## 3 Consolidation Properties
### Effects of Line-Cement Stabilization on the Preconsolidation Stress of the Clay Soil  
Preconsolidation stress, representing the maximum effective stress a soil has experienced and critical for foundation design and slope stability analysis, increased dramatically from 355.63 kPa at 0% additives to a peak of 1088.92 kPa at 6% cement and 15% lime content through complex physicochemical mechanisms (Figure 7). This 206% enhancement results from calcium hydroxide initiating pozzolanic reactions that generate calcium silicate hydrate and calcium aluminate hydrate gels, creating robust inter-particle bonds and a complex microstructural network that significantly enhances soil skeleton stiffness and load-bearing capacity. The optimal combination at 15% lime demonstrates the critical balance required for maximum consolidation resistance, as further lime increases beyond this threshold, particularly at 8% cement, result in slightly lower preconsolidation stress values due to potential saturation where excess binding agents disrupt the optimal crystalline gel structure. This transformation fundamentally alters the soil's mechanical history by creating artificial overconsolidation through chemical bonding rather than physical loading, effectively increasing the soil's apparent geological stress experience and making it more suitable for construction applications requiring enhanced bearing capacity and reduced settlement potential. The relatively high preconsolidation stress of 355.63 kPa reflects the clay's overconsolidated nature, likely from past overburden removal through erosion. The deposit was initially subjected to greater effective stresses from overlying formations that were subsequently eroded, while preserving the consolidated fabric established under higher stress conditions. The montmorillonite-dominated mineralogy suggests marine or lac  
Figure 7: Preconsolidation stress variations with cement content (0-8%) across different lime percentages (0-30%). accumulating sediment thickness generated consolidation pressures significantly higher than current overburden stress, developing strong inter-particle bonds and reduced void ratio. Subsequent geological processes including tectonic uplift, glacial cycles, or erosional events removed substantial overburden while maintaining the consolidated structure. The high plasticity index (42%) and liquid limit (66%) are consistent with overconsolidated marine clays that experienced significant stress history, reflecting previous consolidation influence on structural arrangement. Alternative explanations include desiccation effects from past climatic conditions or secondary compression over extended periods enhancing recompression resistance. The preconsolidation pressure magnitude aligns with typical values for overconsolidated clays in similar geological settings, indicating that stress history significantly influences mechanical behavior and explains the substantial baseline strength observed before stabilization treatment. The pre-consolidation stress values in clay soil stabilization using industrial by-products like bagasse ash (BA) and poly(vinyl alcohol) (PVA) exhibit distinct trends. For bagasse ash and lime, studies by [PERSON], [PERSON] [38] show that combining it with lime significantly enhances pre-consolidation pressure. For instance, a mixture of 18.75% BA and 6.25% lime reduced swelling pressure and increased pre-consolidation stress, with the highest values observed in this ratio. Similarly, sugarcane bagasse ash (SCBA) improved preconsolidation pressure (\(\sigma\)'c) over curing periods, alongside reduced compressibility indices (C\(\alpha\)/Cc) as per [PERSON], [PERSON] [39]. These effects are attributed to pozzolanic reactions and microstructural bonding, akin to lime-cement systems but with lower efficacy in stress improvement compared to the increase observed in lime-cement stabilization.