Soil stabilization is widely applied in transportation engineering to enhance the mechanical performance and serviceability of road subgrades, particularly in fine-grained soils susceptible to moisture-induced deterioration. Although Portland cement provides rapid strength development and high load-bearing capacity, its high energy consumption and associated CO2 emissions have encouraged the exploration of lower-impact stabilization alternatives. This study presents a performance-based comparative evaluation of fine-grained soils stabilized with Portland cement and kaolin at dosages of 3%, 5%, and 7% by dry soil mass. The experimental program included soil characterization, Standard Proctor compaction testing, and unconfined compressive strength (UCS) testing conducted at curing ages of 0, 7, 14, 28, 90, and 180 days. Cement-treated soils exhibited faster early-age strength development and higher long-term UCS values, supporting applications requiring early load-bearing capacity. In contrast, kaolin-treated soils showed gradual and stable strength gains primarily associated with densification and particle rearrangement mechanisms. Overall, the results demonstrate that kaolin can serve as a viable low-impact stabilizer for low-volume and secondary road infrastructure. The findings support performance-based and sustainability-oriented material selection strategies for context-sensitive road subgrade design.
González et al. (Wed,) studied this question.