Dispersive clay is widely distributed in the Songnen Plain of northeast China, causing serious embankment damage to hydraulic engineering, and the research on the relevant failure mechanism is still incomplete. In this study, based on the real stress path of dispersive clay failure, a mechanical experimental method under plane strain conditions was adopted to investigate the strength properties of dispersive clay. The results showed that under plane strain conditions, the stress-strain curve of dispersive clay exhibited the strain hardening type, distincted from the conventional strain softening type under triaxial vertical conditions, and the strength difference was approximately twice at a consolidation stress of 50 kPa. The stress-strain relationship of the principal stress also showed the strain hardening type, and the relationship between the stress-strain was approximately linear. Under low consolidation stress, the coefficient of the intermediate principal stress reached 0.44, indicated a significant influence of the intermediate principal stress on the strength of the clay. Under low consolidation stress, the failure mode of dispersive clay was characterized by swelling with no obvious spatial shear band, while under high consolidation stress, the failure mode exhibited a shear band located diagonally. Additionally, the strength properties of dispersive clay were weakened by the leaching of chemical ions in the clay, showed different compaction and strength under different consolidation stresses.

Dispersivity has long been a major concern in civil and geo-environmental engineering, as well as in agricultural engineering and soil sciences. Dispersive clay soils are common, but their prevalence and characteristics vary greatly across different regions of the world, especially in arid and semi-arid areas. These soils are highly unstable and prone to erosion when exposed to water, due to their high concentration of exchangeable sodium ions and large specific surfaces. This can cause serious damage to hydraulic infrastructure. However, identifying and stabilizing dispersive clay soils is crucial for infrastructure projects, as the use of untreated soils can result in irreversible and catastrophic failures due to internal erosion and piping. The systematic management of dispersive clays is crucial to prevent the wastage of fertile agricultural land and land designated for engineering construction. Although industrialization has numerous benefits, it often results in large quantities of waste byproducts that must be managed appropriately to reduce their environmental impact. The reuse of these wastes in soil improvement has become an increasingly popular approach to address both environmental pollution and cost-effectiveness concerns. Despite the growing interest in using waste by-products for soil stabilization, there is a lack of a systematic and comprehensive review of the management, mechanisms, identification systems, and improvement strategies for both traditional and non-traditional stabilizers. Therefore, there is an urgent need to review the available literature to provide a comprehensive understanding of the use of waste by-products for soil stabilization. Such a review could aid in the creation of soil stabilization methods that are both efficient and enduring while minimizing the environmental impact of waste by-products.

Dispersion occurs when clay soil disperses under specific conditions and is rapidly washed away. While there are numerous methods for rectifying it, they are neither cost nor time-effective. The current study used metakaolin and zeolite to improve heavily dispersive clay soil either separately or in combination at 0%, 2%, 4%, 6%, and 8% of the soil weight. After 7 days of curing, the samples were tested to determine the extent of change in the dispersion potential, as well as the improvement of the geotechnical properties of the soil. The results indicated that the addition of 2% zeolite with 6% to 8% metakaolin decreased the dispersion potential considerably. Double hydrometry test findings revealed that the dispersion potential decreased by almost 70% and entered the non-dispersive group; the crumb test also revealed this. Atterberg limits testing indicated a decrease in the plasticity index which reduced the flexibility of the samples. The greatest decrease in PI (67.5%) was achieved with the addition of 8% zeolite plus 8% metakaolin to the soil. The results of density tests revealed that a decrease in the optimal moisture content increased the maximum dry density of soil. This increase in density was a response to the high reactivity of metakaolin with calcium hydroxide and the formation of calcium hydroxide hydrate gel. This eventually caused an increase in the unconfined compressive strength, the greatest increase in strength of about 1.8-fold was observed with a combination of 2% zeolite and 6% metakaolin compared to the unmodified sample.