The expediency of using a finely ground mineral additive from burnt mudstone clay for the production of heat-resistant expanded clay concrete based on Portland cement with a rational dose of the additive of 30...50% by weight of the binder is shown. Compositions of heat-resistant expanded clay concrete with a maximum permissible application temperature of I10 classes in compressive strength up to B15 and an average density of up to 1500 kg/m3 have been developed. The efficiency of the technology for obtaining heat-resistant expanded clay concrete using pre-forced electric heating of the concrete mixture up to 60°C is substantiated and rational technological parameters of electric heating are determined. The residual strength of heat-resistant expanded clay concrete obtained using the developed technology, after short-term heating to 1000oC, exceeds 0.65 of the initial, which is higher than the values for analogues according to SP 27.13330.2017. The coefficient of linear temperature expansion of the developed heat-resistant expanded clay concrete in the temperature range of 200...1000oC varies within 2 ...5,8ˑ10-6 1/oC. The increase in the coefficient of thermal conductivity of the studied concretes with an increase in temperature up to 1000°C is up to 34%. The heat resistance of heat-resistant expanded clay concrete at 800oC, obtained using the technology of pre-forced electric heating of the mixture, was 12, 14 and 15 air heat changes, respectively, at a temperature of pre-forced electric heating of 60, 80 and 90 оC.
Keywords: heat-resistant expanded clay concrete, fine-ground mineral additive, mudstone, thermal conductivity coefficient, coefficient of linear thermal expansion, residual strength