Indiana INDOT Geotextile Fabrics

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

Indiana INDOT  - Geotextile Uses

Indiana projects span glacial tills on the northern lake plains, outwash sands along river corridors, silty loams in central counties, and karstic limestone in the south. Add freeze–thaw cycles, lake-effect snow and deicing salts, spring rains, and heavy truck volumes on key freight routes, and you get subgrades that can soften, pump, rut, and lose fines. Geotextile is the quiet engineering layer that helps pavements, structures, and drainage systems keep performing.

The first role is separation and stabilization. On new lanes, shoulder widenings, full-depth reclamation, and staged construction over marginal subgrade, a woven geotextile is placed between native soil and imported base. It prevents fine soils—especially silty tills—from migrating up into the aggregate under traffic, spreads load, and preserves base thickness. Where subgrades are very soft or wet (utility crossings, low shoulders, reclaimed areas), crews roll out geotextile to create a working platform so trucks and pavers don’t punch through. On exceptionally weak ground, the fabric is often paired with a geogrid for added stiffness.

Because water drives many failures, filtration and drainage are constant priorities. Nonwoven geotextiles line underdrain trenches, wrap perforated pipes, and separate drainage stone from surrounding soils behind retaining walls and abutments. Matching apparent opening size and permittivity to local soils—tight tills versus cleaner outwash sands—lets water move while fines stay put, reducing clogged outlets, wet spots, and shoulder drop-offs. In cold regions, pairing a nonwoven with open-graded aggregate also forms a capillary break, limiting upward moisture that fuels frost heave and base softening.

Where flows concentrate—culverts, storm outfalls, streambanks, and channel linings—geotextiles serve as riprap underlayment. A robust nonwoven filter is placed on the prepared slope before armor rock. It prevents underlying soils from piping through voids during high velocities and debris-laden floods, helping the riprap lock in and protecting embankments at bridge approaches and channel bends along rivers like the Wabash and White. In areas with fluctuating groundwater or backwater conditions, generous overlaps or sewn seams keep the filter continuous under shifting hydraulics.INDOT corridors include extensive mechanically stabilized earth (MSE) walls and grade separations. Here, geotextiles act as joint and face filters, tucked behind panel or block joints so backfill fines don’t migrate to the face while drainage continuity is preserved. The same concept applies around structural penetrations and backwalls, where a filter layer protects weeps and outlets from silty inflow.

Indiana also makes effective use of pavement interlayers. Asphalt-impregnated nonwoven geotextile beneath overlays improves waterproofing and slows reflective cracking—important where large daily temperature swings and deicing practices accelerate pavement aging. On chip seals, paving fabrics help limit water intrusion into base and subgrade, extending service life on rural routes and high-volume arterials alike.

For temporary erosion and sediment control, geotextiles appear in silt fence, inlet protection, curb socks, and check dams. They filter flow while trapping fines—crucial for stormwater compliance on steep cuts, long medians, and urban work zones. At project entrances, stabilized construction exits typically include a nonwoven geotextile beneath coarse rock; the fabric spreads wheel loads and prevents the stone from punching into wet soils, reducing track-out.

Finally, geotextiles provide liner protection in stormwater basins, lined ditches, salt-shed pads, and containment areas. Heavy nonwoven fabrics cushion geomembranes from angular aggregate and construction traffic, reducing puncture risk.

Good field practice ties it together: prepare subgrades smooth, avoid wrinkles, overlap or sew seams as needed, anchor with pins or the first lift, and cover promptly. Selection is function-driven—woven for stabilization and tensile capacity; nonwoven for filtration, drainage, and protection—tuned to Indiana’s soils, hydraulics, and traffic demands.

Indiana INDOT