Stabilizing Bridge Abutments and Approaches in Marion County

Project Background

In October 2024, the Marion County Engineer and Assistant Engineer reached out to Concrete Polyfix after learning about our advanced polyurethane application through email outreach. Their primary concern was the long-term stability of two county bridges located on a two-lane highway. The bridges were facing significant risks due to soil erosion and void formation, threatening potential structural failure.

Scope of Work

The bridges were experiencing severe undermining caused by:

• Poorly constructed weep holes in the abutments leaking backfill.
• Water runoff eroding soil under and around the bridge approaches.

Previous attempts to address the issue included injecting concrete slurry and applying riprap. However, these methods failed, with the slurry losing effectiveness within two years and the riprap washing downstream. Concrete Polyfix was tasked with providing a long-term, cost-effective solution to stabilize the backfill and prevent further erosion.

Challenges

The key challenges were:

• Addressing the erosion caused by water flowing through the weep holes and drainage areas.
• Stabilizing the backfill under the bridge approaches without risking further damage to the structure.
• Ensuring a durable solution where past methods had failed.

Solutions

Concrete Polyfix implemented a two-pronged approach using hydrophobic, expanding polyurethane foam:

1. Horizontal Void Filling
   Applied under the bridge approaches to stabilize the backfill, extending 8 feet back from the abutments.
2. Vertical Void Filling
   Injected into the abutments to seal voids and prevent backfill from leaking through the weep holes.

Results

• Cost Savings: The county avoided a costly bridge rebuild, estimated at over $500,000, by opting for our $7,200 polyurethane solution.
• Durability: The solution included a 5-year workmanship warranty and a lifetime product warranty, ensuring long-term reliability.
• Structural Integrity: The bridges were stabilized, with backfill secured against further erosion and undermining.

Conclusion

Concrete Polyfix delivered a tailored and cost-effective solution to Marion County, successfully stabilizing two critical bridges at a fraction of the potential replacement cost. Our advanced polyurethane application ensured long-term protection and peace of mind for the county engineers.