The Location:
Four miles north of Cuba, N.M., State Highway 96 is the only road into the Jicarilla Indian Reservation. Where this asphalt road crosses over an arroyo, a multi-plate culvert (14 ft tall, 21 ft wide and 115 ft long) was constructed 22 ft below the road surface to allow spring mountain runoff to drain away.
Culvert failures below roadways often cause problems for the road above. Washout and lost soils often result from the fast-moving, high-volume water flow through the culvert and the head pressure against the soils surrounding it.
By the Fall of 2002, the roadway above this culvert had settled as much as 6 in. NMDOT contracted Uretek USA to test the soils between the road and the culvert and around the culvert itself to identify any weak soil zones. While numerous penetrometer tests revealed strong base and sub base soils above the crown of this multi-plate culvert, they also revealed poor soil compaction and large, deep voids in several key weight-bearing locations around the culvert itself.
The Solution:
NMDOT contracted Uretek USA to both densify these weak soils around the culvert and to lift the asphalt road back to grade. To do this, Uretek chose its patented Uretek Deep Injection (DI) process, a powerful polymer compaction-grouting technique which provided NMDOT a long-term solution.
A key component of the Deep Injection process is Uretek 486, the company's high-density, hydro-insensitive polymer capable of expanding up to 20 times its original liquid volume. The material maintains its structural strength and integrity even in the wettest environments, making it ideally suited to areas where water has compromised surrounding soils. Within 15 minutes of injection, Uretek 486 reaches 90% of its ultimate strength, giving the Uretek techniques a decided advantage over competing processes.
While traditional DI applications are made from the surface, this situation indicated the Uretek 486 injections were also needed from inside the culvert itself, using a radial pattern (see diagram inset). Applying this approach to varied depths at different locations, the now densified soil was pushed upwards against the base material and the roadway by the expanding polymer, thereby returning the road to profile.
Small, 5/8-in. holes were drilled through the corrugated plates and the 486 material was injected at specific elevations along a predetermined grid pattern, which ran the length of the pipe. As the skilled Uretek crews worked their way down the culvert, the soils became stronger as the polymer's expansion filled the voids and compressed the weak areas. The entire project required only five working days to complete and the road remained in service during the entire project!
The Results:
After the last injection was made and the settled pavement raised back to grade, penetrometer tests revealed a substantial density increase in the soil above and around the culvert itself. In 2004, the asphalt road, some 3 ft outside the original Uretek Deep Injection zone, experienced minor settlement. The previously treated section remained in perfect profile. NMDOT again called Uretek, and within a few hours this portion of the road was also back in profile. This entire section of Highway 96 still remains level, and since 2002 NMDOT has continued to call Uretek USA to address similar soil densification and pavement lifting problems within the state.
The Summary:
When you're ready to control your soil stabilization and pavement lifting and infrastructure rehabilitation problems with a fast, cost-effective, long-term and environmentally safe solution, go to www.uretekusa.com/locations to find your nearest Uretek USA representative or simply call us at 888/287-3835.
