Colloidal silica (CS) is gaining attention as a novel, low-carbon binder with unique physicochemical properties that offer a sustainable alternative to conventional soil stabilisers. Its nanoscale particle size, chemical stability, and gelation capabilities make it particularly promising for geotechnical applications. This study examines the potential of CS for ground improvement, with a specific focus on sand stabilisation. Experimental investigations, including gelling time measurements and unconfined compressive strength (UCS) tests, were conducted to assess the gelation behaviour of CS and its effect on the mechanical performance of treated sand. Results indicate that CS treatment leads to a marked improvement in UCS, demonstrating its ability to enhance soil strength through particle bonding and pore-space filling. The findings underscore the potential of CS as an innovative binder for soil stabilisation and grouting, offering an environmentally friendly solution with a reduced carbon footprint.