This would be the first time FDR would be used to treat a fly ash road. Ergon’s engineered emulsion — FDR-EE — was the selected binder for this process. This emulsion would help facilitate a stable base able to resist moisture damage while also serving as a strong bonding agent for fly ash particles. The FDR application would be followed by a prime coat to prepare and protect the newly constructed road base, and then a chip seal to facilitate return traffic and further seal out moisture, keeping the ground water from rising to the surface. A 1.5-inch hot mix asphalt overlay would be applied as the final wearing course for increased structural value and durability as well as a smooth, dust-free driving surface.
The County decided to move forward with a winter start date for the one-mile project in early January 2020. FDR, like other asphalt-based treatments, is not typically applied during winter months, as warmer temperatures and drier conditions are more suitable for both performance and production. However, Indigo Road needed immediate attention and the County was eager to see how the FDR-EE would perform. The FDR contractor, Ranger Construction, pulverized six inches of Indigo Road. The pulverized material was then mixed in place with Ergon’s FDR-EE, reshaped and compacted.
FDR-EE Mixture Stands Up to Traffic/Weather: Truck traffic was allowed back on the road immediately following application, as there was simply no other option. While it took one week for the mixture to reach optimal water content under consistently heavy rainfall, the FDR-EE mixture held up and withstood the same destructive truck traffic that had so badly deteriorated the previous road structure.
Once the FDR-EE had cured, Hudson Construction applied a prime coat using Ergon’s MC-70 at a shot rate of 0.10 gallons per square yard. Again, trucks traveling to and from the sand pit were back on the road immediately following application. Even under pressure from traffic and subjected again to heavy rainfall, the prime coat held up.
Cold and wet weather forced Hudson to wait a month before applying the chip seal using one of Ergon’s conventional chip seal emulsion products (CRS-2H) along with size 89 aggregate as the cover stone. The final stage of the project was completed the second week of March, when Preferred Materials Inc. applied the 1.5-inch asphalt overlay.
“This has been a huge success for the community and will be a great opportunity going forward for all involved,” said Neal Howard of UHK. “This could not have been accomplished without the efforts of Ergon Asphalt & Emulsions and Paragon Technical Services.”
Effingham County Road Department was impressed with how well Indigo Road held up under constant pressure, cold and extremely wet weather. Even though the treatments were placed outside the recommended seasonal application time and were subjected to heavy traffic immediately following application, the Board Members of Effingham County were very pleased with how well they performed. Note: When applied according to seasonal recommendations and without consistently heavy rainfall, this same treatment can be completed in weeks instead of a span of three months. Additionally, FDR applications using Ergon’s engineered emulsion are suitable for all types of roadways in need of rehabilitation.
The County was able to save big with the FDR process. At a centerline mile cost of around $560,000, the FDR treatment plan, including the subsequent treatments for additional durability and resistance, was less than half of that required to remove, transport and then reconstruct the road. If this same process could be used to treat all 900 miles of fly ash roads in southeast Georgia, state, county and city agencies would recognize a potential combined savings of over $800 million.
Long-Term Strategy: Realizing the success of the Indigo Road project, Effingham County plans to continue FDR-EE applications on other fly ash roads within their network.