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CIR + Chip Seal In Mitchell County, Kansas Is A Safe, Effective Rehabilitation Solution

In terms of safety, it became clear that a typical solution such as an asphalt overlay would not be acceptable. Though quick and simple, this solution would result in drop-offs too high to meet federal guidelines and too dangerous for the traveling public. Mitchell County needed a solution that would not alter Glen Elder Road’s surface elevation.

Given this information, and upon evaluating the core provided by Coughlin and the mix design provided by Paragon, it was decided that a 4-inch CIR finished with an appropriate chip seal would be optimal.

In stark contrast to a mill and fill, the total cost for this option, including materials and workmanship, was approximately $102,000 per centerline mile — at $87,000 per centerline mile for the CIR plus $15,000 per centerline mile to install the chip seal. That’s a savings of $68,000 per centerline mile over the mill/hotmix option.

In addition, the CIR option would address cracks down to 4-inches deep, whereas the mill and fill option would only address the top two inches of asphalt. According to industry standards, where cracks return on average one year later per inch of material, the CIR option is expected to manage cracking twice as long as the traditional mill and fill solution.

Application Highlights

During the CIR process, four inches of the existing pavement on Glen Elder Road were milled, mixed with Ergon A&E’s CIR emulsion, and then replaced.

Following the CIR process, Ergon’s CRS-1HP chip seal emulsion was applied at a shot rate of 0.35 gallons per square yard with ½-inch quartzite aggregate chips. Chip seals are typically applied following CIR applications to serve as wearing courses and/or to address any surface irregularities.

Ultimately the safest solution for any road is a solution that lasts. By using CIR finished with a chip seal, Mitchell County was able to reduce the cost of the treatment while increasing its efficacy, reduce construction time, keep motorists safe, and keep the traveling public away from unsafe drop-offs.

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Cold In-Place Recycling

According to the Asphalt Pavement Alliance, asphalt is recycled at a greater rate than any other material in the United States. Treating pavements with recycled asphalt is less costly than paving or repaving with new asphalt, and is a more environmentally friendly approach.

Environmental Impact

Recycled asphalt processes result in reduced emissions because they require less trucking and less energy during construction and have a smaller carbon footprint due to the fact that aggregate is reused. Of the recycling methods available, Cold In-Place Recycling (CIR) has perhaps the greatest environmental impact, as it can address cracking and restore pavement without the use of heat. This is a significant benefit for both the environment and construction crews because it reduces pollution and exposure to fumes.

The CIR Process

During the CIR process, existing pavement is milled at depths ranging from three to five inches. This material is crushed, mixed with a recycling emulsion and other additives as needed, replaced and then compacted.

This process allows for an energy efficient, cost-effective and timely solution for renewing your pavements. According to pavementineractive.org, CIR treatments are most effective when applied in “sunny, dry conditions” that allow the additives to set properly, which made it a fitting solution to treat an aged section of State Route 247 in San Bernardino, California — an area known for its dry climate. Following are details about this project as featured in June 2019 (No. 50) edition of CP2 Center News, a Newsletter of the California Pavement Preservation Center.

CIR in San Bernardino County

By: Marco Estrada, PRS

On State Route 247 near Lucerne Valley in San Bernardino County, Pavement Recycling Systems (PRS) performed Cold In-place Recycling (CIR) on over 230,000 SY of old asphalt pavement. The distresses in the existing pavement were block cracking and alligator cracking, but the underlying base showed no signs of failure, which made this the perfect candidate for CIR. The project required 3.5” of CIR with a 2.5” RHMA cap on top. The CIR process has an incredibly small ‘footprint’ that allows for minimal lane closures and a reduced impact to the regional traffic. Traffic was fully opened at the end of each day and in between the CIR and RHMA processes. Matich Corporation led the project as the Prime Contractor as well as the supplier for the rubberized hot mix asphalt (RHMA) that would overlay the CIR. Ergon Asphalt & Emulsions supplied the emulsion for the CIR process. The emulsion used was a CIR- EE mixed in at a rate of 2.75%.

PRS used a Caterpillar PR-1000 milling machine as part of their CIR train of equipment. The cold, wet CIR mix was deposited in a windrow for placing with a Caterpillar AP-1055 paving machine. Rolling was done with a 25-ton rubber-tire roller and Caterpillar P380. Overall, the project consisted of 19 days of CIR work and 18 days for the RHMA overlay, both portions were completed fully on-schedule.

