Section 4196. Engineering Fabrics

4196.01 general requirements.

 

A. Meet the following requirements for engineering fabrics (known as geotextiles):

 

1. Permeable, synthetic textile materials suitable for use with soil, rock, or other geotechnical engineering related materials as an integral part of a highway project, structure, or system.

 

2. Mildew, rot, insect, and rodent resistant.

 

3. Inert to commonly encountered chemicals found in soil.

 

4. During all periods of shipment and storage, the fabric is maintained by wrapping in a heavy duty protective covering to protect the fabric from direct sunlight, ultraviolet rays, mud, dirt, dust, and debris.

 

5. Free of defects or flaws which significantly affect its physical properties.

 

B. Comply with Materials I.M. 496.01 for inspection and acceptance of engineering fabrics. Label each roll of fabric in a shipment with a number or symbol to identify the production run. Meet the following additional fabric requirements for the specific applications:

 

1. Silt Fencing.

a. Meet the following requirements:

1) Woven material with a minimum width of 36 inches (0.9 m).

2) Top edge of the fabric hemmed or modified otherwise so that a braided cord or woven belt can be suitably attached for loop tying to fence posts.

3) The cord or belt of minimum tensile strength of 150 pounds (670 N).

4) Fabric and any reinforcing plastic netting contains or is treated with ultraviolet stabilizers, sufficient to prevent damaging deterioration for 2 years of outdoor exposure.

5) Has the properties listed in Table 4196.01-1.

b. The fabric may be reinforced with plastic netting of nominal 3/4 inch (19 mm) strand spacing and a minimum three strand grab strength of 40 pounds (180 N) and 15 pounds (70 N) after the same accelerated weathering as required for the fabric. Fabric that is reinforced in this manner may have lower grab strengths as indicated.

 

Table 4196.01-1: Silt Fencing Fabric Properties

Property

Value

Test Method No.

Grab Strength, dry, minimum average

fill direction

run direction(a)

 

100 lbs. (445 N)

150 lbs. (667 N)

ASTM D 4632

Ultraviolet Stability (Retained Strength)

70%

ASTM D 4355

Permittivity

0.05

ASTM D 4491

Apparent Opening Size, maximum

US mesh 30

(600 m)

ASTM D 4751

(a) When plastic net reinforcing is used, ensure the minimum average grab strength requirement for fabric, before and after accelerated weathering, is 100 pounds (445 N) and 35 pounds (155 N), respectively. Apply the grab strength to both the fill and run direction.

 

2. Subsurface Drainage.

In subsurface drains, use fabric that:

         Is capable of withstanding normal installation stresses, and

         Has the properties listed in Table 4196.01-2.

 

Table 4196.01-2: Fabric for use in Subsurface Drains

Property

Value

Test Method

Grab strength, dry, minimum average value in either principal direction

 

90 lbs. (400 N)

ASTM D 4632

Elongation, dry, minimum average value in either principal direction

20%

ASTM D 4632

Permittivity

0.02 - 0.30

ASTM D 4491

Apparent Opening Size, maximum

US mesh 40 (450 m)

ASTM D 4751

 

3. Embankment Erosion Control.

Under erosion stone or gabions used for embankment or erosion control, use fabric that:

         Is capable of withstanding normal installation stresses, and

         Has the properties listed in Table 4196.01-3.

 

Table 4196.01-3: Fabric for use under Erosion Stone

Property

Value

Test Method

Grab strength, dry, minimum average value in either principal direction

150 lbs. (667 N)

ASTM D 4632

Elongation, dry, minimum average value in either principal direction

20%

ASTM D 4632

Permittivity

0.02 - 0.30

ASTM D 4491

Apparent Opening Size, maximum

US mesh 40 (450 m)

ASTM D 4751

 

4. Asphalt Overlay Fabric.

a. When placing fabric under asphalt mixtures to provide waterproofing and delay reflective cracking, ensure the fabric:

         Is capable of withstanding installation stresses,

         Is not damaged by temperatures common to asphalt mixtures, and

         Has the properties listed in Table 4196.01-4.

 

Table 4196.01-4: Fabric Placed under Asphalt Mixtures

Property

Value

Test Method

Grab strength, dry, minimum average

value in either principal direction

 

90 lbs. (400 N)

 

ASTM D 4632

Elongation, dry, minimum average value

in either principal direction

 

20%

 

ASTM D 4632

Grab Strength after 400F (204C) for 3 hr.(a) minimum average value in either principal direction

 

75 lbs. (335 N)

 

ASTM D 4632

(a) Applies only when asphalt temperatures exceeding 300F (149C) are anticipated.

 

b. Ensure asphalt absorption is sufficient to produce a good bond between the overlay and the overlaid surface when a tack coat of 0.20 gallon to 0.25 gallon (0.9 L to 1.1 L) of asphalt binder per square yard (square meter) is used.

c. The Engineer may approve fabrics, such as fiberglass, which do not lend themselves to testing by some of the previously specified methods.

 

5. Subgrade Stabilization Material.

a. To stabilize a subgrade under pavement or pavement patches, use material that:

         Is capable of withstanding installation stresses, and

         Has the properties listed in Table 4196.01-5 for the type specified for use in the contract documents.

 

Table 4196.01-5: Fabric for use as Subgrade Stabilization

(Polymer Grid)

Property

Value

Test Method

Minimum tensile strength at 2% strain.

Both directions.

250 lbs./ft. (3650 N/m)

GRI Test Method GG1-87

Maximum aperture.

Both directions.

2 in. (50 mm)

Internal Dimension Measuring Calipers

Minimum aperture.

Both directions.

0.5 in. (13 mm)

Internal Dimension Measuring Calipers

Minimum Ultimate junction strength.

Both directions.

800 lbs./ft. (11,675 N/m)

GRI Test Method GG2-87

 

b. Inspection and acceptance of polymer grid will be according to Materials I.M. 496.01.

 

6. Concrete and Stone Revetment and Bridge Abutment Backfill Fabric.

Use engineering fabric having properties listed in Table 4196.01-6.

 

 Table 4196.01-6: Fabric for use under conc./stone revetment & abutment backfill

Property

Value

Test Method

Tensile Strength

(at 5% Strain)

1356 lbs/ft

(19.8 kN/m)

ASTM D 4595

Apparent opening size (AOS)

US Sieve #40 (0.43 mm)

ASTM D 4751

UV resistance (at 500 hours)

70% retained strength

ASTM D 4355

Flow Rate

18 gal./min./ft2

(733 L/min./m2)

ASTM D 4491