Whether it’s piping, open joints, voids, washouts or deteriorated inverts, CJGeo has solutions to fit your corrugated metal pipe repair needs.
Piping
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 culver than alongside it. There are two approaches to fixing piping; 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. 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 corrugated metal pipes are a frequent cause of problems. When a joint is misaligned, backfill material can erode into the pipe. Corrugated metal pipes are dependent on proper backfill for structural integrity. Therefore, when joints aren’t tight and backfill can erode into the pipe, the integrity of the pipe is compromised.
Injection seals joints against soil & water infiltration. Sprayed coatings seal against water exfiltration.
Voids
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, like 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.
Washouts
Washouts outside of corrugated metal pipes are relatively common. Small amounts of piping and voids can escalate into washout conditions where the overlying soil collapses. We use polyurethane grouting for washout corrugated metal pipe repair. Low exotherm polyurethane grouts are important in situations like this. Structural foams are also important, as single component foams in large voids can lack the required strength to stabilize the pipe & surrounding ground.
CJGrout 20SDB is excellent for filling dry washout cavities. CJGrout 35NHV61 is excellent for filling washout cavities with standing water.
Deteriorated Inverts
Deteriorated inverts are one of the most common problems with corrugated metal pipes. Sometimes, pipes are properly installed and maintained and never develop piping or voids. However, over time, the protective coatings, such as galvanizing or aluminizing are abraded, exposing the the steel pipe to water. This usually happens at the invert, where flow with suspended solids is the most prevalent. Over time, the invert of the pipe rusts, eventually rusting through.
During low flow conditions, it’s pretty common to see pipes with corroded inverts have water flowing through parts of the pipe that then disappears through a corroded area and then reappears a few feet further down the pipe out of a corroded area. After an invert has corroded completely, the deterioration of the culvert system is greatly accelerated. This can result in complete failure, including collapse of the pipe.
Deteriorated inverts can be repaired a number of ways. Inverts can be paved with concrete, which essentially creates a new pipe floor using reinforced concrete. If invert deterioration is localized, installing special concrete blankets in the invert to stop abrasion of the pipe can be done. Sprayed coatings may also be used for corrugated metal pipe repair to address corroded inverts.
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