RCP Repair

Joint Sealing & Back Grouting

rcp repair contractor

Reinforced concrete pipe is one of the most structurally-durable pipes available for culverts.  CJGeo specializes in RCP repair–primarily in pipes large enough to enter, so 36″ and larger. We also grout around smaller diameter pipes if they are shallow enough to reach with sacrificial tubing driven from the surface. Leaking joints is the most common problem with RCP culverts & structures.  


Piping is when water flows outside of a culvert instead of through it.  Different things can cause piping, but the key to fixing it is making it easier for the water to flow through the culvert than alongside it.  There are two approaches to fixing piping as part of RCP repair; plugging the source of the water, and then filling its flow path.  Plugging is generally done with polyurethane grouting.  Polyurethane grouting is then also used for filling water flow paths along the pipe.  Sometimes, chemical grouting is used to solidify soils around the location of the water source.

We perform polyurethane grouting using plural component polyurethane grouts for reinforced concrete pipe repair.  Plural component polyurethanes are structural, closed cell rigid plastics.  This means the grouts we use to address piping don’t hold water, and have high bearing capacities.  This helps to ensure that once pipe is addressed, the corrugated metal pipe is structurally stabilized against movement.

Open Joints

Open joints in RCP pipes are a frequent cause of problems.  When a joint is misaligned, backfill material can erode into the pipe.  Open joints frequently result in the formation of sinkholes over RCP pipes, which can problems with adjacent utilities and transportation infrastructure & private structures.  

Joint sealing for reinforced concrete pipe repair is done using injected polyurethane grouting.  Sometimes, sprayed polyurethane-polyurea hybrid is used to seal open joints.


Voids are usually accompanied by piping & open joints.  Therefore, they’re addressed in the same way, using polyurethane grouting.  Sometimes there are exceptionally large voids outside of pipes.  It’s important in situations like this to use low-exotherm polyurethane grouts.  Reaction and curing of polyurethane grouts is an exothermic process (it generates heat).

CJGeo uses special, low exotherm polyurethane grouts, such as CJGrout 20SDB for bulk void filling.  This allows us to fill exceptionally large voids quickly while avoiding problems with heat.  Void filling is done by drilling holes through the wall of the pipe, and injecting polyurethane grout through the holes.  The grout seeks out voids as a liquid, then expands up to 30 times to completely fill the voids.  By using structural, plural component polyurethane grouts, the grout provides structural support for the pipe and the overlying soils and structures. 

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