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The subject of the study is to optimize the compositions containing frost-resisting complex organic and inorganic additives (FRA) that provide the required level towards freezing temperature when constructing cement-mineral layers (CML) of road dressing (pavement). As a prerequisite to carry out these studies is the necessity to preserve the liquid phase in CML during asphalt laying at low (subzero) air temperatures, as well as ensuring a given level stated to the performance criteria and durability of road dressing layers. In our studies, we applied the comprehensive approach to the experiment, concluding in a choice of FRA components and in the use of experiment planning. The influence of functional additives and their quantitative composition on the freezing temperature (Tz ) during the experiment optimization in line with the D-optimal second-order plan has been considered. A mathematical model of the process has been obtained. We have found that the most significant mixture is the content of sodium formate (SF), compared to calcium chloride (CaCl2) and a superplasticizer based on the polycondensation product of naphthaleisulfonic acid and formaldehyde (C-3), the amount of which varies in the series 3>1>0.3. The obtained results on optimization allow to choose FRA compositions that provide the ability to perform construction works in conditions of subzero temperatures up to −15.6 °C.

The paper considers the influence of an antifrosty additive of sodium formate (SF) on the kinetics of hardening of cement-bound mixes (CBM) in the bases of road pavements at air temperatures from 00C to (-15) 0C with a cement content of 7.0% and 10.0%. The authors establish that the highest intensity of CBM hardening was noted in the first 7 days of hardening, at which the strength was 50-60% of the strength of the material at the age of 28 days. The SF modifier provides an increase in compressive strength (Rcs) of the material depending on the amount of additive and air temperature. The study makes it possible to establish the optimal consumption of SF for different temperature regimes of hardening of mixtures and at the indicated cement contents. The use of SF provides a 30% set of strength at a temperature not lower than (-5) °C. Modification of CBM with additives of SF provides the opportunity to increase the volume of construction of pavement foundations by performing work during periods of the year with lower air temperatures.

The complex introduction of organosilicon compound (octyltriethoxysilane) and electrolyte (sodium hydroxide) maximizes the frost resistance and strength of soil cement. However, the effect of complex additive based on octyltriethoxysilane and sodium hydroxide on the soil cement structure has not been sufficiently studied. Therefore, the aim of this work was to study the phase composition of hydrated newgrowths and soil minerals in soil cement with optimal content of complex additives. The study was conducted by methods of complex thermal analysis, X-ray powder diffraction and electron microscopy. On the XRD pattern of the sample with and without complex additive, we marked identical peaks of soil minerals, unhydrated cement clinker minerals and hydrated newgrowths. In the result of differential thermal analysis, we determined that soil cement with complex additive is characterized by the smaller amount of free calcium hydroxide formed, as well as saturation of the soil complex with sodium ions. In the soil cement sample with complex additive, we observe a smaller amount of coagulated soil aggregates in comparison with the sample without an additive. Complex additive contributes to the formation of a more dense and uniform structure of soil cement, reduces the amount of adsorption water associated with clay minerals, reduces the formation of free calcium hydroxide, which increases the physicomechanical properties of the resulting material.

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