Soil stability is crucial for construction, traditionally achieved with cement, lime, and fly ash. However, challenges with weak subgrade soils have led to nanomaterials as a promising alternative. This review critically evaluates the application of nanomaterials in improving the physicochemical, mechanical, and microscopic properties of subgrade and underlying soils, based on 136 peer-reviewed studies published between 2002 and 2025. Eighteen nanomaterials were identified, with nano-silica being the most studied. Other notable ones include nano-clay, carbon nanotubes, nano-alumina, nano-magnesium oxide, nano-copper, and polymeric nanomaterials. The review reveals a predominant focus on fine-grained problematic soils, particularly soft clay and silty sand, primarily in research from Iran. Nanomaterials improved soil by reducing plasticity, enhancing compaction, boosting strength (unconfined compressive strength, California Bearing Ratio, shear strength), and lowering permeability through void-filling, pozzolanic reactions, and Calcium Silicate Hydrate gel formation. They also increased durability under freeze-thaw and wet-dry cycles while reducing cement usage. However, concerns remain about cost, scalability, and environmental safety, with gaps in field-scale studies and limited research on nano-ZnO, nano-CuO, and nano-graphene oxide. This review serves as a reference for sustainable geotechnical engineering.

来源平台：ROAD MATERIALS AND PAVEMENT DESIGN