Effect of water during freeze-thaw cycles on the performance and durability of lime-treated gypseous soil

- Water content of soil is a key parameter of the stability of earth structures during F-T.
- Increasing water content in lime-treated gypseous soil modifies physicochemical properties.
- Optimal % of added lime enhances the performance of gypseous soil against F-T cycles.
- Gypseous soil should be protected from any water infiltration during F-T cycles.

Research on the freeze-thaw durability of soils in general and on the variation in moisture conditions in particular is vital for both economic and stability reasons. The present study is an attempt to further understand the process of freeze-thaw deterioration under two different test procedures (an open system with water uptake during thawing and a closed system with only initial water content), by measuring the strength, gas permeability, mineralogical, and microstructural properties of lime-treated gypseous soil. The study involved fine-grained soil with different gypsum contents (0%, 5%, 15%, and 25%) of soil dry weight. The soil samples were treated with 3% lime and cured for 28 days at 20 °C, then subjected to 12 freeze-thaw cycles in both open and closed systems, following the ASTM test procedure. A detailed parametric study (laboratory study) was conducted in order to understand the behavior of these soils. Results show that the tested characteristics of the soil samples depended considerably on the water available during the freeze-thaw procedure and on the gypsum content. Unconfined compressive strength decreased and gas permeability increased with increasing gypsum content and number of freeze-thaw cycles. The water content of the soil samples is a key parameter of the stability of earth structures under freeze-thaw conditions.