Comprehensive Stabilization of Humus Soils for Road Construction: Efficient Trains Based on Industrial Waste

Statement of the problem. Humic (organomineral) soils with a high content of organic matter (humus) are unsuitable for direct use in road foundations due to low strength, high plasticity, water absorption, swelling and deformations. Traditional stabilization methods (cement, lime) are often ineffective due to the inhibitory effect of humic acids. The task is to develop cost-effective and technically sound methods for stabilizing humus soils that overcome the negative effects of organic matter. Results. The need for pretreatment with lime (2—4 %) has been established to neutralize humic acids and reduce plasticity (especially with humus >6 %). Effective complex stabilization formulations have been developed that combine chemical neutralization (lime, ash), formation of a mineral framework (cement, slag, fly ash + sand/crushed stone), hydrophobization and reinforcement (bitumen emulsions, polymers, fibers). Specific economical formulations based on industrial waste (fly ash, blast furnace slag, lignin, sawdust) and local materials (clay, sand, crushed stone) are proposed, allowing one to reduce the cost by 20—50 %. Clear recommendations have been developed on the choice of binders/additives depending on the properties of the soil (humus, clay, sand, pH, water absorption, shear strength). Conclusions. Successful stabilization of humus soils requires mandatory preliminary neutralization of organic matter. The greatest efficiency and cost-effectiveness are achieved by complex formulations combining different stabilization mechanisms (neutralization, carcassing, hydrophobization). The use of industrial waste (ash, slag, lignin) and local materials is the main way to significantly reduce production costs (20—50 %) while maintaining the required properties. A detailed analysis of the initial soil and strict adherence to technology (especially pretreatment with lime and compaction) are absolutely necessary for a guaranteed result. Further research should be aimed at in-depth mathematical modeling of processes and experimental verification of the proposed formulations in real conditions.