The International Society for Trenchless Technology

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Joint Grouting
Grouting can reduce or eliminate inflow and infiltration of sewer lines and manholes by stabilizing and sealing the defect and the adjacent soil where the defect is not sever and the surrounding soil is stable enough to retain the grout. Grout can be applied over a large area such as manhole to manhole or at specific points along the mainline or at lateral joints. Epoxy resin or mortar is used in grouting localized defects. A chemical mix is used for flood grouting of a large section of sewer mains and laterals. In both cases the host pipe should be cleaned.

Localized grouting involves the use of inflatable packers, sized to the section of the pipe or service connection, to isolate the joint to be grouted from the rest of the sewer system allowing the controlled application of grout only to the part of the sewer sealed off by the packer. The packer initially is pulled into position over the joint or connection containing defects where it is inflated sealing off the area for grouting.  Pipes feed grout to the packer, where injection ports located in the area of the packer isolated by the packer and the pipe wall inject grout under pressure into the packer/pipe cavity, defects and soil outside the pipe surrounding the defects.

There are a variety of chemical grouts used for grouting of pipe joints and sewer connections. The grout should be compatible with the pipe materials and soil conditions surrounding the defect. To avoid clogging the feed pipes, two part epoxy resin grouts are fed to the packer in two pipes where it is mixed just prior to injection.

Joint Grouting

Once the space around the packer and the defect is filled with grout, and the soil surrounding the defect is saturated, the grout is held under pressure until it hardens in place forming a thin layer of grout on the pipe walls and a grout plug in the defect and the soil adjacent to the defect. After the grout has hardened, the packer is deflated and removed from the pipe and service restored.

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by pavoneggi