Parsippany Annular Space Grouting

Parsippany Annular Space Grouting

Troy Hills, New Jersey

The Job

This Parsippany annular space grouting project is part of a microtunneled installation of 48″ sanitary line in two runs under an interstate. Each tunnel is 60″ diameter, one was 725LF, the other 530LF. They shared a shaft. The project’s goal is to replace an aging stretch of large diameter gravity sewer that runs parallel to the interstate.

The Challenge

The owner specified a grouted annular space for the tunnels. The long pumping distance and relatively tight annulus drove the need for a highly mobile, lightweight grout.

Cellular grout is advantageous for annular space grouting because:

  • it’s primarily air, so takes little energy (pressure) to pump, which virtually eliminates risk of damaging the carrier pipe(s) during grouting
  • it’s significantly lower density than traditional grouts, which reduces the buoyancy of carrier pipe(s)
  • cellular grout is made onsite, reducing risk exposures from the ready mix supply chain when mosts placements are “you only get once chance to do this right” type of jobs

The Solution

CJGeo placed 270CY of 35lb/cuft CJFill-ST (36ksf unconfined compressive strength) cellular grout to fill the annulus on both tunnels. Because the shared shaft wasn’t easily accessible, grouting was performed from each end towards the shared shaft over two back to back days.

CJGeo used onsite dry batching to generate the cellular grout for this Parsippany annular space grouting project. Dry batch generation uses bulk cement, eliminating risks associated with the ready mix supply chain. Cellular grout made using the dry batch process is also much higher quality, which allows CJGeo to get higher strengths with lower densities. This lowers pumping pressure, buoyancy, and costs.

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