Improving the production technology of multilayer building products with enhanced thermophysical and strength characteristics

Abstract

Thermal protection requirements of SP 50.13330.2024 combined with the climate data of SP 131.13330.2025 set a basic required heat transfer resistance of 2,93 м²·°C/W for external walls in the central part of European Russia, a value that a conventionally configured three-layer reinforced concrete product with a steel tie system fails to reach: its reduced resistance amounts to 2,823 м²·°C/W against a nominal value of 3,522. An author's calculation model of a multilayer wall product has been developed, linking the parameters of the manufacturing stage and the layer configuration with the reduced heat transfer resistance, the thermal homogeneity coefficient and the forces acting in the flexible ties. A coupled thermal and structural calculation was performed for five configurations under GOST 31310-2015 and SP 63.13330.2018. Replacing steel ties with glass fibre reinforced polymer ties at unchanged geometry raises the reduced resistance to 4,549 м²·°C/W and the thermal homogeneity coefficient from 0.724 to 0.840, reducing the tie force caused by seasonal thermal deformation of the outer layer by a factor of 3,6. The elasticity of the reduced resistance with respect to tie spacing drops from 0,305 to 0,007. Removing metal from the insulation zone shifts tie spacing into the group of purely structural parameters, and the leading source of the remaining losses becomes the product joint together with the accuracy of the middle layer thickness achieved during moulding.