nc 48 inch rcp slide

48 Inch RCP Joint Repair

Raleigh, North Carolina

The Job

This 48 inch RCP joint repair project is located in Raleigh, North Carolina. The pipe is located at a commercial facility. The slope covering the pipe experienced a slope failure. Upon inspection, six joints were showing signs of soil infiltration and water exfiltration.

The Challenge

The primary challenge for the general contractor on this project was minimizing cost and time. It would have been expensive and disruptive to excavate the pipe. Cover depths were up to 15 feet, and there was a road that would be impacted by excavation, as well.

The exfiltration from the leaking joints was washing away bedding material and adjacent backfill. This caused significant amounts of erosion, and destabilized the slope soils by completely saturating them.

Piping outside of reinforced concrete pipe is an ideal candidate for polyurethane grouting.

The Solution

CJGeo worked with the general contractor and owner’s civil engineering to design a grouting program to repair the pipe. The general concept for this 48 inch RCP joint repair project was to backgrout the pipe with rigid geotechnical polyurethane grout. CJGrout 35NHV61 was the grout of choice; it can be injected directly into flowing water, provides nearly 10ksf in compressive strength, and migrates into both large and small voids with ease.

A CJGeo polyurethane grouting crew took a single day to perform the repair. The average circumferential void around the pipe was nearly nine inches. Cutoff criteria were:

  • grout hole to joint communication
  • cross hole communication

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