蒸养水泥基材料的肿胀变形规律与控制

为掌握蒸养过程中水泥基材料的变形规律及其关键影响因素,基于铁路混凝土预制构件典型蒸养制度,试验研究不同胶凝材料组成试件在蒸养过程中的线度变形随蒸养时间的变化规律,研究不同水灰比、掺矿物掺合料等因素对蒸养试件肿胀变形的影响以及蒸养和标养条件下试件的水化物相,分析蒸养前自由水含量与蒸养试件肿胀变形的相互关系。研究结果表明:试件在蒸养过程中的不同阶段表现出显著不同的变形规律,试件的肿胀变形主要发生在升温阶段的初始结构形成期;蒸养水泥基材料的肿胀变形主要受蒸养前体系的固相组成及自由水含量(初始含水量)的影响。为较好地控制蒸养水泥基材料的肿胀变形,初始水灰(胶)比宜不大于30%,并采用矿物掺合料取代部分水泥。

Expansive deformation behavior of steam-cured cementitious materials and corresponding control measurement

For the sake of understanding expansive deformation behavior of cement-based materials under steam curing condition,a serial of experiments were carried out to investigate the linear expansive deformation of specimens with different water-binder ratios and binder compositions based on the typical steam-curing regime of railway precast concrete element production.X-ray diffraction analysis was used to determine the hydration products of samples.The relationship between expansive deformation value and free water content of sample before steam curing was also analyzed.The results indicate that specimens show different deformation characteristics in different stages of the whole steam curing process.The expansive deformations of specimens significantly increase in heating duration and subsequently decrease until to stable status.Expansive deformation of specimen is mainly influenced by the solid phase type and free water content before steam curing(or initial water content).Through choosing a water-binder ratio no more than 0.30 and partially replacing cement by mineral admixture,expansive deformation of cement-based materials during steam curing can be effectively reduced.