Characterization of a gypsum plaster sample by SEM

Gypsum plaster sample prepared from 30 wt% hemihydrate binder, 70 wt% AAC aggregate (batch 1), 0.01 wt% high-performance set retarder Retardan-2025 P, 0.06 wt% anionic surfactant based air entraining admixture Sika DSM-A3 and 0.03 wt% cellulose-ether Tylose MH 60001 P4. The water/plaster ratio was 0.75 which yielded a consistency according to the flow table method of 158.5 mm. The dry density is 0.74 g/cm³. Scanning electron microscopy (SEM) was performed on a Thermo Scientic Quattro S ESEM and secondary electron images of uncoated fracture surfaces were obtained in high vacuum mode at an acceleration voltage of 2-5 kV.本研究所制备的石膏抹灰试样以30 wt%半水石膏胶凝材料、70 wt%加气混凝土（AAC）集料（批次1）为基料，同时掺入0.01 wt%高性能缓凝剂Retardan-2025 P、0.06 wt%阴离子表面活性剂基引气外加剂Sika DSM-A3以及0.03 wt%纤维素醚Tylose MH 60001 P4。该试样的水膏比为0.75，依照跳桌法测得其流动度扩展值为158.5 mm，干燥密度为0.74 g/cm³。采用赛默飞世尔科技（Thermo Scientific）Quattro S环境扫描电子显微镜（ESEM）开展扫描电子显微镜（SEM）表征，在高真空模式下以2~5 kV的加速电压，采集未镀膜断裂面的二次电子图像。