Multi-scale performance of geogrid-reinforced cemented sand as a composite base material

This study investigates the flexural performance and reinforcement mechanisms of geogrid-reinforced cemented sand, focusing on the effects of geogrid type (uniaxial vs. triaxial) and layer configuration (single vs. double). A comprehensive experimental program was conducted, including four-point bending, pullout testing, digital image analysis, strain measurement, and SEM observation to evaluate mechanical behavior, crack control, interfacial interaction, and microstructure. The results show that triaxial geogrids outperform uniaxial systems, particularly in double-layer configurations. The double-layer triaxial system achieved the highest performance, with an improved strength ratio (ISR) of 2.10, a toughness improvement ratio (ITR) of 34%, and a crack-reduction ratio (Rcr) of 93%. Strain measurements (0.47%–0.86%) indicate a more uniform stress distribution and effective load transfer. Although uniaxial geogrids exhibited higher peak pullout resistance, they showed more brittle behavior, whereas triaxial geogrids demonstrated improved ductility and post-peak performance. SEM analysis confirmed enhanced interfacial bonding and more efficient stress dispersion in triaxial systems. Overall, the findings highlight the superior performance of double-layer triaxial configurations and provide practical guidance for designing durable cemented sand base materials.