancheng Polytechnic College,Yancheng 224005,China
    2.College of Civil Engineering,Suzhou University of Science and Technology
  • Received:2021-10-25 Published:2022-08-10 Online:2022-08-11

摘要:

主要研究了硫酸钠和硫酸镁溶液对铝酸三钙(C3A)单矿浆体损伤的影响,使用外观、膨胀率、质量变化研究了浆体宏观性能的劣化,并进一步采用半定量X射线衍射分析(XRD)和扫描电子显微镜(SEM)分析了浆体的侵蚀产物含量和微结构,最后采用光学显微镜原位研究了C3A-CaSO4体系下钙矾石的形成特征。研究结果表明:外部的硫酸根能够扩散进入水泥基材料与含铝相的水化产物发生反应形成钙矾石,针棒状钙矾石在有限的空间中不断形成,会导致试件膨胀并引起质量的增加。在硫酸钠溶液中浸泡120 h后浆体中钙矾石质量分数上升到20.12%,而硫酸镁溶液中浆体的钙矾石质量分数仅为6.87%。与硫酸钠溶液不同,镁离子的存在会与孔溶液中的氢氧根发生反应形成氢氧化镁附着在表层,抑制了外部硫酸根的侵入,同时该环境下氢氧根的消耗引起的较低pH有利于石膏的生长。

关键词: 硫酸盐侵蚀, 铝酸三钙, 硫酸钠, 硫酸镁

Abstract:

The effect of sodium sulfate and magnesium sulfate solution on the damage of tricalcium aluminate single ore slurry was studied.The deterioration of macro properties of the slurry was studied by appearance,expansion rate and mass change.The content of corrosion products and microstructure of the slurry were further analyzed by semi quantitative X-ray diffraction(XRD) and scanning electron microscopy(SEM).Finally,the formation characteristics of ettringite in C3A-CaSO4 system were studied in situ by optical microscope.The results showed that the infiltration of external sulfate ions would react with the original hexagonal plate calcium sulphoaluminate hydrate to form ettringite.The continuous formation of needle rod ettringite in a limited space would lead to specimen expansion and increase in mass.In the sodium sulfate solution,the ettringite content in the slurry increased to 20.12% after 120 h soaking,while the ettringite content in the magnesium sulfate solution was only 6.87%.Due to the existence of magnesium ions in magnesium sulfate solution,magnesium hydroxide precipitates would be formed and attached to the surface of single mineral cement stone,which inhibited the invasion of external sulfate ions.At the same time,the lower pH caused by the consumption of hydroxyl ions in this environment was conducive to the growth of gypsum.

Key words: sulfate attack, tricalcium aluminate, sodium sulfate, magnesium sulfate

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