Case Studies- Soil Stab & Void Fill Pages

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Asphalt highway stabilization with polyurethane

Asphalt highway stabilization with polyurethane provides a long-term solution to an ongoing settlement problem, keeps a busy interstate highway open during repairs.


Contractor: Applied Polymerics
Client: North Carolina DOT



A section of I-40 in the Winston-Salem, N.C. area had settlement issues. A stretch of the asphalt highway leading up to a bridge approach slab repeatedly experienced settlement, causing a dip in the road. The DOT kept having to repave that section only to have it sink again. It is likely that old organic fill underneath the highway decomposed over the years leaving voids and loose soil.

As a result, the DOT decided to solve the settlement issue once and for all and then complete a full repaving project. The DOT wanted to ensure it wouldn’t have to keep repaving that one section repeatedly.



The DOT contracted Applied Polymerics to stabilize the soil beneath the stretch of highway using polyurethane resin so that it would stop settling. The reconstruction alternative was not really a viable option since that would require closing the busy interstate highway. The Applied Polymerics crew drilled a grid pattern and injected the soils underneath with Prime Flex 910, a single-component, moisture-activated polyurethane resin.

“We did permeation grouting below the asphalt roadway,” said project lead Scott Kammerer. “We chose that product as the best option because no lifting was required, just stabilization. After injection, the DOT would not have to worry about further settlement.”

Prime Flex 910 is a super low viscosity resin, allowing for thorough penetration of the voids and loose soil under the highway. The resin reacts with moisture present in the soil and cures quickly to form a hard, water insensitive mass. The consolidated soil provides proper support for the structure above.



“Everything went well,” said Kammerer. “This was a pretty standard soil stabilization job. The project ultimately required approximately 900 gallons of material.  That section of highway remains stable, without settlement, years later.