Manhattan Floor Void Fill

Challenge:

During a Local Law 11 inspection, the owner of a coop building’s first floor asked the GC to investigate a settled slab floor inside part of the building.  The contractor started to open up a 2′ square hole in the floor, and noticed that all the debris was disappearing.  After opening the hole it was apparent why–a 2′ to 3′ deep void around the entire perimeter of the building footprint.

Limits:

Filling a 90CY void under the floor of an operation business can be challenge.  Complicate it with a 40′ x 10′ laydown area, Mid-Town Manhattan traffic, and cold winter temperatures, and you’ve got quite the challenge.  

The presumed cause of settlement was consolidation of poorly placed fill, which was primarily construction debris.  Lightweight void filling material was required to minimize future settlement of the underlying fill material.

The Solution:

At the suggestion of an on-staff structural engineer, the general contractor’s project manager reached out to CJGeo about performing polyurethane grouting to fill the voids.  CJGeo proposed using a low-exotherm, high mobility bulk void filling foam to fill the voids.  3′ deep voids are too deep to be filled with most polyurethane grouts; a true low exotherm foam is needed for efficiently and safely filling any voids thicker than about 6″.  High mobility foams are also critical when filling voids in order to ensure complete coverage.

Result:

CJGeo mobilized a two reactor polyurethane grouting rig and installed approximately 4800lbs of 2PCF polyurethane grout over a two day period.  CJGeo pulled continuous negative pressure on the void through the floor in order to allow for continuous operation of the facility during grouting.  There was zero disruption to the facility’s operations, and the voids were filled completely.