The Job
This Pennsylvania permeation grouting project is one of the rare projects where polyurethane serves as the best permeation grout. Typically, CJGeo perform permeation grouting using water-like grouts, such as acrylate or colloidal silica. This project at a Lehigh Valley distribution center occurred because expansive shale heaved the interior floor up to nearly a foot. To address this, the consulting geotechnical engineer called for grouting a curtain along the exterior of the building through the 57 stone and blasting-disturbed rock along roughly 700 feet of the building.
They also removed all of the affected expansive shale fill inside the building and replaced the floor slab.
Drilling & grouting.
The Challenge
This job presented two primary challenges. From an operations perspective, the grouting work couldn't tie up more than 6 docks at a time. From a functional perspective, the grout needed to be highly mobile, dimensionally-stable, water-proof, and contain as little water as possible.
CJGeo proposed dual-component polyurethane grouting, using CJGrout 20SDB. We recommended 20SDB because of its exceptionally high mobility, even through stone beds and small fissures. It contains no water and effectively blocks even water vapor.
The Solution
Sonic drilling to facilitate grouting.
While air rotary drilling would have kept all water out of the process, it proved too dirty for the food storage environment. After drilling a few test holes, CJGeo self-performed all drilling using sonic equipment. CJGeo utilized sonic drilling to drill every two feet down to competent rock. The crew socketed the grouting 1.5 feet into the underlying competent rock.
After CJGeo drilled each grouting location, the holes stood open. This stability allowed CJGeo to drop polyurethane grouting tubing down each hole. The team pumped the polyurethane grout continuously on retraction. Widespread cross-hole communication served as the primary cut-off criteria, along with return to the surface.
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