Moisture intrusion into the subgrade can significantly increase its moisture content, leading to a decrease in stiffness and strength, thereby compromising the serviceability performance of the pavement. Electro-osmosis has been used as an effective method for reducing moisture content and improving subgrade mechanical properties. However, its impact on mechanical properties has not been well understood. This study evaluated the mechanical behavior of electro-osmosis-treated subgrade soil through laboratory experiments that included bender element and cyclic triaxial tests. The study analyzed the effects of supply voltage and soil compaction degree on electro-osmosis treatment. The results showed that after treatment, the shear wave velocity increased by 26.0 to 59.2%, and the dynamic resilient modulus improved by a factor of three. Increasing the supply voltage and degree of compaction was found to lead to more significant improvements. Further analysis revealed that the reduction in moisture content alone was insufficient to contribute to the improvement. Cementation of colloids generated by the electrochemical reaction between soil particles also contributed to the improvement. It is worth noting that the nonuniform distribution of moisture and colloid in electro-osmosis-treated soils resulted in heterogeneity, with soil close to the anode being the weakest in terms of mechanical strength. Chemical injection or polarity reversal was suggested to enhance the uniformity of distribution and improve the overall treatment effectiveness. Overall, the study highlights the potential of electro-osmosis as a viable method for improving the mechanical properties of subgrade soil, but further research is required to investigate the heterogeneity of the distribution of moisture and colloid.
