The microstructure of macrodefect-free cement with different polymer contents and the effect on water stability

The effect of different polymer contents on the microstructure of ordinary Portland cementbased macrodefect-free cement was studied by high voltage transmission electron microscopy. The microstructure, especially the morphology and composition of the gel matrix, of material with a low polymer content was significantly different from that of material with a high polymer content. The former consisted mainly of gelatinous material with some microcrystallites and with some porosity. The latter consisted of mainly pure non-porous polymer gel with little metallic content. Although the dry strength of the material with high polymer content was higher than that of the lower polymer content material, the former was extremely unstable after immersing in water. This was attributed to the difference in microstructure of the polymer gel as revealed by electron microscopy.