9-91 Section 910. Geosynthetics
910.01. General Requirements Geosynthetics must be composed of long chain synthetic fiber of at least 85% (by weight ) polyolefins or polyesters . Geosynthetics must be capable of resisting degradation from chemicals, mildew, rot, and ultraviolet (UV) light. Deliver and store geosynthetics in packaging capable of resisting UV radiation, contaminants, and moisture. Label each unit of material with product information including supplier and lot identification. Do not expose geosynthetics to direct sunlight for prolonged periods . Repair or replace damaged geosynthetics at no additional cost to the Department. 910.02. Testing Geosynthetic testing will be in accordance with the specified ASTM or Departm ent methods, as modified by this section. Geosynthetics must meet the physical property requirements shown in Tables
910-1 and 910- 2. The directional property values listed in Table 910-1 specify
values for the weaker principal direction. 910.03. Geotextiles Geotextiles are flexible, permeable fabrics, consisting of synthetic fibers or yarns oriented into a dimensionally stable network . Woven geotextiles must have sealed or selvaged edges to prevent raveling.
A.Geotextile Blanket . Geotextile for filtration applications, including trench lining, ditch lining, streambed protection, pipe wrap, joint wrap, drainhole and weephole filter, granular blanket separation, and filter bags must be non-woven and meet the requirements shown in Table 910-1 for geotextile blanket.
B.Geotextile Liner . Geotextile for erosion control in riprap and similar applications must be non-woven and meet the requirements shown in Table 910-1 for geotextile liner . Geotextile for use with heavy riprap must be non-woven and meet the requirements shown in Table 910- 1 for heavy geotextile liner.
C.Geotextile Separator . Geotextile used to prevent intermixing of dissimilar aggregate or soil layers must meet the requirements shown in Table
910-1 for geotextile separator . Geotextiles separators with grab tensile
elongation- at-break less than 50% must meet the requirements shown in Table 910-1 for woven geotextile separator . Geotextiles with grab tensile elongation- at-break equal to or greater than 50% must meet the strength requirements shown in Table 910- 1 for non- woven geotextile separator. MDOT Standard Specifications for Construction Section 910
9-92 D. Stabilization Geotextile . Geotextile used to prevent intermixing of soft
subgrade and subbase materials must meet the requirements shown in Table 910-1 for stabil ization geotextile. Stabilization geotextile with grab tensile elongation-at -break less than 50% must meet the requirements shown in Table 910-1 for woven stabilization geotextile. Geotextiles with grab tensile elongation- at-break equal to or greater than 50 % must meet the strength requirements shown in Table 910- 1 for non- woven stabilization geotextile. 910.04. Silt Fence Geotextile Select geotextile for fabricating silt fence from the Qualified Products List . Geotextile f or silt fence must have a nominal height of 3 feet and must meet the requirements shown in Table 910-1 for silt fence. Geotextile for silt fence must have a retained strength of at least 70 % after 500 hours of UV exposure when tested in accordance with ASTM D4355 /D4355M . Fabricate silt fence according to subsection 916.02. 910.05. Drainage Geocomposites Drainage geocomposites must meet the requirements shown in Table 910- 1 and this subsection. Prefabricated geocomposites for drainage applications must consist of a geotextile bonded to or wrapped around a polymer core having corrugated, dimpled, tubular, or net (mesh) configurations . Geocomposites must have sufficient flexibility and durability to withstand installation, handling, and permanent loading stresses. Fittings for geocomposite installations must be manufactured by the geocomposite manufacturer or meet the published specifications of the geocomposite manufacturer . Provide t ape used to seal con nections with adhesive resistant to moisture and organic growth and recommended by the manufacturer for underground service conditions. Obtain the Engineer ’s approval for all components of the geocomposite system before installation.
A.Wall Drain. Wall drains for single-direction cross -planar flow must consist of an impermeable polymer core with geotextile bonded to one side. The geocomposite must have a minimum crush strength of 4, 000 pounds per square foot at no more than 18% deformation when tested according to MTM 411.
