Geotextile DOT Information

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.

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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.