UFC 3-270-04
15 March 2001
(PEs), vinyl esters (VEs), and high molecular weight methacrylate (HMWM), a relatively new
material. Curing of the formulations for PC patching materials is generally an exothermic
reaction. The working and curing time for PC is affected by the amount of the promoter and
initiator concentrations, the ambient substrate and component temperatures, thickness, and the
time required to mix, transport, and place the materials. Many factors affect the performance of
these materials so it is essential that the manufacturer's recommendations are carefully followed.
Epoxy compounds are generally formulated in two or more parts. Part A is most often the portion
containing the resin, and Part B is usually the hardener system. Epoxy systems are formulated
for specific uses so the proper epoxy must be selected for the specific job requirements. The
ratio of resin to hardener varies considerably with the formulation of the epoxies. The range of
curing temperatures also varies depending on the specific formulation.
Curing has taken place at temperatures varying from 140 to 5 degrees Fahrenheit (60 to
-15 degrees Celsius) or below. Users of epoxy PC materials should refer to publications issued
by ACI Committee 503 for additional guidance. Aggregates used in PC systems should be of the
highest quality available. The aggregate must usually be dry and always free of dirt, asphalt, and
other organic materials. The required aggregate size distribution is dependent upon the depth of
the patch to be made. The maximum size should not be greater than one-third the depth of the
patch. The distribution should provide for a minimum void volume. This will minimize the voids
and the amount of monomer required to ensure proper bonding of all aggregate particles and will
result in a more economical PC.
11.4. Placement. Methods of placing PC patching include:
11.4.1. Dry pack placement. The graded aggregate is placed in the repair area and compacted
by tamping. The compacted aggregate is then saturated with the monomer mixture by sprinkling
cans or a similar system. Care must be taken to ensure that the aggregate is wetted with
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