基于DEF的砂浆变形分析

Analysis of mortar deformation based on DEF

混凝土预制构件常因高温养护而产生延迟钙矾石形成(DEF)的问题,导致混凝土体积膨胀而发生破坏。将纯水泥砂浆试件、掺矿粉砂浆试件以及对应的净浆试件,分别进行常压蒸汽养护和组合养护,并将养护后的样品浸没在常温的淡水和海水环境中。使用高精度的激光测距仪监测砂浆试件的变形,采用X射线衍射分析仪进行成分分析。试验结果表明:热养护后的试件,X射线衍射图谱都未发现明显的AFt衍射峰,28 d常温水环境中可发现DEF情况。在常温的淡水环境与海水环境中,不同养护制度的砂浆试件变形差异较大,海水环境下养护的试件膨胀变形趋势更明显,掺加矿粉后的试件相对于纯水泥试件出现更明显的膨胀变形趋势。

The problem of delayed ettringite formation(DEF)is often caused by the high-temperature curing of precast concrete components,which leads to the concrete volume expansion and concrete damage.Pure cement mortar specimen,mineral powder and mortar mixed specimen and corresponding pure mortar specimen were respectively cured by atmospheric steam curing and combined curing,and the cured specimens were soaked in fresh water and sea water environment at normal temperature.A high-precision laser rangefinder was used to monitor the deformation of mortar specimens,and the X-ray diffraction analyzer was used to analyze their compositions.The experimental results indicate that there is no obvious AFt diffraction peak in the X-ray diffraction pattern of the specimens after heat curing,and DEF can be found in the water environment at normal temperature of 28d.Significantly different deformation of mortar specimens with different curing systems,more obvious expansion deformation trend of specimens cured in sea water,and more obvious expansion deformation trend of the specimens mixed with mineral powder than that of pure cement specimens can be seen in fresh water and sea water environment at normal temperature.