## 2 Materials and Method
### Specim Preparation
Cylindrical specimens (38 mm diameter \(\times\) 76 mm height) were compacted using a three-layer wet tamping method, with each layer receiving a controlled number of blows from a calibrated compaction hammer to achieve uniform density. Interlayer scarification was performed to enhance bonding and mitigate plane weaknesses. Environmental conditions (temperature, humidity) were stabilized throughout testing, and instrumentation--including load cells, displacement transducers, and data acquisition systems--underwent regular calibration to ensure measurement precision. This systematic approach yielded a robust dataset characterizing the influence of stabilizer type, dosage, and curing duration on soil strength, compressibility, and hydraulic behavior, providing a comprehensive framework for evaluating stabilization efficacy in clay soils. The cement used in this study was Ordinary Portland Cement (OPC) Type I conforming to ASTM C150 specifications, sourced from [Kofar Ruwa Market Kano State, Nigeria product from Dangote Cement Plc Kogi State, Nigeria]. The chemical composition presented in Table 2 shows typical characteristics of Type I Portland cement, with CaO content of 62.62% and appropriate levels of silicates and aluminates for standard construction applications. The lime used was commercial hydrated lime (calcium hydroxide) intended for construction purposes, though as noted in the chemical analysis, it exhibited lower purity than typical high-grade hydrated lime products. Based on the chemical composition showing CaO content of 50.5% and elevated loss on ignition (42.32%), this lime would be classified as lower-grade hydrated lime, likely affected by carbonation during storage. The lime was sourced from [Sabon Gari Market Kano State, Nigeria] and, while not meeting the strict requirements of ASTM C207 Type N hydrated lime (which typically requires minimum 95% Ca(OH)2\({}_{+}\) CaO content), it represents materials commonly available in many construction markets. The chemical composition analysis of lime and cement presented in Table 2 was conducted using standard analytical techniques for oxide quantification, including X-ray fluorescence (XRF) spectroscopy and wet chemical methods. The reported values for constituents such as SiO2, Al2O3, Fe2O3, CaO, and MgO align with typical compositional ranges for commercial Portland cement and hydrated lime. The loss on ignition (LOI) for lime (42.32%) reflects its calcitic origin and hydration state. These analyses adhered to established protocols for cement and lime characterization, such as ASTM C114-22 (standard test methods for chemical analysis of hydraulic cement) for cement and ASTM C25-22 (standard test methods for chemical analysis of limestone, quicklime, and hydrated lime) for lime. The mineralogical identification of montmorillonite as the dominant clay mineral in the soil was confirmed via X-ray diffraction (XRD) analysis, consistent with the methodology outlined in ASTM D3084-22 (standard practice for alpha-quartz content of soil). These standardized approaches ensure compatibility with global material characterization practices while maintaining precision for geotechnical applications. The CaO content of 50.5% and LOI of 42.32% indeed indicate significant deviation from pure Ca(OH)\({}_{2}\) characteristics. Pure calcium hydroxide theoretically contains approximately 75.7% CaO with LOI values typically ranging from 24 to 25%. The elevated LOI in our lime sample (42.32%) suggests extensive carbonation, likely indicating the conversion of Ca(OH)\({}_{2}\) to CaCO\({}_{3}\) through atmospheric CO\({}_{2}\) exposure during storage or handling. This lower purity could have influenced our experimental results by reducing the material's reactivity, as the carbonated fraction (CaCO\({}_{3}\)) is significantly less reactive than Ca(OH)\({}_{2}\) for soil stabilization.