Enhancing Lime Dosage Determination for Lean Clay Soil Improvement: Significance of Plasticity Limit and Interpretation Approach

Enhancing the engineering properties of clayey soils is crucial for improving their performance in construction projects. Determining the optimal lime dosage using the Chemical Fixation Point (CFP) concept presents challenges due to soil variability, interactions with chemical and organic components, and limitations in environmental or equipment conditions, especially in pH-based methods. These challenges are exacerbated when non-standard lime or lime residues replace conventional lime. This study highlights the plasticity limit as a key parameter for optimizing lime dosage and assessing treatment effectiveness with lime residues. By analyzing four lean clay soils through CFP tests, plasticity limit measurements, and resistance evaluations, an improved methodology for CFP determination using pH–dosage curves is proposed. The findings validate the feasibility of lime residues, emphasize the plasticity limit’s critical role in lean clay treatment, and extend its relevance to soil stabilization. This work enhances CFP test accuracy and supports sustainable, adaptable soil improvement strategies.