Delaware DELDOT Geotextile Fabrics

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

Delaware DELDOT - Geotextile Uses

Delaware’s network crosses tidal marshes, flat coastal plains, river valleys, and urban corridors. High water tables, silty clays, beach sands, nor’easters, and occasional tropical remnants all stress pavement and drainage systems. Geotextiles are the quiet engineering layer that helps projects resist pumping, rutting, erosion, and the movement of fines.

The first job is separation and stabilization. On new lanes, shoulder widenings, and full-depth reclamation, a woven geotextile is placed between native soils and imported base. It keeps fine soils from migrating up into the aggregate under traffic, spreads load, and preserves base thickness—especially valuable on soft marsh fills and along low shoulders that stay wet. On very weak ground, the fabric also serves as an initial working platform so trucks and pavers don’t punch through during construction.

Next is filtration and drainage. Nonwoven geotextiles line underdrain trenches, wrap perforated pipes, and separate drainage stone from surrounding soils behind retaining walls and abutments. Matching apparent opening size (AOS) and permittivity to local soils—tight silts inland, cleaner sands near the coast—lets water pass freely while fines stay put. That balance reduces clogged outlets, shoulder depressions, and wet spots that shorten pavement life.

Where flows concentrate—culverts, storm outfalls, tidal creeks, and riverbanks—geotextiles act as riprap underlayment. A robust nonwoven filter is placed on the prepared slope before armor rock. It prevents underlying soil from piping through rock voids during high velocities, tidal cycles, or debris-laden storms, helping the rock “lock in” and protecting embankments at bridge approaches and channel bends. Along outfalls in flat terrain, the fabric helps maintain scour protection even when backwater or tides reverse flow direction.

DelDOT projects also rely on geotextiles for temporary erosion and sediment control. Silt fence uses a woven filtration fabric to intercept sheet flow on disturbed ground, allowing sediment to settle while water seeps through. Inlet protection and check structures often include geotextile as the filtering layer so fines are captured without damming water. At project entrances, stabilized construction exits typically include a nonwoven geotextile under coarse rock; the fabric distributes wheel loads and prevents the stone from punching into saturated soils, limiting track-out onto public roads.

In structures and earth-retaining systems, geotextiles serve as joint and face filters. Mechanically stabilized earth (MSE) walls—precast panel or modular block—use strips of geotextile behind vertical and horizontal joints so backfill fines don’t migrate to the face. The same concept applies around structural penetrations and backwalls, preserving weeps and outlets while keeping the fascia clean.

Delaware also makes effective use of pavement interlayers. Asphalt-impregnated nonwoven geotextile beneath overlays improves waterproofing and slows reflective cracking—useful where deicing salts, heavy commuter traffic, and frequent wetting accelerate pavement aging. In chip seals, paving fabrics can extend service life by limiting water intrusion.

Finally, geotextiles provide liner protection in detention basins, lined ditches, and salt-shed pads. Heavy nonwoven fabrics cushion geomembranes from angular aggregate and equipment, reducing puncture risk.

Field practice ties it all together: prepare subgrades smooth, avoid wrinkles, overlap seams generously (or sew where required), anchor with pins or initial lifts, and cover promptly to limit UV exposure and tidal wear. Selection is function-driven—woven for stabilization and tensile strength; nonwoven for filtration, drainage, and protection—tuned to the project’s soils, hydraulics, and traffic demands.

Bottom line: on DelDOT work, geotextile isn’t “landscape fabric.” It’s a purpose-chosen engineering layer that stabilizes soft ground, controls water and fines, protects structures and channels, and stretches pavement life across Delaware’s coastal and riverine conditions.

Delaware DELDOT