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.