Synergistic effects of colloidal nanosilica and fiber on the hydromechanical performance of mudstone soil in Taiwan

Abstract

Mudstone soils (MS) are widely distributed in southern Taiwan and have an inherent proclivity to geological damages and failures. However, the use of traditional and non-traditional techniques to treat MS remains a challenge and is an area relatively unexplored due to the soils’ distinct and sophisticated features. This study examined the hydromechanical performance of reconstituted MS treated with colloidal nanosilica (CN), fiber (f), and combinations thereof (CN-f) via a series of laboratory tests, including the unconfined compressive strength tests, 3D volumetric shrinkage tests, free swell tests, 1D consolidation tests, and filter paper tests. Fourier-transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) were also used to inspect the geochemical composition and microstructure of the untreated and treated MS. Results suggest that CN-f treatment can significantly improve the peak and postpeak strengths and ductility of MS while achieving satisfactory improvements in swelling control, shrinkage limits, and volumetric strains. Following treatment with 15% CN and 1% f for 28 days, the MS showed an optimal 527% improvement in Unconfined compressive strength (UCS) and satisfactory residual strain. Finally, the FTIR and SEM images revealed enhanced interlocking between the MS particles and the formation of marginal C–S–H and viscous gels, supporting the improved performance in MS. This study provides comprehensive analyses that offer insights into the synergistic effects of CN-f on the hydromechanical performance of MS. The findings will be valuable to engineers exploring innovative and ecofriendly alternatives for treating MS with a robust design.