For epoxy applications, ports are set directly over or into the crack. Epoxy is injected directly into the crack. A low viscosity epoxy needs to get at least 90% penetration and fill of the crack for a structural repair. It is not necessary to drill into the crack to set the ports for epoxy injection. “Top Hat” ports can be used to set and seal cracks. This seal creates a reservoir for the epoxy by not allowing any of the resin to leak out during and after injection.
Polyurethane crack injection is done differently. Holes are drilled at a 45 degree angle to the crack in an attempt to meet the crack at its mid-point in the concrete membrane. Injecting the grout into the mid-point of the crack allows for expansion in all directions for a complete seal.
For polyurethane curtain wall grouting, holes are drilled completely through the wall in a pre-determined grid pattern and ports are set for the injection site. This method allows the crack or joint to be sealed from behind the wall. It is important to make sure you know where the steel reinforcing, possible post-tensioned cables, electrical conduit or any other systems that may be in or behind the wall are before drilling.
As mentioned in a previous blog, Polyurethanes vs. Epoxies, there are many different situations requiring either product type. The choice depends on the project at hand and the depth of your product knowledge.