Polyurethane Pipe Grouting

Polyurethane pipe grouting uses either plural component geotechnical polyurethanes or prepolymers (single component polyurethanes) to repair large diameter pipes.

Plural Component Polyurethane Grouting

Plural component polyurethane pipe grouting uses rigid, geotechnical polyurethane grouts to stop leaks, seal infiltration and fill voids around pipes to stabilize them.  Plural component grouting works best in large, man-enterable pipes. 

Advantages of Plural Component Polyurethane Pipe Grouting

Plural component polyurethane grouts are better than prepolymer grouts in that they are structural, and lower cost.  We use the same plural component grouts for repairing large diameter pipe repair as we use for lifting industrial and commercial slabs, including railroad crossings.  This ensures that large voids around pipes are filled with strong material that won’t compress under the weight of the overlying soil.  Many prepolymers and single component grouts used for smaller diameter pipe grouting are not structural foams.

Plural component polyurethane grouts can also be injected into active water flows to stop them.  It’s important that hydro-insensitive foams are used for this application.  Very fast leaks can be stopped using plural component foams which react quickly.  

Limitations of Plural Component Polyurethane Pipe Grouting

Polyurethane pipe grouting repair in Petersburg, Virginia.

Polyurethane grout showing on surface from underground pipe injection.

A limitation of polyurethane pipe grouting using is that the curing process of polyurethane grouts generates heat.  This can cause the foam to scorch.  We use specially-formulated low exotherm foams for bulk void filling applications around pipes, which allows us to fill any size void without having to wait for the material to cool between stages.

Single Component Polyurethane Grouting

Single component polyurethane grouting uses prepolymer grouts which consist of a single foam component.  The foam component reacts with environmental moisture to expand and cure.  Accelerators can be used in varying concentrations to speed the reaction time of the curing process.

Advantages of Single Component Polyurethane Grouting

Single component polyurethane grouting is done with compact equipment.  Typically, all that’s required is a paint sprayer.  Equipment can easily be moved by people to remote sites where the larger equipment required for plural component polyurethane grouting can’t reach.  Examples include small dams that aren’t close to roads, long runs of pipes through woods, etc.  

Prepolymer grouts can also be injected through pipes driven into the ground, a process which is protected by patent when using plural component polyurethane grouts.  This can be used to repair joints in pipes which are too small to enter.

Prepolymer grouts don’t have worker safety or environmental safety concerns, unlike acrylamide grouts, which are popular in small diameter sanitary sewer pipe repairs.

Disadvantages of Single Component Polyurethane Grouting

Polyurethane pipe grouting  using single component prepolymer grout.

Polyurethane grout extruding through pipe joint.

Prepolymer polyurethane grouts tend to be much more expensive than plural component grouts.  Plural component grouts run around $20 per gallon for the raw material.  Prepolymer grouts start around $50 per gallon and some cost as much as $120 per gallon.