Using CIR and recycling all the old asphalt pavement in-place not just cuts out the need to produce virgin asphalt by reusing materials in- place, it also reduces or eliminates the need for hauling of materials offsite. In total, this project eliminated approximately 4,000 truckloads of material, which greatly reduced traffic and CO2 emissions. This was not the only positive environmental impact provided on this project; the use of RHMA eliminated roughly 70,000 tires from landfills.

Mike Ristic, the Maintenance Engineer for Caltrans District 8, is no stranger to the CIR process. He talked about his experiences with the process, “2011 was when we started our first CIR project with SR 62 and US 95. Both projects came out great, as well as every CIR project we have done over the years. Overall, in District 8, we have done over 200 lane miles of CIR and plan to add more lane miles every year.” He went on to talk about the benefits of using CIR, stating that, “The pavement life that we are getting out of our recycled roads is 15 years or even more. We keep them maintained with seal coating to make sure that we get even more years of performance.” Referencing Caltrans’ goals for sustainability, Mike adds, “CIR is great on these projects because we recycle our existing pavement resources and eliminate the hauling of materials to asphalt plants that are typically 50 or more miles away. All results from CIR are very positive. The process is quicker (when compared to remove and replace methods) on the projects that we selected, and the final surface rides very smooth.”

As is with all Caltrans projects, there was a smoothness requirement for a Mean Roughness Index (MRI) of 60 or lower using IRI measurements. The paving operation was highly efficient utilizing best paving practices and grade controls on paving equipment and the final pavement surface obtained the required smoothness, exceeding the requirement with minimal corrections needed. The project also required the use of Intelligent Compaction (IC), to achieve a longer life by achieving more uniform and better overall compaction of the CIR and RHMA. IC Rollers utilize GPS mapping, which allows the operator to view the precise location of where compaction has been completed or areas that require further rolling. This makes sure that no areas of the mat are missed during the compaction process, which ensures adequate support, stability and strength leading to a long-lasting road.

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Restore Worn Asphalt Pavements With Cold In-Place Recycling

Cold In-Place Recycling Application

Background

When faced with roads like US 40, plagued with 10 miles of aged and cracked pavement, the Utah Department of Transportation (UDOT) realized Cold In-Place Recycling (CIR) was their most affordable option – but issues with another company’s emulsion had caused negative impressions toward the treatment within the state. That’s when Ergon Asphalt & Emulsions, Inc., (Ergon A&E), understanding the full potential of CIR, stepped in to help put the treatment back in the game. It was expected that through the collaborative efforts of Ergon A&E, UDOT and CME Transportation Group (CME), a third-party lab located in Salt Lake City, UT, that an all new specification for CIR would mean not only an affordable treatment for addressing worn pavements, but also one that could stand the test of time.

CIR is a process where two to five inches of existing pavement is pulverized into smaller pieces (1½” minus). This smaller material is mixed with an asphalt emulsion designed according to specific road types and needs. CIR is convenient when the project is in a rural or remote area, as emulsion does not need to be stored or applied at the same temperature as hot mix. CIR projects also require fewer trucks than typical reconstruction or mill and fill, where trucks would be needed to remove existing pavement and then to deliver new aggregate.

UDOT and CME worked with Ergon A&E to reevaluate criteria for CIR mix design procedure and requirements as well as construction specifications.

Giving CIR Another Chance

The new specifications were put to the test on the 10 miles of cracked HMA on US 40 in Uintah County. The area had been treated with numerous chip seals in the past, but the highway had deteriorated to the point that more aggressive action was needed.

The only options available to restore the HMA were CIR or full reconstruction. CIR was the most cost-effective of the treatment options, at approximately 30% to 40% less than full reconstruction. UDOT decided to try the new specification along with a layer of micro surfacing over the CIR, to provide a good wearing surface. Ergon A&E was chosen to supply the CIR emulsion.

This would be the first CIR project using the new specifications, so the results would be crucial in determining whether or not agencies would consider this product for future projects.

Application Highlights

The existing asphalt was milled to a depth of three inches and mixed with an average of 2.9% emulsion, 1.0% lime and 0.5% cement, then reapplied to the roadway. While the CIR would have been successful without added cement, curing and gaining strength within three to four hours, cement was added to help drive water out of the mix and create a faster break time during cooler temperatures.

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A WIN for CIR

CIR has been redeemed. UDOT was so pleased with its performance on US 40 that they added three additional CIR projects following this application. The success of CIR under new specifications has since proven to be a worthwhile and consistent solution for agencies.

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