Eco-friendly approach to clay stabilization: Integrating carbide lime, steel slag, and tire textile waste
Parisa Heirani, Sina Mahmoudi, Mohammad Mahdi Shalchian, Payam Zanganeh Ranjbar, Mahyar Arabani, Mahdi Salimi, Meghdad Payan
Abstract
Expansive clay soils are prone to deterioration under Freeze-Thaw (F-T) cycles due to volumetric instability. This study evaluates a stabilization approach using Carbide Lime (CL), Electric Arc Furnace (EAF) slag, and Waste Tire Textile Fibers (WTTFs). Soil samples with varying CL (5–30%), EAF slag (5–20%), and WTTF (0.5–2%) contents were cured for 7, 28, and 56 days. Mechanical and durability performance was assessed through Unconfined Compressive Strength (UCS), Indirect Tensile Strength (ITS), Ultrasonic Pulse Velocity (UPV), and F-T cycling, supported by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy-Dispersive Spectroscopy (EDS) analyses. The optimum mix of 25% CL and 10% EAF slag achieved a UCS of 8,254 kPa after 56 days. Adding 1.5% WTTFs further increased the UCS to 10,255 kPa, the UPV to 2,197 m/s, and the ITS to 1,650 kPa. Stabilized soils maintained higher strength and reduced degradation after 8 F-T cycles compared with untreated soil. Microstructural results confirmed the formation of Calcium-Silicate-Hydrate (C-S-H) gels and other cementitious phases. The combined use of CL, EAF slag, and WTTFs offers an alternative method for improving the mechanical and durability properties of expansive clays in cold climates.