Wisconsin WISDOT Geotextile Fabrics

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

Wisconsin WISDOT - Geotextile Uses

Wisconsin projects span dense glacial tills, lakebed clays along Lake Michigan and Superior, sandy outwash in central counties, peat and organics in wetlands, and urban fills. Add long freeze–thaw seasons, deep frost, spring snowmelt, heavy rains, and deicing brines, 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 through those stresses.

Separation and stabilization. On new lanes, shoulder widenings, and rehabilitation work, a woven geotextile is placed between native soil and granular base. The fabric keeps fine soils—especially silts and clays—from migrating into the aggregate under traffic, spreads wheel loads, and preserves base thickness. Where subgrades are very soft or saturated—wetland approaches, low shoulders, utility cuts—crews often roll out geotextile first to create a working platform so haul trucks and pavers don’t punch through. On exceptionally weak ground, geotextile is paired with a geogrid to raise stiffness and speed construction.

Filtration and drainage. Water drives many failures in Wisconsin. Nonwoven geotextiles line underdrain and edge-drain trenches, wrap perforated pipe, and separate drainage stone from surrounding soils behind retaining walls and abutments. Selecting the right apparent opening size (AOS) and permittivity lets water move while fines stay put, cutting off the mechanisms that clog outlets, create wet spots, and destabilize shoulders. In freeze–thaw zones, a nonwoven placed over open-graded aggregate also forms a capillary break, limiting upward moisture that fuels frost heave and weakens base layers in winter.

Riprap underlayment and scour control. Where flows concentrate—culverts, storm outfalls, river bends, and shoreline works—geotextiles serve as underlayment beneath riprap or armor stone. A robust nonwoven filter goes on the prepared bed or slope before rock placement. It prevents subgrade soils from piping through rock voids during high velocities, seiche effects on the Great Lakes, rapid drawdown, and debris-laden floods, helping the armor “lock in” and protecting embankments at bridge approaches and channel transitions on the Wisconsin, Mississippi, Fox, and Menominee systems.

Structures and MSE walls. WisDOT corridors include extensive mechanically stabilized earth (MSE) walls and grade separations. Geotextiles act as joint and face filters, tucked behind panel or modular block joints so backfill fines don’t migrate to the face while drainage continuity is preserved. The same concept applies at wingwalls, backwalls, and around penetrations, where a filter layer keeps weeps functioning without trapping water and prevents staining at the fascia.

Pavement interlayers. Asphalt-impregnated nonwoven geotextile beneath overlays improves waterproofing and slows reflective cracking—important where thermal cycling, heavy axle loads, and deicing chemicals accelerate pavement aging. On chip seals common to preservation programs, paving fabrics limit water intrusion into base and subgrade, extending service life with minimal added thickness.

Temporary erosion and sediment control. During construction, 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, long medians, and urban work zones. At site entrances, stabilized construction exits typically include a nonwoven geotextile beneath coarse stone; the fabric distributes wheel loads and prevents rock from punching into wet soils, reducing track-out onto public roads.

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

Field practice that makes it work. Prepare subgrades smooth, remove protrusions, avoid wrinkles; orient rolls correctly; lap or sew seams as specified (larger overlaps on very soft ground); anchor with pins or the first lift; and cover promptly to limit UV and weathering. Selection stays function-driven—woven for stabilization and tensile capacity; nonwoven for filtration, drainage, and protection—tuned to Wisconsin’s soils, hydraulics, and traffic demands.

Bottom line: on WisDOT projects, geotextile isn’t “landscape fabric.” It’s a purpose-chosen engineering layer that stabilizes variable subgrades, controls water and fines through harsh seasons, protects structures and channels, and stretches pavement life statewide.

Wisconsin WISDOT