STUDY OF THE COMBINED INFLUENCE OF INORGANIC PIGMENTS AND NANOCARBONATE ADDITIVES ON THE SYNTHESIS OF THE STRENGTH OF DECORATIVE CEMENTS

Abstract

The effect of inorganic pigments on the strength of cement systems modified with polycarboxylate plasticizers was studied and the possibility of compensating the negative effect of such pigments on the strength characteristics of cement systems by introducing a nanocarbonate additive was found. The research was carried out on cement systems based on white cement of different manufacturers, which differ in mineralogical composition Such cement systems are modified with polycarboxylate plasticizers in the form of dry powder and colored with blue, green and red inorganic pigments. When plasticizers are introduced, the water consumption of cement systems is reduced by 40% compared to cement systems without the introduction of plasticizers. The greatest effect is achieved with the introduction of plasticizers in the amount of 1.5% of the mass of cement. When coloring cement systems modified with polycarboxylate plasticizers with inorganic pigments in the amount of 3 to 9%, the water consumption of such systems increases and their strength decreases. As the number of pigments increases, the strength of the samples decreases. At the same time, blue and green colors have less effect on the strength of the cement system, and the greatest decrease in strength is observed on samples colored with red pigment. When red pigment is dosed in the amount of 9% of the mass of cement, the strength of the cement system decreases by 5-16% at the age of 3 days, by 9-14% at the age of 7 days and by 18-21% at the age of 28 days. In the system plasticized with the hyperplasticizer Melflux 5581 F, when red pigment is dosed in the amount of 3 and 6%, there is a decline in early strength at the age of 3 days compared to other systems. When a nanocarbonate additive in the form of a suspension is introduced into the composition of the pigmented cement system, the intensity of the process of recrystallization of ettringite into the monosulfate form decreases and the formation of carbonate ettringite, which later serves as a substrate for the directed crystallization of fibrous calcium hydrosilicates, which ensures the strength of cement systems over time.