The effect of modification of asphalt concrete mixtures of different grain sizes with “Ric-Polycell” (Ukraine) and “Duroflex®-SMA” thermoplastic polymers (Germany), which were added directly to the asphalt mixer during their preparation, on the properties of asphalt concrete was studied. It is confirmed that it is more expedient to use stone mastic asphalt concretes with a larger size of mineral crushed stone grains on high-traffic roads, as they are more rutting-resistant compared to asphalt concretes with smaller size and content of crushed stone grains. The effect of the temperature of preparation and thermostating of asphalt concrete mixtures modified with the investigated thermoplastics on the compressive strength of asphalt concrete at a temperature of 50 °С, which were made of the studied mixtures, was investigated. It was found that the maximum possible temperatures of preparation and thermostating of asphalt concrete mixes provide a more complete modification. The effect of the content of thermoplastic polymers in the composition of asphalt concrete mixtures on the properties and rutting resistance of fine-grained asphalt concrete, as well as stone mastic asphalt concrete, was studied. It was found that adding the “Ric-Polycell” polymer in the amount of 1.5 % and 3 % by weight of bitumen in the composition of the studied asphalt mixtures in the asphalt mixer during their preparation increases the rutting resistance of asphalt concrete under the studied conditions by 2.52–3.86 times. Modification of asphalt concrete mixtures with the “Duroflex®-SMA” additive in the amount of 0.3 % and 0.6 % by weight of the aggregate by a similar technology also allows increasing the rutting resistance of the obtained asphalt concrete by 1.86–3.16 times. Using these modifiers in the future will have a positive effect on the service life of the entire pavement structure

Through a series of experimental studies on the unconfined compressive strength, indirect tensile strength (ITS) and freeze-thaw stability of cylindrical specimens, the feasibility of cement-stabilized iron tailings for semi-rigid bases in road construction is determined.Three variables, including the genesis of the materials from which cement stabilized macadam (CSM) are composed, the granulometric composition of the mineral part and the content of cement, were taken as influencing factors. The experimental study shows that with the increase of cement content, the unconfined compressive strength (UCS) , indirect tensile strength (ITS) and frost resistance all increase. Studies have shown that the content of coarse aggregate affects the strength properties and frost resistance of cement-stabilized macadam materials.

With the rapid development of ferrous metallurgy, the production of iron tailings as waste after beneficiation is increasing. Due to the shortage of natural stone in road construction, iron tailings can be used as an alternative material to natural stone in semi-rigid bases. In order to study the feasibility of application of cement stabilized iron tailings (CSIT) in semi-rigid base, unconfined compressive strength (UCS), indirect tensile strength (ITS) and cyclic freeze-thaw tests were carried out on cement stabilized iron tailings (CSIT). The gradation composition and cement content were selected as influencing factors. The results show that under the condition of the same cement content, the UCS and ITS of CSIT are proportional to the particle size in the mixture. In CSIT with the same gradation, the mechanical properties increase with the increase of cement content; CSM-40(B) has a higher UCS and CSM-40(C) has a higher ITS, the frost resistance coefficient of CSIT increases with the increase of cement content and the tendency of frost resistance coefficient decreases with the increase of cement content. The frost resistanceofCSM-40 (B) is better than that of CSM-40 (C) for the same cement content. Therefore, for the use of iron tailings in CSM, a suitable gradation composition and cement content should be selected.

To produce cationic bitumen emulsions, bitumen is used, whose penetration is not lower than 90 mm-1. Such bitumen has a small plasticity interval, which leads to a deterioration in its heat resistance at elevated temperatures and narrows the scope of application of emulsions based on it. Based on the review of emulsion modification methods, the modification has been proposed that involves mixing the finished bitumen emulsions with aqueous cationic latex. The process of interaction between a bituminous emulsion and an aqueous cationic latex has been considered. A mechanism for the disintegration of the modified bitumen emulsion on the surface of mineral materials was proposed. The emulsifiers have been selected and the composition of the aqueous phase has been chosen based on the analysis of surface tension isotherms. The influence of the modification on the properties of bitumen emulsions was investigated. It was established that the main physicochemical characteristics of the interphase surface accept similar values for the aqueous phase and emulsions based on it. It has been proven that the introduction of aqueous cationic latex quite moderately affects the basic physical-mechanical properties of emulsions, which makes it possible not to change the main technological parameters when using them. It was established that increasing the concentration of the polymer in the emulsion has a positive effect on the physical-mechanical properties of the binder. With an increase in the concentration of the polymer to 6 % the softening temperature increases by 16 °C, elasticity is 74 %, and the holding capacity at minus 25 °C is approaching 100 %. Improving the physical-mechanical properties of residual binder as a result of emulsion modification could increase the durability of layers in a roadbed based on bitumen emulsions and expand the scope of their application in the construction and repair of motorways