Optimization of the composition and properties of lightweight materials based on liquid glass

Introduction. The use of aluminosilicate microspheres makes it possible to produce lightweight, high-strength fired materials. The use of liquid glass as a binder allows products at a firing temperature of 400 °C, significantly reducing energy consumption compared to ceramic materials. The aim of the research presented in the article was to develop and test a method for assessing the properties of fired products based on liquid glass and silicate microspheres, as well as to select optimal formulation and process parameters. Methods and materials. Liquid glass with a density of 1400 kg/m³ is used as a binder, and aluminosilicate microspheres are used as a lightweight filler. The properties of the products were studied according to standard methods. The experiment was conducted using statistical and numerical methods. Results. A method for predicting the properties of fired products has been devel-oped, and formulation and process problems have been solved based on its application. It has been established that for a product with the highest compressive strength, the most suitable composition would be one containing 34% liquid glass, and the molding pressure should be 4.6 MPa. In this case, the compressive strength will be 16.2 ± 0.6 MPa; the average density is 711 ± 38 kg/m3 and the thermal conductivity is 0.0114 ± 0.0006 W/(moC). The decrease in compressive strength after 75 freeze-thaw cycles (compared to the strength of dry samples) is 8–11%, and after 100 cycles – 11–14%. Discussion. The formation of the properties and structure of the material is based on the processes of uniform distribution of the binder over the surface of the gra-nules with the pressing of the system and crystallization of the binder during the firing process with the formation of strong contact between the granules. Conclusion. Firing materials based on microspheres have a more developed sur-face of a single pore space, which affects their water absorption, and, consequent-ly, strength, thermal conductivity and operational durability.