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The article discusses the problem of increasing the water resistance and strength of a composite gypsum binder for concrete. The effect of complex modification of a composite gypsum binder with a micro-reinforcing, polymineral micropuzzolanic additive filler and superplasticizer from Sika was investigated. The use of filler additives in optimal ratios made it possible to obtain a composite gypsum binder with a softening coefficient of 0.9.

The maps of local heat fluxes in the composite matrix with randomly located heat-insulating and heat-conducting inclusions have been calculated in this work. It was shown that with a significant difference in the thermal conductivity of inclusions and matrix, the main heat transfer occurs through the induced heat-conducting channels. It was found that the weighted average angles of local heat fluxes deviation from the direction of the temperature difference between the sample faces depend on the concentration of heat-insulating and heat-conducting inclusions of various sizes. A sublinear decrease or super linear increase in the effective thermal conductivity of the composite with an increase in the concentration of heat-insulating or heat-conducting inclusions, respectively, was associated with a change in the path length of local heat fluxes due to the flow at an angle to the direction of the temperature difference. An approximation formula for the dependence of the composite effective thermal conductivity on the filler concentration has been proposed, which makes it possible to take into account the presence of both heat-conducting and heat-insulating inclusions.