In cold regions, and considering the increasing concerns regarding climate change, it is crucial to assess soil stabilisation techniques under adverse environmental conditions. The study addresses the challenge of forecasting geotechnical properties of lime-stabilised clayey soils subjected to freeze-thaw conditions. A model is proposed to accurately predict the unconfined compressive strength (UCS) of lime-stabilised clayey soils exposed to freeze-thaw cycles. As the prediction of UCS is essential in construction engineering, the use of the model is a viable early-phase alternative to time-consuming laboratory testing procedures. This research aims to propose a robust predictive model using readily accessible soil parameters. A comprehensive statistical model for predicting UCS was developed and validated using data sourced from the scientific literature. An extensive parametric analysis was conducted to assess the predictive performance of the developed model. The findings underscore the capability of statistical models to predict UCS of stabilised soils demonstrating their valuable contribution to this area of study.

The construction of high-speed railway in Southwest China must traverse extensive regions of red mudstone. However, due to the humid subtropical monsoon climate in Southwest region, the red mudstone is often exposed to a high-water content or saturated state for extended time, and the poor mechanical properties under such condition cannot satisfy the requirements of high-speed railway subgrade. This paper proposes the use of lime and cement to improve the saturated unconfined compression strength (UCS) of the red mudstone fill material. Comprehensive tests, including UCS tests and scanning electron microscopy, were conducted on cement-lime modified red mudstone. Results show that lime stabilisation can significantly enhance the UCS and elastic modulus with the increase of dry density and modifier content. For the specimens with 4% lime and 6% cement, both peak strength and elastic modulus of the modified samples are more than 10 times higher than those of the untreated ones. The modulus exhibits nonlinear degradation with the development of shear stress, but the degradation can be improved with the increase of dry density and modifier content. At 60% of initial tangent modulus, the corresponding stress for untreated soil, lime stabilised and cement-lime modified filler are 0.74, 0.92 and 0.99. As for the energy evolution, the increasing dry density can enhance elastic and dissipated energies through denser particle arrangements, while a higher modifier content raises total energy. When the cement content is 6%, the total energy is more than 8 times higher than that of the untreated material, reflecting increased brittleness to a sudden fracture. The improvements are attributed to the formation of acicular and platy hydration products, which can tighten the pore structure. The study underscores the importance of lime and cement in ensuring subgrade stability for high-speed railways in Southwest China's red bed regions.

Presence of sulphates in lime-stabilised soils can lead to a reduction in long term strength, which can have adverse effects on construction and engineering projects. The present study focuses on addressing the challenges posed by sulphate content in lime-stabilised Kuttanad marine clays. By introducing 6% lime and 4% sulphates (sodium sulphate and lithium sulphate) to untreated clay, the research aims to investigate the effect of sulphates in these clays. To mitigate sulphate-related issue, barium hydroxide, in both its pure laboratory form and the commercial variant baryta, was employed to develop an effective mitigation strategy for strength reduction. Unconfined compression tests were conducted on lime-treated clay both with and without additives, immediately after preparation and over 1 week, 1 month, 3 months, 6 months, 1 year and 2 years of curing. Test results indicated that both sodium sulphate and lithium sulphate negatively impact the strength gain of lime-stabilised clay, with lithium sulphate having a more detrimental effect. There was a consistent improvement in shear strength with the addition of both barium hydroxide and baryta. The results of SEM and XRD analysis also align with the above findings. When twice the predetermined quantity of baryta was added, it outperformed pure barium hydroxide in terms of shear strength enhancement. The cost-effective nature of baryta, being a mere quarter of the price of pure barium hydroxide, makes it a viable alternative for addressing the strength loss in lime-stabilised sulphate bearing Kuttanad marine clays.

The utilisation of red mudstone waste as subgrade fill material after lime stabilization can meet the requirements of green development. This study aims at investigating the lime stabilization effect on the changes in mechanical properties and microstructure of compacted red mudstone fill material, with particular emphasis on the curing time effect. Red mudstone fill material were stabilized by 4 % lime, and the unconfined compressive strength, direct shear strength and microstructure of the lime-stabilized fill material specimens were determined at various curing times. Results show that the lime stabilization can significantly improve the unconfined compressive strength, modulus and direct shear strength and effectively mitigate the water sensitivity of the red mudstone fill material. The density function curve of the saturated red mudstone fill material shows monomodal characteristic, but the saturated lime stabilized fill material still maintains bimodal characteristic even with only one day of curing. The microstructure modification induced by lime stabilization mainly results from the rapid flocculation of soil particles and the formation of hydration product. During curing, the percentage of the nano-pores increases, mainly attributes to the formation of C-A-S-H which fills the micro-pores gradually.