Page 364 - Construction Waterproofing Handbook

8.24 CHAPTER EIGHT

FIGURE 8.20 Mechanical packer for injecting epoxy under high pressures. (Courtesy
of Webac)

The premise of injection work is to allow for maximum epoxy penetration so as to
ensure complete joint sealing. Ports are placed approximately the same distance apart as
crack depth, but not exceeding 6 in. Epoxy is then injected into the lowest port, and injec-
tion is continued until epoxy flows out the next highest port. The lower port is then sealed
off, and injection is continued on the next highest port. After epoxy curing, ports and sur-
face-applied sealers are removed.
Epoxy crack sealing will cause staining of a substrate or possible damage to it during
its removal. In restoration procedures where such damage is not acceptable, such as glazed
terra cotta, hot-applied beeswax may be applied as a sealer in place of epoxy. This wax is
then removed after injection without damage or staining to substrates.
Epoxy injection requires technical knowledge and experience of an installer. Proper
mixing of the two-component materials, proper injection pressures, and knowledge of the
injection process are mandatory for successful installations. (See Table 8.8.)

EPOXY INJECTION APPLICATION

Substrates must be cleaned and completely dry. If both sides of a substrate are accessible,
they should both be sealed and injected to ensure complete crack filling. Cracks accessi-
ble from only one side of a substrate lose a quantity of material out to the unsealed side.
Cracks that are contaminated with dust or dirt cannot be properly injected. All cracks
should be blown with compressed air to remove dirt accumulation (Fig. 8.21). Steel sub-
strates should be free of oxidation.
If epoxy is to be installed by the gravity method, horizontal cracks should be grooved
to form a V-shape. The groove should be blown out, to remove all concrete dust and other
contaminants before epoxy is placed in the groove.

TABLE 8.8 Epoxy Injection Properties
Advantages Disadvantages
Restores structural integrity Extensive installation requirements
Wood, metal, and concrete substrate No movement capability
High-strength May stain surrounding substrate