Abstract
A topical issue in the modernization of housing and communal services is increasing the energy efficiency of enclosing structures while maintaining the standard strength and durability of wall materials. The study aimed to investigate opportunities for the use of glass cullet and fly ash in the production of autoclaved silicate bricks to reduce their thermal conductivity. The tested characteristics included average density, the thermal conductivity coefficient, compressive and flexural strength, water absorption, and frost resistance. The introduction of glass powder and fly ash was found to consistently lower the average density of silicate bricks from 1,910–1,950 to 1,625–1,700 kg/m³ and the thermal conductivity from 0.88–0.91 to 0.52–0.54 W/(m•K). The optimal compositions (samples No. 2 and No. 3) reduced thermal conductivity by 25–30% compared to the control sample with compressive strength remaining above 17.5 MPa and frost resistance in the range of F27–F35. An analysis of microstructural and phase characteristics based on SEM and XRD data showed that the improvement of thermophysical properties was due to the formation of a finely porous structure and a mixed hydrate matrix containing tobermorite and an amorphous C–S–H phase. The results confirm the expedience of using glass cullet and fly ash to produce energy-efficient silicate bricks suitable for use in enclosing structures in the framework of modernizing the facilities of housing and community services, which will not require major changes to current production technologies.