During construction of a data center in Richmond, Virginia, two bores were done under a roadway so that communication duct banks could cross into the facility. Each casing was 48″ in diameter, and approximately 100LF.
The jack & bore contractor was required to grout the annular space after sliding in the conduit bundles. The dense conduit bundles and relatively fragile pipes led them to doubt the ability of a traditional flowable fill grout to completely travel the length of the bores without damaging the conduits.
CJGeo proposed performing the annular space grouting using cellular concrete. CJGeo had perviously pumped cellular concrete on the same site more than 1600LF to abandon a run of 30″ sewer line, so the contractor knew that grouting 100 foot long runs wouldn’t be a problem for cellular concrete.
CJGeo mobilized a single cellular concrete crew to the site, and grouted two bores in less than a day. All of the grouting was completed at less than 5psi of grouting pressure. Both bores were confirmed full when uniform cellular concrete vented at the 12 o’clock position on the opposite side of the road.
38lb/cuft cellular concrete was used to meet the 28 day break strength requirement of 200psi. CJGeo used continuous generation to generate and place the cellular concrete; the whole project was completed using just two loads of ready mix slurry.