Abstract Early hydration and microstructure of gypsum plaster (G) paste in different compositions and hydration time were studied by environment scanning electron microscope (ESEM) coupled with liquid nitrogen cooling. It was observed that small hemihydrate particles rapidly dissolved and hydrated, forming dihydrate crystals network around large hemihydrate particles, which makes an increasingly dense microstructure and promotes the setting of G paste. Besides, different chemical admixtures such as polycarboxylate (PC), hydroxy propyl methyl cellulose (HPMC) and starch ether (SE) would promote the flocculating or deflocculating between particles and therefore modify the fluidity of the paste. This work paves the way to the understanding the setting and rheology of hydraulic materials in the perspective of microstructure evolution.

中文翻译：

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环境扫描电镜揭示石膏灰泥早期水化及微观结构

摘要 采用环境扫描电子显微镜（ESEM）结合液氮冷却研究了不同成分和水化时间的石膏（G）膏体的早期水化和微观结构。观察到小的半水合物颗粒迅速溶解和水合，在大的半水合物颗粒周围形成二水合物晶体网络，这使得微观结构越来越致密并促进 G 糊剂的凝固。此外，聚羧酸酯（PC）、羟丙基甲基纤维素（HPMC）和淀粉醚（SE）等不同的化学外加剂会促进颗粒之间的絮凝或反絮凝，从而改变膏体的流动性。这项工作为从微观结构演化的角度理解水硬性材料的凝固和流变学铺平了道路。