What Is Chemical Grouting?

The chemicals used to repair underground wastewater pipes were first developed in the 1950s and ‘60s. Urethane grouts reacted with water and moist soil to form rubber-like balls that filled external voids or acted like gaskets in leaky joints. The technology was attractive because it was relatively inexpensive, easy to apply, and used non-toxic chemicals that did not cause problems in wastewater treatment plants.

At the same time, low-viscosity “solution grouts” were developed that could be applied using remote-controlled “packers.” Packers are inflatable plugs that isolate short sections of underground pipe so that grouts can be pumped into the section and forced through leaks and failing joints into the surrounding soil. Thus, chemical grouting became one of the first trenchless pipe rehabilitation solutions.While resinous,urethane-based grouts are used to repair leaky manholes, by far the majority of chemical grouts nowadays are used in a water solution, applied by truck-mounted systems,Packers can chemically-grout sewer mains up to 144 inches in diameter, while specialized packers can grout laterals up to around 30 feet from the main line.