Effective mineral additives for binders and concretes made from local kaolin clays

Abstract

The article discusses the possibilities of obtaining active mineral additives (AMD) from kaolin-containing clay raw materials of the Kyrgyz Republic. An analysis of the mineral and raw material base and a comparative assessment of the kaolin clays of Kyrgyzstan by chemical composition were carried out, which made it possible to note a high content of SiO2 from 48.5 to 71.5% and Al2O3 from 14.8 to 30.4 %. Microstructural and elemental analysis of the studied Kara Kech clay confirmed the presence of a finely dispersed lamellar matrix with a predominance of aluminosilicates, which indicates the predominance of Si elements, Al and O. The results of X-ray phase analysis (Fig.1) showed that the main clay phase is the mineral kaolinite in the range of 45-55% with an additional content of 15-20% illite. Preliminary studies indicate a high potential for pozzolanic activity after thermal activation.
Studies on the thermal activation of clay from the Kara-Keche deposit have been performed and optimal firing modes have been determined. It has been established that the kaolinite clays of Kara Keche acquire high pozzolan activity at a temperature of 650-700 °C. The use of activated clays in cement systems significantly increases the strength in the early stages of hardening by 73% after 7 days and by 40% after 28 days, which significantly increases the durability of cement composites, reducing the carbon footprint of building materials.