Technological factors of complex-modified strengthened soils for road construction

The object of research is the technological factors of complex-modified strengthened clay soils used in the construction of structural layers of road pavements. Method. The research method involves determining the influence of technological factors used in constructing structural layers of road pavements made from complex-modified, strengthened clay soils on changes in the following physical and mechanical properties: compressive strength, flexural tensile strength, and frost resistance coefficient. A second-order rotatable design of experiments was used to determine the recommended compositions of complex-modified reinforced soils. The article examines technological factors influencing the quality of soil strengthening technology in road construction, its operational properties, and the service life of road pavements. These factors include the order of introducing components into the soil (water, binder, modifiers), the size of soil aggregates present in the strengthened soil, the compaction coefficient and moisture content, and the duration of the technological process for constructing structural layers of road pavements. Results. It has been determined that the most effective method for applying the «Complex Modification» method to strengthened soils is moistening clayey soils before and after the introduction of a binder. Dependencies have been established for a significant increase (by 3.0−5.0 times) in the physical and mechanical properties of strengthened clayey soils of different particle size distributions when using the «Complex Modification» method. It has been established that complex modification makes it possible to level out the negative impact of insufficient compaction of strengthened clayey soils during the construction of pavement layers. With compaction factors from 0.98 to 0.94, modification increases the physical and mechanical properties by 2.3−4.0 times. The effect of the duration of the technological process on the physical and mechanical properties of complex-modified reinforced soils, in comparison with unmodified ones, has been determined. It has been established that the use of the «Complex Modification» method in industrial settings allows for a two- to three-fold increase in process time (up to 3.0 hours) compared to soil strengthened without modification. The results on the influence of technological factors on changes in the physical and mechanical properties of reinforced soils indicate that the use of modification methods contributes to improved manufacturability of road pavement structural layers and is an effective approach to improving soil-strengthening technology in road construction.