FRP Systems
FRP
system forms can be categorized based on how they are delivered
to the site and installed. External FRP reinforcing systems come
in a variety of forms including 1) wet lay-up systems, 2)
precured systems and 3) Near Surface Mounted Systems (NSM).
Overview of Wet Lay-up Systems
Wet lay-up FRP systems
consist of dry unidirectional or multidirectional fiber sheets or fabrics
that are impregnated on-site with a saturating resin. The saturating resin
is used to provide a binding matrix for the fiber and bond the sheets to
the concrete surface. Wet lay-up systems are saturated with resin and
cured in place and in this sense are analogous to cast-in-place concrete.
Three common types of wet lay-up systems are listed below:
Products
-
Dry unidirectional
fiber sheets with the fiber running predominantly in one planar (0 axis)
direction
-
Dry
multidirectional fiber sheets or fabrics with fibers oriented in at
least two planar directions
-
Dry fiber tows
that are wound or otherwise mechanically applied to the concrete
surface. The dry fiber tows are impregnated with resin during the
winding operation.
Installation/Application
-
Prepare Substrate
– The
concrete, masonry or steel surface must be properly prepared prior to
bonding. There shall be no spalling or delamination in the case of
concrete and the corners must be ground to a minimum radius of 10mm (3/8
in.). The bearing substrate surface is typical roughened by grinding or
sandblasting. Sandblasting is normally used on steel. Any unevenness in
the concrete or masonry is removed with a mineral-based re-profiling
mortar.
-
Prime Concrete
Surface –
Some systems require that the dust-free surface be coated with a
primer. For steel a sandblasted surface yields the best results.
-
Apply Epoxy –
To saturate the sheet and simplify installation, the adhesive/matrix
resin is applied to the front and back of the material. Mix and apply
epoxy onto surface using a roller or brush. Once the material has been
wet-out with the liquid resin, the material may be rolled for ease of
transport and/or application to the place of application.
-
Place FRP Sheet on
Structure –
Unroll sheet rolls
onto the structural element being strengthened. Tension is maintained to
minimize intrusion of air entrainment behind sheet. Placing one layer at
a time, apply pressure to wrap using a roller. A hard rubber roller with
ridges (air relief roller) works well for this application.
-
Apply Epoxy to
Sheet Surface –
A topcoat of epoxy can now be applied to the sheet to fully saturate the
material. If applicable, quartz sand can be applied to topcoat prior to
curing to provide a textured surface for plaster or painting.
Go to last
section: Features & Benefits and Codes & Specs
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FRP Systems: Precured
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