North Carolina NCDOT Geotextile Fabrics

Solmax DOT Standard Specification Product Chart (click image to expand)

North Carolina NCDOT - Geotextile Uses

North Carolina projects cross Coastal Plain sands and marshes, red Piedmont clays, and steep Blue Ridge corridors. Add hurricanes, tropical downpours, flashy Piedmont streams, winter freeze–thaw, and heavy truck volumes on I-95 and I-40, and you get subgrades that can soften, pump fines, rut, scour, and settle. Geotextiles are the quiet engineering layer that helps pavements, structures, and drainage systems keep performing in these conditions.

Separation and stabilization. On new lanes, shoulder widenings, and rehab work, a woven geotextile is placed between native soil and granular base. It keeps fine soils—plastic clays in the Piedmont and loose sands near the coast—from migrating into aggregate under traffic, spreads load, and preserves base thickness. Where subgrades are very soft or saturated (tidal lowlands, floodplain approaches, and utility cuts), crews first roll out fabric to create a working platform so haul trucks and pavers don’t punch through. On exceptionally weak ground, fabric is often paired with a geogrid for added stiffness.

Filtration and drainage. Water drives many failures in North Carolina. Nonwoven geotextiles line underdrain and edge-drain trenches, wrap perforated pipe, and separate drainage stone from surrounding soils behind retaining walls and backwalls. Matching pore size and permittivity to local soils lets water move while fines stay put, reducing clogged outlets, wet spots, and shoulder drop-offs. In colder foothill and mountain zones, a nonwoven over open-graded aggregate also forms a capillary break, limiting upward moisture that fuels frost heave and weakens base layers.

Riprap underlayment and scour control. Where flows concentrate—culverts, storm outfalls, channel bends, and coastal works—geotextiles serve as underlayment beneath riprap or armor stone. A robust nonwoven filter is placed on the prepared bed or slope before rock. It prevents subgrade from piping through voids during high velocities, hurricane surge, and drawdown, helping the rock “lock in” and protecting embankments at bridge approaches, inlet revetments, and estuarine shorelines.

Structures and MSE walls. NCDOT corridors include many mechanically stabilized earth (MSE) walls and grade separations. Geotextiles act as joint and face filters behind precast panels or modular block, keeping backfill fines from migrating to the face while maintaining drainage continuity. The same concept applies at wingwalls, backwalls, and around penetrations, where a filter layer preserves weeps without trapping water.

Pavement interlayers. Asphalt-impregnated nonwoven geotextile beneath overlays improves waterproofing and slows reflective cracking—important where wide temperature swings, heavy axle loads, and coastal salt spray accelerate pavement aging. On chip seals common to secondary routes, paving fabrics limit water intrusion into base and subgrade, extending service life with minimal added thickness.

Temporary erosion and sediment control. Geotextiles appear in silt fence, inlet protection, curb socks, and check structures. They filter runoff while trapping fines—critical for stormwater compliance on steep cuts in the mountains, long medians in the Piedmont, and urban work zones on the coast. At project entrances, stabilized construction exits typically include a nonwoven geotextile beneath coarse rock to spread wheel loads and keep stone from punching into wet soils, reducing track-out.

Liner protection and containment. Heavy nonwoven geotextiles cushion geomembranes in stormwater basins, lined ditches, salt-shed pads, and deicing-brine containment, protecting liners from puncture by angular aggregate and construction traffic.

Field practice. Performance hinges on basics: prepare subgrades smooth, avoid wrinkles, overlap or sew seams as required, anchor with pins or the first lift, and cover promptly to limit UV and heat exposure. Selection is function-driven—woven for stabilization and tensile capacity; nonwoven for filtration, drainage, and protection—tuned to North Carolina’s soils, hydraulics, and traffic demands.

North Carolina NCDOT