CIR and FDR in California City, California
November 11, 2010
On October 1st, 2010, I visited a CIR/FDR project in California City, California. The town has a population of approximately 15,000 and is located in Kern County, about 40 miles north of Palmdale and Lancaster. The photograph above was taken along California City Boulevard, the road that links the town to Highway 14. Closer to town the road turns into a four lane divided highway. The desert climate has taken its toll on the roadway: oxidation, thermal cracking, longitudinal and alligator cracking, are easily seen as shown in the next photograph.
To learn more about the project, I talked to On Man Lau, P.E., G.E., Branch Manager with BSK Associates. The City had a limited budget for the rehabilitation of California City Boulevard. Following an initial pavement investigation in which On Man was involved, HELT Engineers, the firm that provides engineering services to the City, performed a life cycle cost analysis and compared several rehabilitation alternatives: crack sealing and overlay, crack sealing + fabric + overlay, cold in-place recycling + overlay, and full depth reclamation +overlay. Based on the existing pavement condition and the economic analysis it was decided to recycle 1.5 miles of roadway and to use full depth reclamation on approximately 1 mile of California City Boulevard.
Bowman Construction was the general contractor for this project. On the areas selected for cold in place recycling, 4 inches of the existing pavement were milled and recycled. The mix design was done by Asphalt Pavement and Recycling Technologies. The recycling train is shown in the next photograph.
As shown above the cold millings mixed with emulsion are placed in a windrow ready for paving and compaction. According on On Man, the recycled mix was allowed to sit for about 24 hours before paving.
The final step, paving of the recycled mix is shown above. Below, on another stretch of California City Boulevard, a mixer/reclaimer is used for full depth reclamation.
On the areas selected for full depth reclamation, the contractor milled and treated 6 inches of the existing pavement with 4.5% to 5% emulsion and 1.5% Type II portland cement. Both CIR and FDR sections will receive a 2 inch overlay.
Shown below is a photograph of the completed project taken a few months later, in February 2011. The Pavement Recycling and Reclaiming Center will visit again the project in the near future to observe and document the performance of the CIR and FDR technologies in California City.