MnDOT specifications for geotextile under riprap MnDOT specifications for geotextile under riprap

MnDOT specifications for geotextile under riprap.
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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.