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Division 41 — Construction Materials

4196Engineering Fabrics

IA · 2023 Standard SpecificationsBook pages 12711288View official source ↗

4196.01 A.

B.

GENERAL REQUIREMENTS. 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.

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

b.The fabric may be reinforced with plastic netting or wire. Fabric

property requirements shall remain as listed in Table 4196.01-1. Table 4196.01-1: Silt Fencing Fabric Properties Property Value Test Method No.

Grab Strength, dry, minimum average fill direction run direction

100 lbs. 150 lbs.

ASTM D 4632

Ultraviolet Stability (Retained Strength)

70%

ASTM D 4355

Permittivity

0.05

ASTM D 4491

US Sieve No. 30

ASTM D 4751

Apparent Opening Size, maximum

Engineering Fabrics

2.

4196.01

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 ASTM D 4632 average value in either principal 90 lbs. direction Elongation, dry, minimum average value in either principal 20% ASTM D 4632 direction Permittivity, minimum 0.1 sec-1 ASTM D 4491 Apparent Opening Size, US Sieve No. 40 ASTM D 4751 maximum

3.

Embankment Erosion Control. Under concrete and stone revetment, erosion stone, or gabions used for embankment 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 as Embankment Erosion Control Property Value Test Method Grab strength, dry, minimum average value in either principal 150 lbs. ASTM D 4632 direction Elongation, dry, minimum average value in either principal 20% ASTM D 4632 direction Permittivity, minimum 0.1 sec-1 ASTM D 4491 Apparent Opening Size, US Sieve No. 40 ASTM D 4751 maximum

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.

ASTM D 4632

Elongation, dry, minimum average value in either principal direction

20%

ASTM D 4632

4196.01

Engineering Fabrics

Grab Strength after 400°F for 3 hr.(a) minimum average value in either principal 75 lbs. ASTM D 4632 direction

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

b.

c.

5.

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 of asphalt binder per square yard is used. The Engineer may approve fabrics, such as fiberglass, which do not lend themselves to testing by some of the previously specified methods.

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 4196.01-5a or 4196.01-5b. Table 4196.01-5a: Fabric for use as Subgrade Stabilization (Biaxial Polymer Grid) Property Value Test Method

Minimum tensile strength at 2% strain. Both directions.

250 lbs./ft.

ASTM D 6637

Aperture size. Both directions.

0.5 to 2 in.

Internal Dimension Measuring Calipers

Minimum Ultimate junction strength. Both directions.

790 lbs./ft.

GRI Test Method GG2 or ASTM D 7737

Table 4196.01-5b: Fabric for use as Subgrade Stabilization (Triaxial Polymer Grid) Property Value Test Method Minimum radial stiffness at 0.5% strain 13,700 lbs./ft. or ASTM D 6637 or 12,000 lbs./ft. Minimum tensile modulus at 2% strain Minimum isotropic stiffness ratio

0.60

ASTM D 6637 (a)

Aperture size.

0.5 to 2 in.

Internal Dimension Measuring Calipers

Minimum junction efficiency

90%

ASTM D 6637/D 7737

(a)Ratio between minimum and maximum values of radial stiffness at 0.5%

strain, measured on rib and midway between rib directions.

b.

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

Engineering Fabrics

6.

4196.01

Bridge Abutment Backfill Fabric. Use engineering fabric having properties listed in Table 4196.01-6.

Table 4196.01-6: Fabric for use in bridge abutment backfill Property Value Test Method Tensile Strength (at 5% Strain), 1356 lbs/ft ASTM D 4595 minimum Apparent opening size (AOS), US Sieve No. 40 ASTM D 4751 maximum UV resistance (at 500 hours)

70% retained strength

ASTM D 4355

Flow Rate, minimum

10 gal./min./ft2

ASTM D 4491

Source: Iowa Standard Specifications for Highway and Bridge Construction, 2023 Edition. Pages 12711288 of 1,288.

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Iowa DOT Standard Specifications for Highway and Bridge Construction Section 4196 Engineering Fabrics — Full Text | BuildSpec