Freeze-thaw durability of clayey soils stabilized by alkaline-activated kaolin and recycled cement kiln dust
Razan AlFukaha, Fathi Shaqour, Muhannad Ismeik
Abstract
• Weak soils present challenges for infrastructure construction, especially when subjected to frost action. • Durability and UCS of soils stabilized with kaolin (10, 25, and 50 %) and CKD (10 %) are experimentally studied under 5, 10, and 20 F-T cycles at various curing temperatures (40, 60, and 80 °C) and durations (1, 7, 14, and 28 days). • F-T cycling reduces the durability and UCS of unstabilized natural soils, with this effect becoming more pronounced as the number of cycles increases; however, the addition of a stabilizer mitigates this problem. • Improvement of UCS in weak natural soil depends on type and content of additive used, curing duration, and temperature. • Clays stabilized with kaolin (50 %) or CKD (10 %) can effectively enhance base/subbase layers for pavement facilities and improve the bearing capacity of shallow foundations in cold regions, resulting in economic and sustainability benefits for the earthwork construction industry. Weak soils pose significant challenges for civil engineering projects, particularly in cold regions. Stabilizing such soils with additives is a common practice to enhance their geotechnical properties. This research aimed to evaluate the durability of clayey soils stabilized by alkaline-activated kaolin at 10, 25, and 50 %, along with 10 % recycled cement kiln dust (CKD). The stabilization process involved curing the soils at different temperatures (40, 60, and 80 °C) for varying durations (1, 7, 14, and 28 days). The stabilized soils underwent 5, 10, and 20 freeze-thaw(F-T) cycles to evaluate their durability. The results indicated F-T cycling led to a reduction in the unconfined compressive strength (UCS) of unstabilized soils, with a more pronounced impact as the number of F-T cycles increased. However, this adverse effect was mitigated by additive stabilization. The improvement in UCS in stabilized soils was directly linked to the additive content, curing duration, and temperature. Both additives demonstrated superior resistance to F-T cycling, with CKD outperforming kaolin. Study findings provided guidelines for utilizing kaolin and CKD for earthwork applications in cold regions with economic and sustainability advantages.