MnDOT specifications for geotextile under riprap.
Link to this table

Geotextile Properties for Use Under Riprap
Geotextile Property
Test Method (ASTM) and Units
Type 3 (under Class I and Class II random riprap) (a)
Type 4 (under Class III and Class IV random riprap and hand-placed riprap, slopes up to 3:1) (a)
Type 7 (under Class III and Class IV random riprap, slopes > 3:1) (a)(b)
B1 Grab Tensile Strength minimum, each principal direction
D4632 lb
100
200
300
B2 Elongation minimum, each principal direction
D4632 percent
50
50
50
B3 Seam Breaking Strength minimum (c)
D4632 lb
90
180
270
B4 Apparent Opening Size (AOS) maximum (d)
D4751 U.S. Std. sieve size
50
50
50
B5 Permittivity minimum (e)
D4491 falling head sec−1
0.5
0.5
0.5
B6 Puncture strength minimum
D6241 lb
-
-
-
B7 Wide Width Strip Tensile Strength minimum each principal direction
D4595 lb/ft
-
-
-

(a) Minimum Average Roll Values (MARV) based on average of at least three tests per swatch. (b) Needle-punched nonwoven. Do not use thermally bonded (heat-set) fabric. (c) Adhere to this requirement if the contract requires or allows seams. Strength specifications apply to factory and field seams. Use thread for sewing that has strength of at least 25 lb . Sew seams with a Federal Type 401 stitch using a two-spool sewing machine, and install seams facing upward. For seaming with adhesives, see the Approved/Qualified Products List available at the Department’s website. (d) For U.S. sieve sizes, the AOS Number must be equal to or greater than the number specified. (e) Permittivity: P = K/L, where K = fabric permeability and L = fabric thickness.

This page was last edited on 13 April 2020, at 19:33.

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