Abstract: This study addresses the problem of environmentally friendly technologies in the transport construction. The study presents 3 technologies based on the silica sol properties: sol-gel transition, formation of heavy metal silicate hydrates; absorption of sols by capillaries and pores in concrete. Silica sol improved the concrete properties by 20-90%. The thermodynamical method is suggested to understand the nature of such improvements. Soil strengthening and detoxification appear rather promising outcome of the suggested technologies. Findings of this study can be useful for the purposes of environmental protection, soil strengthening and quality improvement in the transport construction.