Road Construction

Geotextile DOT Information

road construction, geotextile, highway The use of geotextiles in road construction is no mystery. The geotextiles act as separators, filters, and stabilizers. The following tables display standard specifications for woven and non-woven geotextiles used for highway applications. The specifications are based on geotextile survivability from installation stresses.



Geotextile Strength Property Requirements

  Test Methods Class 1 Elongation <50% Class 1 Elongation ≥50% Class 2 Elongation <50% Class 2 Elongation ≥50% Class 3 Elongation <50% Class 3 Elongation ≥50%
Grab Strength ASTM D4632 1400 900 1100 700 800 500
Sewn Seam Strength ASTM D4632 1260 810 990 630 720 450
Tear Strength ASTM D4533 500 350 400 250 300 180
Puncture Strength ASTM D4833 500 350 400 250 300 180

Subsurface Drainage Requirements

Geotextile Class 2 Test Methods Units % In Situ Soil Passing 0.075 mm <15 % In Situ Soil Passing 0.075 mm 15-50 % In Situ Soil Passing 0.075 mm >50
Permittivity ASTM D4491 sec -1 0.5 0.2 0.1
Apparent Opening Size ASTM D4751 mm 0.43 0.25 0.22
Ultraviolet Strength
(Retained Strength)
ASTM D4355 % 50% after 500 hours of Exposure 50% after 500 hours of Exposure 50% after 500 hours of Exposure

Description: This specification is applicable to placing a geotextile against a soil to allow for long-term passage of water into a subsurface drain system retaining the in situ soil for road construction.

Note: Woven Slit Film Geotextiles are not allowed.

Questions? We can help! Call the GEI Works team at +1-772-646-0597 or submit a form.

Separation Requirements

Geotextile Class 2 Test Methods Units Requirements
Permittivity ASTM D4491 sec -1 0.02
Apparent Opening Size ASTM D4751 mm 0.60
Ultraviolet Strength
(Retained Strength)
ASTM D4355 % 50% after 500 hours of Exposure

Description: This specification is applicable to the use of a geotextile to prevent the mixing of a subgrade soil and an aggregate cover material. The separation application is appropriate for pavement structures constructed over soils with a California Bearing Ratio equal to or greater than 3 and unsaturated subgrade soils.

Stabilization Requirements

Geotextile Class 1 Test Methods Units Requirements
Permittivity ASTM D4491 sec -1 0.05
Apparent Opening Size ASTM D4751 mm 0.43
Ultraviolet Strength
(Retained Strength)
ASTM D4355 % 50% after 500 hours of Exposure

Description: This specification is applicable to the use of a geotextile in wet, saturated conditions to provide the coincident functions of separations and filtration. In some installations, the geotextile can also provide the function of reinforcement. Stabilization for road construction is applicable to pavement structures constructed over soils with a California Bearing Ratio between one and three.

The stabilization application is appropriate for subgrade soil that are saturated due to a high groundwater table of due to prolonged periods of wet weather.

Note:This specification is not appropriate for embankment reinforcement where stress conditions may cause global subgrade foundation or stability failure during road construction.

Questions? We can help! Call the GEI Works team at +1-772-646-0597 or submit a form.

Permanent Erosion Control Requirements

Geotextile Class 1 & 2 Test Methods Units % In Situ Soil Passing 0.075 mm <15 % In Situ Soil Passing 0.075 mm 15-50 % In Situ Soil Passing 0.075 mm >50
Permittivity ASTM D4491 sec -1 >0.7 0.2 0.1
Apparent Opening Size ASTM D4751 mm 0.43 0.25 0.22
Ultraviolet Strength
(Retained Strength)
ASTM D4355 % 50% after 500 hours of Exposure 50% after 500 hours of Exposure 50% after 500 hours of Exposure

Description: This specification is applicable to the use of a geotextile between energy absorbing armor systems and in the in situ soil to prevent soil loss resulting in excessive scour and to prevent hydraulic uplift pressures causing instability of the permanent erosion control system.

Note: This specification does not apply to other types of geosynthetic soil erosion control materials such as turf reinforcement mats and Woven Slit Film Geotextiles are not allowed.

Temporary Silt Fence Requirements

  Test Methods Units Supported Silt Fence Unsupported Silt Fence Elongation ≥50% Unsupported Silt Fence Elongation <50%
Maximum Post Spacing     1.2 m 1.2 m 2 m
Grab Strength ASTM D4632 N      
Machine Direction     400 550 550
X-Machine Direction     400 450 450
Permittivity ASTM D4491 sec-1 0.05 0.05 0.05
Apparent Opening Size ASTM D4751 mm 0.60 0.60 0.60
Ultraviolet Stability
(Retained Strength)
ASTM D4355 % 70% after 500 hrs of exposure 70% after 500 hrs of exposure 70% after 500 hrs of exposure

Description: This specification is applicable to the use of a geotextile as a vertical, permeable, interceptor designed to remove suspended soil from overland water flow.

Note: The geotextile used for temporary silt fence may or may not be supported between posts with wire or polymeric mesh. The minimum height is 750 mm. Minimum embedment depth is 150 mm.

Paving Fabric Requirements

  Test Methods Units Requirements
Grab Strength ASTM D4632 N 450
Ultimate Elongation ASTM D4632 % ≥50
Mass per Unit Area ASTM D5261 gm/m² 140
Asphalt Retention ASTM D6140 l/m² See Notes Below
Melting Point ASTM D276 °C 150

Description: This specification is applicable to the use of a paving fabric, saturated with asphalt cement, between pavement layers. The function of the paving fabric is to act as a waterproofing and stress relieving membrane within the pavement structure.

Note: Asphalt required to saturate paving fabric only. Asphalt retention must be provided in manufacturer certification. Product asphalt retention property must meet the MARV value provided by the manufacturer certification.

Read about how Water Trailers can be used in road construction.

Questions? We can help! Call the GEI Works team at +1-772-646-0597 or submit a form.