Specifications for Transportation Materials and
Methods of Sampling and Testing, Part I -
Specifications, Copyright 1999 by the American
Association of State Highway and Transportation
Officials (AASHTO), Washington, D.C. AASHTO has
given permission to use this information.
Values for grab strength, seam strength, tear
strength, and puncture strength for various
applications can be obtained from the AASHTO M 288 -
Standard Specification for Geotextiles. The most
recent version of M 288 should be used as a
reference. The table in M 288 is divided into three
geotextile classes. The severity of installation
conditions for the application generally dictates
the required geotextile class.
The following values for permittivity and apparent
opening size (AOS) are from AASHTO M 288. Values
for permittivity and maximum AOS should be compared
to actual values of commonly manufactured products
to assure there are a sufficient number of
manufacturers who can meet specifications.
AASHTO M288 PERMITIVITY AND AOS REQUIREMENTS
------------------------------------------------------
SOIL TO BE
MINIMUM
MAXIMUM
FILTERED
PERMITIVITY
AOS
------------------------------------------------------
TEST METHOD
ASTM D 4491
ASTM D 4751
------------------------------------------------------
UNITS
(1/SECONDS)
(MM)
------------------------------------------------------
LESS THAN 15 PERCENT
0.5
0.43
PASSING NO. 200
(NO. 40 SIEVE)
------------------------------------------------------
15 TO 50 PERCENT
0.2
0.25
PASSING NO. 200
(NO. 60 SIEVE)
------------------------------------------------------
GREATER THAN 15 PERCENT
0.1
0.22
PASSING NO. 200
(NO. 70 SIEVE)
------------------------------------------------------
The values listed above provide general guidance
only. A site specific geotextile design should be
performed especially if one or more of the following
problematic soil environments are encountered:
unstable or highly erodible soils such as
non-cohesive silts; gap graded soils; alternating
sand/silt laminated soils; dispersive clays; or rock
flour. For cohesive soils with a plasticity index
greater than 7, the geotextile maximum average roll
value for AOS should be 0.30 mm (No. 50 sieve).
Compatibility testing should be considered in
situations where the geotextile will be exposed to
chemicals which could degrade its physical
properties. Refer to ASTM D 5322 - Practice for
Immersion Procedures for Evaluating the Chemical
SECTION 02373
Page 7
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