Section 13.
UTILIZATION OF REINFORCING FABRICS IN ASPHALT PAVEMENT
1. FUNCTIONS. Reinforcing fabric may be used in asphalt pavement to serve two
functions: a) interlayer between base course and subgrade to not only provide
some reinforcement, but also to prevent intrusion of subgrade fines into
granular base layers and to provide planar flow of water between base and
subgrade, and b) tensile reinforcement of a thin asphalt overlay. Fabrics may
be used to retard or minimize reflection cracking in asphalt resurfacings.
Asphalt and portland cement concrete pavements of all types are frequently
overlayed with additional layers of asphalt concrete to strengthen pavement
that has been weakened due to fatigue cracking or environmentally induced
cracking. Limited experience and test data indicate that fabrics can function
to enhance the service life of asphalt pavement overlays.
2. FABRIC MATERIALS
a. Description. Fabrics available for use in pavement construction are made
of synthetic fibers. The synthetic fiber fabrics are made with uniformity in
production. Some are and some are not resistant to rot and mildew. The pore
sizes in the fabrics are reasonably uniform. Fabric strength and resistance
to chemicals vary from fabric to fabric. Available fabrics are either one of
two types, woven or nonwoven. The woven fabrics are manufactured using the
weaving process whereas the nonwoven fabrics are formed by bonding fibers
together using heat fusion, chemical fusion or needle punching. The types of
fibers used include polyester, polypropylene, polyethylene, polyamides, nylon
or glass.
Representative types and styles of fabrics are summarized in Table 18.
This list was prepared using information provided by fabric manufacturers and
not all data is available for every brand and type of fabric.
b. Fabric Properties. The important fabric properties that affect pavement
performance are described as follows:
(1) Grab Tensile Strength. The tensile strength of the fabric is
important when the fabric serves as a reinforcement. As a pavement system
deforms elastically, the fabric also deforms, thereby inducing tensile
stresses in the fabric. The fabric must have sufficient tensile strength to
resist these stresses.
(2) Trapezoidal Tear Strength. Once a hole or tear has been introduced
into a fabric, the resistance of the fabric to the spreading of the damage is
its tear resistance.
(3) Puncture Resistance. A fabric located between a granular material and
the subgrade is subject to puncture by the granular material during the
placement of the aggregate. The ability of the fabric to resist penetration is
its puncture resistance.
(4) Burst Strength. The ability to resist stresses applied uniformly
over a large area and in all directions is the burst strength of the fabric.
This is a special case of the tensile type of failure.
Change 1, September 1985
36
Previous Page
