A 30″ brick sewer in New Jersey started to unravel during an open excavation point repair. The municipal engineer directed the utility contractor to use welded HDPE pipe to reline the sewer instead of finishing the open cut point repair. This North Jersey annular space grouting project is located in Paterson, New Jersey.
The HDPE slip lining contractor had four requirements for grouting.
- No more than 10psi grouting pressure, as measured at the bulkheads
- A mix which minimized carrier buoyancy
- Three day turnaround from notification to completion
- 200psi strength at 28 days
CJGeo proposed 38PCF wet cast density cellular concrete for the annular space grouting. Cellular concrete is highly flowable. High flowability ensures low installation pressure. 38PCF cellular concrete reduces exerts 60% less buoyancy force compared to traditional weight grout. 38PCF cellular concrete reaches approximately 250psi at 28 days.
CJGeo mobilized to the site with two days’ notice. The CJGeo cellular concrete crew used continuous generation to generate and place the 38PCF cellular concrete to complete this North Jersey annular space grouting project. Peak pressure at the bulkheads never exceeded 5psi. All 500LF of the annulus was grouted in a single day, between four different manholes (three sections).