Geogrids for Soil Reinforcement & Base Stabilization — Arizona

A geogrid is a stiff, open-grid polymer mesh that interlocks with aggregate particles pressed into and through its apertures. Once compacted, the aggregate can't shift laterally the way it would over unreinforced subgrade, so load spreads over a wider area of soft ground instead of punching straight down.

That mechanical interlock is different from a geotextile's separation function — a geogrid actively reinforces, which is why it shows up in the section itself rather than just at the soil-aggregate interface, though the two are often used together on soft subgrade.

Biaxial geogrids have equal rib strength in two perpendicular directions and are the standard choice for base reinforcement under roads, parking lots and pads carrying fairly uniform, multi-directional traffic. Triaxial geogrids add a third rib direction, distributing load more efficiently in all directions and are commonly specified for unpaved and lightly paved roads, access roads and haul routes over weak subgrade, where they typically allow a thinner aggregate section than biaxial for the same design traffic.

• Biaxial geogrid — parking lots, pads, paved roads with uniform traffic
• Triaxial geogrid — unpaved and haul roads, weak or variable subgrade
• Subgrade improvement over soft or expansive soils
• Base course stabilization to reduce aggregate thickness

Selection is driven by subgrade strength (CBR or soaked resilient modulus), design traffic, and target section thickness. Weaker subgrade and heavier or more channelized traffic generally point toward triaxial grid and/or a combined geotextile-geogrid system; stronger subgrade with lighter, distributed traffic may only need biaxial grid or none at all.

Arizona's expansive clay pockets and caliche layers change the math from a generic table — a soil that looks firm dry can lose most of its bearing strength when saturated during monsoon season, which is exactly when a thin, unreinforced base section fails. We size grid type and base thickness to your actual geotech report and design traffic, and every recommendation should be confirmed against project-specific specs with the engineer of record.

• Get a soil report — CBR or resilient modulus drives grid selection
• Match grid type to design traffic and expected saturation
• Consider a combined geotextile + geogrid section on soft, fine-grained subgrade
• Confirm final section with the engineer of record before construction

Installation places the geogrid directly on prepared, proof-rolled subgrade, rolled out with manufacturer-specified overlap, pinned or tensioned flat, then covered with the first aggregate lift and compacted without turning equipment directly on the exposed grid. Correct overlap and lift thickness on the first pass matter more than anything downstream — get those wrong and the interlock never develops properly.

Manufacturers report that properly designed geogrid-reinforced sections can extend pavement service life or allow meaningfully thinner base sections compared with unreinforced designs; treat specific percentage claims as manufacturer-stated and confirm the design section with your engineer. We supply grid by the roll for your crew or install complete reinforced base sections as part of a grading and paving scope.