PHYSICO-CHEMICAL CHARACTERISTICS OF THE HYDRATION PROCESSES OF MODIFIED COLORED PORTLAND CEMENT

Abstract. The article presents the results of research on the physico-chemical features of the hydration processes of modified Portland cement and determines the influence of nanocarbonate additives on the processes of artificial stone structure formation. Research was conducted on cement systems based on plasticized white Portland cement with the addition of red pigment and modified with a nanocarbonate additive in the form of a dispersion. It was established that the structure of cement stone without the addition of pigment is more homogeneous, and when pigment is added, microcracks are formed due to internal stresses arising in the contact zone. The formation of cracks can be explained by the features of the pore structure formed when the pigment is added. Since the addition of pigment for a dough of normal thickness requires an increase in the water-cement ratio, more pores are formed in such a cement stone that cannot be immediately filled with cement hydration products. When a nanocarbonate additive is introduced into the pigmented cement system, we can observe the overgrowth of cracks formed as a result of the addition of pigment, the formation of a fairly homogeneous structure, and the overgrowth of pores. Regulation of the strength and operational characteristics of colored cements is relevant, since the introduction of pigment leads to a decrease in the strength of artificial stone. Solving this problem by means of nanomodification reveals a new possibility of stabilizing the strength and operational characteristics of not only white but also colored cements. The introduction of a nanocarbonate additive in the form of a dispersion to the pigmented cement system contributes to the formation of a more perfect dense and uniform structure of cement stone. As a result, it is possible to obtain a cement system resistant to the appearance of microcracks, with less porosity, including open porosity, which is important for colored cements in the composition of plaster mixtures