Production of white cement by low-temperature firing

The object of research was silicate systems based on CaO–SiO2–AL2O3 oxides for the production of white cement under the condition of reducing the maximum firing temperature and energy intensity of the products. A complex of raw materials of different genesis was chosen for the study – chalk, pyloquartz, aluminum hydroxide. The criteria for the selection of raw materials were increased reactivity during firing and minimization of the content of colored oxides. During the research, methods of physico-chemical analysis of silicates and standardized testing of properties were comprehensively applied. Determination of the rational compositions of the raw material mixture was carried out using the created computer program «RomanCem». Based on the analysis of the calculation results, a significant value of the quantitative ratio of aluminum-silica-containing components Ca/Cp was determined. It was established that in the interval of the quantitative ratio Ca/Cp from 0.4 to 0.6, the silica modulus of the binder changes in an inversely proportional dependence within n=3.8–2.5 at a low content of colored iron oxides at the level of C=0.14–0.17 %. The compositions of the raw material mixture based on chalk with the use of an aluminum-silica-containing complex of aluminum hydroxide-powder quartz were determined, which allow, at the maximum firing temperature of 1100–1200 °C, to obtain a mineral binder that exceeds natural or Roman cement in terms of strength (21–27 MPa versus 10–15 MPa) and whiteness (80–85 % versus 55–60 %). Peculiarities of phase transformations in the material during low-temperature firing as a factor of structure and properties are noted. The development and practical use of white cement, obtained by reducing the maximum firing temperature and, accordingly, specific fuel consumption, reveals additional reserves for the production of mineral binders, contributes to the comprehensive solution of issues of resource conservation and production technology of silicate building materials.