碳化作用对镁质胶凝材料微观结构演变过程的影响
收稿日期: 2021-10-13
网络出版日期: 2022-06-22
基金资助
青海省应用基础研究项目(2021-ZJ-737);青海省重点研发与转化计划项目(2019-GX-165)
Effect of carbonization on evolution process of microstructure of magnesium oxychloride cement
Received date: 2021-10-13
Online published: 2022-06-22
为揭示碳化作用对镁质胶凝材料微观结构演变过程的影响,通过扫描电镜(SEM)、X射线衍射(XRD)和压力试验机,对室内养护5 a龄期的镁质胶凝材料净浆试样和30 a龄期的镁质胶凝材料房梁试样进行分析。结果表明,碳化作用对镁质胶凝材料的微观形貌和物相组成影响较大。空气中的二氧化碳由表及里渗入镁质胶凝材料中,在二氧化碳渗入的过程中引起镁质胶凝材料微观形貌和物相组成的变化。镁质胶凝材料的微观形貌主要由针棒状、多孔状向块状转变,物相由5·1·8[5Mg(OH)2·MgCl2·8H2O]相经2·1·1·6[2MgCO3·Mg(OH)2·MgCl2·6H2O]相最终转化为稳定的水菱镁矿和菱镁矿。由于碳化作用,镁质胶凝材料5 a龄期的抗压强度相比1 a龄期下降了22.1 MPa。因此,需要采用隔离方法处理镁质胶凝材料,以减少其碳化作用,延长其使用年限。
常成功 , 文静 , 董金美 , 郑卫新 , 阎峰云 , 肖学英 . 碳化作用对镁质胶凝材料微观结构演变过程的影响[J]. 无机盐工业, 2022 , 54(6) : 61 -65 . DOI: 10.19964/j.issn.1006-4990.2021-0546
To reveal the effect of carbonization on the evolution process of the microstructure of magnesium oxychloride cement,scanning electron microscope(SEM),X-ray diffraction(XRD) and pressure testing machines were used to analyze the pure slurry and roof beam of magnesium oxychloride cement which were cured for 5 years and 30 years in the indoor environment,respectively.The results showed that carbonization exhibited an obvious influence on the microscopic morphology and phase composition of magnesium oxychloride cement.The CO2 in the air penetrated into magnesium oxychloride cement from the surface to the inside,resulting in the change of the microscopic morphology and phase composition of magnesium oxychloride cement.The morphology of magnesium oxychloride cement was transformed mainly from needle,porous to block shape,meanwhile its phase composition also changed from 5·1·8[5Mg(OH)2·MgCl2·8H2O] to 2·1·1·6[2MgCO3·Mg(OH)2·MgCl2·6H2O] phase,and finally to the stable hydromagnesite and magnesite.Owing to carbonization,the compressive strength of magnesium oxychloride cement cured for 5 years decreased by 22.1 MPa compared with that maintained for 1 year.Therefore,it was necessary to use an isolation method to treat magnesium oxychloride cement to reduce carbonization and extend its service life.
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