UFC 3-270-04
15 March 2001
adjacent slab (Figure 5.8.). When placing a partial-depth patch along a shoulder joint, place a
piece of joint material along the slab edge even with the surface to prevent the patch material
from penetrating the shoulder interface. Otherwide, the material may restrict longitudinal
movement of the slab in response to thermal changes and result in damage to the repair or the
shoulder.
5.7. Patch Materials. High early-strength PCC (usually Type III cement) should be used when
early opening to traffic is required. When using this material, an epoxy bonding agent should be
used. The concrete should not be placed until the epoxy becomes tacky.
Normal set Type I PCC can be used when the patch material can be protected from traffic for
24 hours. A light coat of bonding mortar, one part portland cement to one part sand by volume
with sufficient water to produce a mortar with a creamy consistency, is applied to the patch area.
The concrete must be placed before the grout dries. If the grout dries or hardens prior to place-
ment of this concrete, it should be removed by sandblasting. Patches using normal-set concrete
should not be placed when the air temperature is below 50 degrees Fahrenheit (10 degrees
Celsius). At temperatures below 55 degrees Fahrenheit (13 degrees Celsius), a longer curing
period and/or insulation mats may be required. Rapid-set proprietary patching materials should
be used in compliance with the manufacturer's recommendations. This includes bonding,
placing, time required before opening to traffic, and temperature ranges. Epoxy mortar and
epoxy concrete mix designs should be evaluated in the laboratory before use. The epoxy resin
catalyst should be preconditioned before blending to produce a liquid blended between 75 and
90 degrees Fahrenheit (24 and 32 degrees Celsius). The epoxy components should be mixed in
compliance with the manufacturer's recommendations prior to addition of aggregate. The
material should be blended in a suitable mixer until homogenous. Only the quantity of material
that can be used within 1 hour (dependent on materials and air temperature, may be less than
1 hour) should be mixed in each batch.
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