B.Geocomposite Net . The Engineer may allow geocomposite net consisting of geotextile blanket bonded to both sides of a m esh core as an alternat ive to open- graded aggregate drainage layers. MDOT Standard Specifications for Construction Section 910
9-93 The Engineer will approve the geocomposite net based on durability,
drainage capacity, crush resistance, tensile strength, and thickness. 910.06. Road Grade Biaxial Geogrid The geogrid must be a regular grid structure and must have aperture geometry and rib and junction cross -section sufficient to permit significant mechanical interlock with the material being reinforced. The geogrid must have significant dimensional stability through all ribs and junctions of the grid structure . The geogrid must maintain its reinforcement and interlock capabilities under repeated dynamic loads while in service . The geogrid must also be resistant to UV degradation, to damage under normal construction practices, an d to all forms of biological or chemical degradation normally encountered in highway construction. The geogrid must be composed of polypropylene, HDPE , or polyester virgin resins . The protective coatings of polyester geogrids must contain less than 5% filler content . Repair damaged coating prior to backfilling. The geogrid must meet the physical property requirements of Table 910- 2. MDOT Standard Specifications for Construction Section 910
9-94 Table 910- 1:
Physical Requirements for Geotextiles Geotextile Category Property Grab Tensile Strength (min .) (lb) Trapezoid Tear Strength (min .) (lb) Puncture Strength (min .) (lb) Permittivity (min .) (per second) Apparent Opening Size (max .) (mm) Test Method ASTM D4632/ D4632M ASTM D4533/ D4533M ASTM D6241 ASTM D4491/ D4491M ASTM D4751 Geotextile blanket(a) 120 45 230 0.5 0.21 Geotextile l iner 200 75 440 0.5 0.21 Heavy geotextile l iner 270 100 620 0.5 0.21 Woven geotextile s eparator 270 100 620 0.05 0.425 Non- woven geotextile s eparator 200 75 440 0.5 0.425 Woven s tabilization geotextile 270 100 620 0.05 0.50 Non- woven s tabilization geotextile 270 100 620 0.5 0.50 Silt fence 100(b) 45 — 0.1 0.60 Drainage geocomposites 200 75 440 0.5 0.21
a.For pipe wrap where backfill around the pipe meets granular material Class II AA requirements; geotextiles, including knitted polyester sock, which meet the following minimum requirements in the applied condition , are permitted : mass/unit area: 3.0 oz/yd²; Mullen burst s trength: 100 psi; maximum apparent opening size must be 0.30 mm for pavement and foundation underdrains and 0.60 mm in other areas . The fluid displacement rate for the Mullen burst test equipment must be 170 mL/min ± 5 mL/min . Subtract tare strength from t he ultimate burst strength as specified in ASTM D3786/D3786M.
b.Elongation at the specified grab tensile strength no greater than 40% for silt fence. MDOT Standard Specifications for Construction Section 910
9-95 Table 910- 2:
Physical Requirements for Road Grade Biaxial Geogrid Property Minimum Value (except where noted below) Test Method Interlock open area 60% U.S. Army Corps of Engineer s(a) Ultimate strength MD(c) MD(c) 1200 lb/ft 1950 lb/ft ASTM D6637 /D6637M(b) Individual junction s trength MD(c) CMD(c) 130 lb 170 lb ASTM D7737/D7737M Tensile modulus (2%) MD(c) CMD(c) 18,000 lb/ft 30,000 lb/ft ASTM D6637 /D6637M(b) Aperture size MD(c) CMD(c) 1.0 inch (nominal v alue) 1.3 in ch (nominal v alue) Measured
a.Percent open area measured without magnification by means of U.S. Army Corps of Engineers method as specified in CW 02215, Civil Works Construction Guide Specification for Plastic Filter Fabric (1977 ).
b.Ultimate strength and t ensile modulus at 2 % elongation measured by means of ASTM D6637 /D6637M. No offset allowances or specimen pretensioning are made in calculating tensile modulus.
c.MD (machine direction) and CMD (cross -machine direction ) refer to the principal directions of the manufacturing process.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 901–905 of 1,146.