Effect of glass fiber (GF) on the mechanical properties and freeze-thaw (F-T) durability of lime-nanoclay (NC)-stabilized marl clayey soil

Marl clays with varying levels of calcite content often exhibit more erratic behavior compared to other problematic soils, especially when exposed to repetitive Freeze-Thaw (F-T) cycles. It is crucial to prioritize the mechanical properties and durability of this particular soil variety as neglecting such characteristics can result in irreversible harm to the superstructures. This research focused on examining the utilization of lime and Nanoclay (NC) as stabilizers and Glass Fiber (GF) as reinforcement for natural marl soil. The study involved preparing samples with 6% lime and up to 1.5% NC, combined with varying amounts of GF ranging from 0 to 1%. The samples were cured for 7 and 28 days and subjected to 0, 1, 4, and 8 F-T cycles. Several Unconfined Compressive Strength (UCS) and Indirect Tensile Strength (ITS) tests as well as microstructural analyses including Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) were performed on the samples before and after being exposed to F-T cycles. Results showed that the application of GF enhanced the UCS and ITS of lime-NC-stabilized marl soil by creating interlocking zones between the particles. The addition of lime and NC shifted the behavior of the soil sample from ductile to brittle, while the inclusion of GF caused the soil to revert to ductile behavior, resulting in a decrease in secant modulus (E50) and an increase in energy absorption capacity (Eu) compared to samples without GF. Furthermore, incorporating GF along with lime and NC into the marl soil improved the F-T durability even after 8 cycles and resulted in reduced strength deterioration compared to the control sample. The optimum mixture was found to be 6% lime, 1% NC, and 0.75% GF, resulting in a noteworthy improvement of 6.5 times in the ITS and a slight decrease of 6% after 8 F-T cycles compared to the untreated marl soil.