The Details Of Chemical Grouting

Many of you have specified or used chemical grouting in one of your projects or are planning on using this technology to control groundwater infiltration into structurally sound sewer joints or recently lined sewer service connection cut-outs. Chemical grouting has been used for more than 50 years and has proven itself to be an effective method to control infiltration and exfiltration in sewers.

Often the capability and installation methods have been misunderstood and thus sometimes grouting has been used in projects with little thought behind the details that make this process work for you.

The most important aspect of chemical grouting is to recognize it is a pipe bedding soil sealing and stabilization process. Chemical grout works outside the pipe, beyond the point of mixing within the injection packer void located over the leaking joint. The objective is to pump the two-part chemical grout down to the point of injection where it is mixed within the packer/pipe void and force this mixed grout through a failed pipe joint into the pipe bedding soil adjacent to the leak. This same injection pressure grouting technique applies to lined pipe service cut out annulus and adjacent leaking service lateral connections. The grout stops groundwater flowing into the sewer through the bedding soil adjacent to the leaking sewer joint or through the annulus between liner and host pipe.

The most common chemical grouts being pumped through remotely operated packers are acrylamide, acrylates, acrylics (referred here as solution grouts) and urethane gels (referred here as the resin grouts). We will review some of the most critical points to consider before starting a project.