Enhancing the flexural performance of cement-treated laterite with geogrid reinforcement for base layer applications

This study evaluated the flexural behavior of cement-treated lateritic soil (CTL) reinforced with uniaxial and triaxial geogrids for use as a base layer. Thirteen CTL beam specimens were tested under four-point bending to assess the effects of geogrid type, tensile strength, stiffness, and reinforcement configuration. The unreinforced control specimen exhibited brittle failure with a peak flexural strength of 1.21 MPa. Reinforced specimens demonstrated substantial performance enhancements, particularly in double-layer configurations using high-strength or high-stiffness geogrids. Double-layer triaxial reinforcement with high radial stiffness achieved the highest peak strength of 1.52 MPa, while double-layer uniaxial reinforcement with high tensile capacity reached 1.46 MPa. The highest toughness ratio was 28, and the ductility index reached 29, reflecting significant post-crack energy absorption. Crack area was reduced by up to 82% in specimens with high-stiffness triaxial reinforcement. Scanning electron microscopy revealed dense bonding and strong interfacial contact in triaxial-reinforced composites. Additionally, the cost–performance analysis showed that RE560 in a single-layer configuration offers the most economical reinforcement, delivering the highest toughness improvement per unit installation cost. This highlights the need to balance mechanical performance with construction efficiency when selecting geogrid types for CTL base applications.