The paper presents an assessment of the effectiveness of the use soil-cement with hydrophobized surface by conducting a feasibility study. The work performed theoretical studies and the calculation part. The object of study is a soil-cement with hydrophobized surface at the base in road foundation of the road. The subject of the study is the economic efficiency of the use of modified soil-cement. Theoretical studies are based on the choice of methodology for assessing the economic efficiency of the use of this material with its subsequent description. The calculation part includes determining the benefits of road users, current and one-time costs from the use of various constructions of pavement for the billing period. The result of the calculations is a graph of the dependence of the economic efficiency of various structures on traffic intensity. The use of soil-cement with hydrophobized surface will reduce economic costs in the construction of roads, increase the speed and quality of work, increase the overhaul time of roads of federal and regional significance.

The paper presents a complex method for increasing water resistance and reducing crack formation by using a prefabricated foundation of soil-cement slabs with surface processing with a hydrophobizing material on basis of organosilicon compounds. Theoretical, laboratory and full-scale experimental studies were made. Theoretical studies are based on the substantiation of the geometric parameters of the slab in order to exclude the probability of its destruction under its own weight during building and installation works. The result of the first stage of laboratory studies is the determination of the optimum composition of soil-cement mixture in order to achieve a grade of strength M20. At the second stage, the effectiveness of the influence of hydrophobizing materials "Tiprom U" and "Penetron-Admix" on water absorption and compressive strength of soil-cement was determined. The final stage of the research was a full-scale experiment. In the factory environment, soil-cement slabs were manufactured in metal forms. Based on the results of the research, conclusions about the effectiveness of this complex method were made. The use of soil-cement slabs allows reducing crack formation, as well as to work all year round due to manufacturing and surface treatment of slabs in the factory conditions.