Synthesis and hydration study of Portland cement components prepared by the organic steric entrapment method

The four components of Portland cement; dicalcium silicate (Ca2SiO4), tricalcium silicate (Ca3SiO5), tricalcium aluminate (Ca3Al2O6), and tetracalcium aluminate iron oxide (Ca4Al2Fe3O10), were made by the PVA complexation process. Powders prepared by this new method can make relatively high yields of pure, synthetic, cement components of nano or sub-micron crystallite dimensions, high specific surface area, and extremely high reactivity at relatively low calcining temperatures, in comparison with conventional methods. The above advantages can enhance setting speed, increase strength, and lead to other desirable characteristics of Portland cement. Optimum synthesis conditions, such as PVA content, degree of polymerization of the PVA, and calcination temperature, were determined for each component. Hydration speed and strength of the synthesized, mixed cement paste were also studied at room temperature (25 degrees C). The powders and hydration behavior were characterized by microstructural examination (XRD, SEM) and specific surface areas were measured by nitrogen gas adsorption BET. DSC and Instron were used to study setting speed and compression strength. (c) 2003 RILEM. All rights reserved.