Pennsylvania PennDOT Geotextile Fabrics

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

Pennsylvania PennDOT - Geotextile Uses

Pennsylvania’s network crosses glacial tills in the northeast and northwest, red shale-derived clays and karstic limestones through the Ridge-and-Valley, alluvial floodplains along the Susquehanna and Delaware, and urban fills around Philadelphia and Pittsburgh. Add long freeze–thaw seasons, deicing salts, nor’easters and tropical remnants, steep Appalachian grades, and heavy truck volumes on I-76, I-80, I-81, and I-95, 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.

Separation and stabilization. On new lanes, shoulder widenings, and rehab work, PennDOT commonly places a woven geotextile between native soil and granular base or subbase. The fabric blocks silts and clays from migrating upward into the aggregate under traffic, spreads load, and preserves base thickness—especially valuable over thaw-weakened tills, soft floodplain approaches, and utility cuts. Where subgrades are very weak or wet, crews first roll out geotextile to create a working platform so haul trucks and pavers don’t punch through; on exceptionally weak ground it is often paired with geogrid for added stiffness and construction speed.

Filtration and drainage. Water drives many failures in Pennsylvania. Nonwoven geotextiles line edge-drain and underdrain trenches, wrap perforated pipe, and separate drainage stone from surrounding soils behind retaining walls, abutments, and wingwalls. Matching apparent opening size (AOS) and permittivity to local soils—tight clays in valleys, cleaner sands along river terraces—lets water move while fines stay put, reducing clogged outlets, wet spots, and shoulder drop-offs. In freeze–thaw zones, a nonwoven placed over open-graded aggregate also creates 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, stream realignments, and riverbanks—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 from piping through rock voids during high velocities, rapid drawdown, ice-out, and debris-laden floods, helping the armor “lock in” and protecting embankments at bridge approaches and channel bends on the Susquehanna, Delaware, Allegheny, Monongahela, and Ohio systems.

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

Pavement interlayers. Asphalt-impregnated nonwoven geotextile beneath overlays improves waterproofing and slows reflective cracking—important where thermal swings, studded tire use in some districts, and deicing chemicals 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, long medians, and urban work zones. At project entrances, stabilized construction exits typically include a nonwoven geotextile beneath coarse rock to spread wheel loads and prevent stone from punching into wet soils, reducing track-out.

Liner protection and containment. Heavy nonwoven geotextiles cushion geomembranes in stormwater basins, lined ditches, salt-storage 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 winter weathering. Selection is function-driven—woven for stabilization and tensile capacity; nonwoven for filtration, drainage, and protection—tuned to Pennsylvania’s soils, hydraulics, and traffic demands.

Pennsylvania PennDOT