INVESTIGATION OF THE PROPERTIES OF A WATERBORNE THERMAL INSULATION COMPOSITE BASED ON SHELL LIME-STONE-SHELL ROCK AND HOLLOW MICROSPHERES

Abstract

The aim of this study is to develop a technology for producing a water-dispersion thermal insulation composition based on limestone shell rock mining waste and an acrylate dispersion containing hollow microspheres, as well as to investigate the influence of filled binders on the physical, mechanical, and thermophysical properties of thermal insulation coatings incorporating limestone shell rock from the Zhetybay deposit, Karakiya District, Mangystau Region, Kazakhstan. The microstructure of shell limestone was investigated using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) with a JEOL JSM-7000F scanning electron microscope. The determination of the weight and atomic percentages of the major elements confirmed the carbonate nature of the studied raw material and its consistency with the mineral composition of shell limestone mining waste (wt.%/at.%: O – 50.25/59.34; Ca – 34.14/16.09; C – 15.61/24.56). It was established that, to obtain a water-dispersion composition with low density, it is advisable to use finely dispersed fillers in the form of powder, as well as hollow glass and aluminosilicate microspheres. The particle size of shell limestone powder was 5.67 × 10⁻⁶ m, while the contents of calcium carbonate (CaCO₃) and silica (SiO₂) were 71.0 wt.% and 22.5 wt.%, respectively. A relationship between the proportion and content of shell limestone and microspheres in the filled binder system was identified, demonstrating a significant variation in thermal conductivity within the range of 0.010–0.015 W/(m·°C), as well as changes in the density and adhesive strength of the thermal-insulating coating, reaching ρ₍dry₎ = 0.410–0.415 g/cm³ and σ₍adh₎ ≥ 2.05–2.08 MPa, respectively. The optimal composition of the water-dispersion thermal-insulating coating was determined. The content of the main components is as follows (wt.%): styrene–acrylic or acrylic dispersion, 20–25; shell limestone, 20–25; glass microspheres, 3–9; and aluminosilicate microspheres, 20–30