The soil of the Guabirotuba geological formation (Paraná Basin, Brazil) has physico-mechanical properties which are not suitable for its utilization in pavement construction, in protection of hillsides and slopes, or as shallow foundation support. Treatment of this soil by lime addition would improve its usability. The present context intends to determine the ratio between the splitting tensile strength (qt) and the unconfined compressive strength (qu) of clayey soil in the metropolitan region of Curitiba City, which has been treated with different lime contents and curing times. The control parameters evaluated include lime content (L), curing time (t), moisture content (w), and ratio of porosity to volumetric lime content (η/Lv). It was observed that the qt/qu ratio is between 0.17 and 0.2 in relation to the curing time, and an exponential relation exists between them. Meanwhile, the unconfined compressive strength of lime-treated soil was found to be approximately four times the initial value.

This study investigates the performance of sustainable use of recycled-glass powder (GP) in soil improvement. The porosity/cement ratio ($\eta /C_{\mathrm{iv}}$ ) and curing time are employed to study the evolution of unconfined compressive strength (${\mathrm{q}}_{\mathrm{u}}$ ) and durability against wet–dry cycles (measuring of loss of mass) of a sedimentary silty soil of Guabirotuba formation, stabilized with GP and cement, in Southern Brazil. Three dry unit weights of molding (${\gamma }_{\mathrm{d}}$ ), three cement contents ($C$ ) between 3% and 9%, and curing times of 7, 28, and 90 days are used to study the influence of GP content (i.e., 5%, 15%, and 30% by weight) and $\eta /{\mathrm{C}}_{\mathrm{iv}}$ index on ${\mathrm{q}}_{\mathrm{u}}$ and accumulated loss of mass (ALM) of the compacted blends. The long-term strength improvement and durability are observed and well-fitted to a power function depending on the $\eta /{\mathrm{C}}_{\mathrm{iv}}$ ratio. When ${\gamma }_{\mathrm{d}}$ , GP, and $C$ are increased and the initial porosity ($\eta$ ) is reduced, ${\mathrm{q}}_{\mathrm{u}}$ strength and durability increase for all GP contents. The $\eta /{\mathrm{C}}_{\mathrm{iv}}$ ratio can also establish the empirical ratios between ${\mathrm{q}}_{\mathrm{u}}$ -ALM dependent on the GP contents used during compaction of the specimens. Finally, equations for dosing and estimating ${\mathrm{q}}_{\mathrm{u}}$ and ALM are obtained and set to 96.5% with a 6% error. Thus, all strengths and ALM percentages show the same normalized (i.e., divided) potential trend as the functions of GP, $C$ , and ${\gamma }_{\mathrm{d}}$ , compatible for the value of $\eta /{\mathrm{C}}_{\mathrm{iv}}^{0.20}=37.5\%$ by volume, and it may be possible to extend it to other compacted blends proposed in the recent literature, such as soil-lime and soil-cement-roof tile waste.

Fine-grained soils have a low load-bearing capacity that hinders their use in pavement construction, slope protection, or foundation support. Therefore, the chemical stabilization of a soil with the addition of lime is a viable technique that could enable its use in civil construction. Unconfined compressive strength (UCS) and split tensile strength tests were performed to evaluate the improvement of a soil with lime and the existing correlation between these two tests. This study aims to determine the empirical relationships between the split tensile strength ($q_t$ ) and UCS ($q_u$ ) of a silty soil artificially cemented with hydrated lime ($L$ ). To calculate the $q_t/q_u$ ratio, soil–lime specimens are molded by controlling the dry unit weight, lime content, porosity, and water content, followed by curing for 15, 30, 60, 90, and 180 days. The voids/lime relationship determined by the porosity/volumetric lime content ratio ($\eta /L_v$ ) plays an essential role in this study, and it is the principal parameter used to assess the increases in $q_t$ and $q_u$ and determine their empirical relationship. The results demonstrate that $q_t/q_u=0.16$ for all curing times (15–180 days), so that it is an overall constant relationship ($q_t/q_u$ ). Moreover, with the addition of 9% lime, maximum resistances of $q_t$ (700 kPa) and $q_u$ (3,750 kPa) are obtained for the soil–lime mixtures after 180 days of curing. Moreover, two dosage equations that can be used as mix design relationships are obtained to determine the $q_t$ and $q_u$ of the lime-treated soils.