Sustainable Pavement Rehabilitation: FDR with Cement on FM 2185

Project Overview

The FM 2185 road rehabilitation project, a Texas Department of Transportation (TxDOT) project in the El Paso District, spanned close to 15 miles, addressing extensive cracking, rutting, and base failures that had significantly impacted roadway performance. The existing pavement consisted of 5 inches of flex base and 2 inches of seal coat, which had deteriorated significantly over time. Rather than using traditional mill-and-overlay techniques, which posed long-term cost and durability concerns, FDR with cement was selected as the preferred reconstruction method. The project involved mixing the existing pavement materials with new base materials and stabilizing them with 3% cement to a depth of 6 inches, along with a 4-foot shoulder widening and a seal coat treatment.

Figure 2. Reclaimer Processing FM 2185 Roadway (Provided by El Paso District, TxDOT)

The goal of the project was to enhance structural capacity, reduce maintenance needs, extend pavement service life, and improve safety and ride quality. The application of cement stabilization ensured a more uniform and resilient base layer, improving the roadway’s ability to withstand traffic loads and environmental stresses.

Implementation and Key Features

The rehabilitation of FM 2185 involved:

1. Material Processing: The existing pavement and base materials were reclaimed and blended with new base material to create a homogeneous layer.
2. Cement Stabilization: A controlled amount of cement (3%) was introduced to enhance the strength and durability of the new base.
3. Compaction and Finishing: The mixture was compacted to achieve optimal density, graded for smoothness, and cured before applying the final asphalt surface.

The TxDOT El Paso District conducted extensive testing on the existing subgrade and base materials to ensure optimal stabilization. Subgrade evaluations included Atterberg limits and particle size analysis, while the existing base underwent particle sieve analysis. Based on these comprehensive tests, engineers determined that a 3% cement content would provide sufficient strength and durability for the new base. Below is a laboratory-compacted specimen developed in the TxDOT El Paso District lab, representing the stabilized base material.

Figure 3. Laboratory-Compacted Specimen – 3% Cement-Stabilized Base (Provided by El Paso District, TxDOT)

Sustainability and Cost Savings of FDR

One of the key advantages of FDR with cement is its ability to reduce material waste, transportation costs, and fuel consumption compared to traditional reconstruction methods. By reusing existing roadway materials, FDR minimizes the need for new aggregate and hauling, leading to significant cost savings and environmental benefits.

Figure 4 compares the resource demands of FDR with cement versus new construction for a 1-mile, 24-foot-wide, 2-lane road with a 6-inch base, highlighting the reductions in truck trips, material use, waste disposal, and diesel consumption.

Figure 4. Comparison of Resource Use: New Construction vs. FDR (Data Sourced from the Portland Cement Association)

Challenges and Adjustments

Despite the successful execution, the project encountered some unexpected challenges that required on-site adjustments:

• An unexpected box culvert was discovered, requiring modifications to the construction schedule
• Base failure issues on the shoulder led to localized patchwork repairs
• Micro-milling was conducted to improve ride quality and ensure a smoother final surface
• Dust control and water ponding concerns arose, particularly at low-water crossings. To mitigate these issues, additional fill material was placed on the Right of Way (ROW) to reduce ponding and improve drainage

Advancing FDR with Cement: Research Collaboration with UTEP

To further enhance the understanding and implementation of FDR with cement, the Cement Council of Texas has partnered with the University of Texas at El Paso (UTEP) on a research initiative focused on the durability and early-age performance of cement-stabilized reclaimed bases. This study aims to provide critical insights into how FDR with cement bases perform under heavy traffic conditions and to refine guidelines for opening times to ensure both construction efficiency and long-term pavement performance.

Through laboratory testing and full-scale field evaluations, researchers at UTEP are investigating:

• The early-age strength gain of FDR with cement bases.
• The impact of heavy traffic loads on stabilized layers before final surfacing.
• Optimized curing times to balance construction schedules with pavement durability.
• Best practices for mix design and compaction to enhance resilience.

This collaboration aligns with TxDOT’s ongoing efforts to implement cost-effective, long-lasting pavement solutions, particularly in regions like West Texas, where roadway rehabilitation is critical for supporting economic activity and freight movement. The findings from this study will help refine construction specifications and guide decision-making for agencies considering FDR with cement as a sustainable and high-performance alternative to traditional rehabilitation methods.

Conclusion

The FM 2185 rehabilitation project showcases the effectiveness of FDR with cement in delivering a cost-efficient, durable, and resilient roadway solution. By addressing structural failures with 3% cement stabilization, TxDOT enhanced the pavement’s longevity while minimizing future maintenance. Building on this success, ongoing research at UTEP is set to improve our understanding of durability and early traffic opening for FDR with cement. These insights will help further optimize construction timelines and performance under heavy traffic conditions, reinforcing FDR as a sustainable and high-performance pavement rehabilitation method.