Roadway Void Filling


Void of unknown size discovered under roadway during open-cut utility installation on a military base, requiring roadway void filling.  During initial open cut, water was running out of void into utility trench.  Trench had been backfilled with stone dust after initial cut was made, and due to the original estimate of void size, it was likely that large quantities of backfill material had entered the void, which would have prevented adequate installation of void filling polyurethane.


Time limit of 24 hours from removing steel plates and backfill to completing pavement patching were allowed due to military readiness requirements.  Contractor had to backfill trench after void was discovered to reopen road, so exact conditions were unknown going into work.  

Due to potential unknown utilities under slab, no drilling through roadway slab was allowed.  The void was adjacent to two mission-critical conduit banks, so the repair area was very sensitive to disturbance.  No drilling or excavation was allowed.

The affected roadway was a designated route for moving heavy armor around the facility, so the void filling material had to have a high bearing capacity.


Roadway void filling using polyurethane grouting by CJGeoHigh density polyurethane grouting for the required roadway void filling.  Material was free sprayed from the open cut utility trench to fill the void without having to drill through the roadway slabs/asphalt overlay.  

Before polyurethane grout installation, high pressure, high volume air was used to remove the backfill material that had accumulated in the void.  The selected polyurethane grout had a 5 time safety factor for bearing capacity compared to calculated loads from tanks and other heavy traffic.


CJGeo polyurethane grouting crew cleaned the void of loose debris and installed high density polyurethane into void in less than two hours, allowing immediately backfilling of the open cut trench and subsequent pavement repairs, all within allotted time.  After the roadway void filling was completed, the general contractor was able to backfill the trench and complete the asphalt pavement repairs.