Warner Springs

Cold Recycle Pilot Paving Project -

Showcases Different Paving Option For State Projects

By Tammy Boone

A two-mile stretch of California Highway 79 north of Warner Springs, California was the site in mid-April of a two-day pilot job for CalTrans, performed by CalTrans, Pavement Recycling Systems (PRS) and Petrochem Manufacturing, Inc. The job was a cold central plant recycling paving process.

In this type of process, the pavement is milled and then transported to a portable recycling plant within a couple miles of the project. The milled aggregate is screened and then reprocessed. The recycled cold mix is comprised of 100% recycled asphalt material, 1% Portland cement, about 3% emulsion and, in this case, Petrochem’s admixture. The ingredients are mixed at ambient temperature and the new cold mix asphalt is trucked back to the jobsite, put thru a paving machine and ends up as new pavement. Once the asphalt is rolled, a surface sealer is applied so that no overlay is needed.

Rick Turner, with his groundman Nate Martinez from PRS milled three inches of asphalt from the existing road surface with a CMI PR 500. The pavement was 11 feet wide.

CalTrans handled the trucking and paving operation for the project. PRS ran the recycling plant, with Jamie Emerson overseeing the work for PRS. PRS had six men on the job, four at the mixing plant and two responsible for the milling. CalTrans’ District 11 Area Superintendent and person responsible for putting the project together was Paul Von Normann. 

“Paul was instrumental in championing this innovative job process through the maze of the various CalTrans committees”, says Frank Hoffman, General Manager of Petrochem. 

According to Don Matthews, General Manager of PRS, the first mile of the project, which was completed on the first day, had some challenges.

“We experienced some mechanical breakdowns during day one which, required additional measures to provide a smooth wearing course,” he says. “With no mechanical challenges on the second day, the second mile went exactly as planned with excellent results.”

(Left) Applying diluted SS-1h Tack Coat. (Right) Grinder in process of grinding and loading Caltrans 10 yard Truck.

These challenges, he says, demonstrate the need to have the right equipment and backup equipment on the job.

 The admixture used in the process is the brainchild of Petrochem, owned by Bryan Burris. According to Bryan, cold recycling is not a new process, but Petrochem has come up with an additive that increases the early strength of the product to match that of hot mix asphalt.

“One of the critical factors of cold recycling is the time it takes to achieve initial strength,” Bryan explains. “Our product helps the mix to come to strength sooner.”

Petrochem has been using the additive for a number of years on smaller demonstration projects, but this is the first large job that the company has been involved with using this process for CalTrans.

Cold central plant recycling of asphalt has several advantages, according to Bryan Frank and Don. One advantage is the decreased trucking costs, as the cold recycling plant is capable of moving to a site close to the project.  For instance, for this job, the plant was within 1.5 miles of the project. 

“The mobility advantage makes this process a great choice for all jobs located far from a hot-mix asphalt plant,” Frank explains. “It offers big savings on trucking costs.”

“Traditionally, the milled material is trucked to a suitable landfill or recycle yard and then the hot mix is trucked back to the job,” he continues. “We saved more than $20 per ton in trucking costs alone on this project, which made this cold recycle process very cost-effective.”

Another big advantage to cold recycling is that it reuses what Don says are some of the best aggregate resources the state of California has already invested in.

“There is a shortage of aggregate in California and this process uses what is already there in the existing roads,” Don says.

Frank adds that, “there are billions of dollars of assets in our streets and roads. If you use those assets correctly, it can save a lot of money and natural resources.”

According to Bryan, this process of cold mix asphalt uses 100% of the recycled material, whereas hot mix typically only uses 15-50% of the recycled material.

This cold mix process also uses recycled rubber tires, which have in the past gone to landfills, Frank explains. Hence, it is a very environmentally friendly process.

Finally, the cold mix processing is much safer than the hot mix processing, because the mixing and laydown is done at ambient temperatures.  It does not have the heat and fumes associated with the hot mix process, Frank says. Additionally, there is not any equipment on the job that is hot, which help to prevent burn injuries.

Top to Bottom: First Picture : Trucks waiting in line to be loaded with grindings. Second Picture: Pre dawm grinding. Third Picture: Lay down and compaction of recycled asphalt. Fourth Picture: Application of Presentation Seal over recycled pavement. Fifth Picture: Paving with recycled asphalt.

The cold mix process compares favorably to the hot mix process say all those involved. Hot mix asphalt gets its strength within four hours, Frank says. Petrochem’s product has “improved initial early strength over old cold mix processes,” according to Bryan. “Our cold mix process compares very favorably to hot mix when looking at initial strength after four hours.”

Frank believes that as far as durability goes, the cold mix asphalt should last as long as the typical hot mix asphalt.

“Due to the higher early strength our product provides, there are not as many problems compared with older methods of cold mix recycle,” Bryan says.

“Cold mix recycle is often overlayed with a thin lift of hot mix,” he continues. “We are advocating foregoing the hot mix in favor of putting a surface seal on the cold mix pavement structure, which saves on money and resources.”

Pavement Recycling Systems offers a wide range of pavement rehabilitation strategies including cold milling; pulverizing; soil stabilization; soil mixing and treatment; cement and lime treatment of soils and pavement structures; cold, in-place recycling; and equipment rental. Pavement Recycling Systems operates throughout California, Nevada, Utah, Idaho and Arizona.

According to the company’s website, “PRS is committed to the belief that recycling is the best long-term solution to the pavement portion of our nation’s infrastructure challenges. Recycling and processing existing materials on-site provides an ecological alternative to traditional methods by minimizing export hauls, disposal costs and reducing truck traffic.”

Bryan’s father, Michael, started Petrochem. The company, whose main office is in Carlsbad, California, is a manufacturer of emulsion products. 

Petrochem is the industry leader in the development and marketing of rubberized emulsion aggregate slurry, receiving numerous national and industry awards for innovation in the use of recycled products. According to Tom Cheuvront, Petrochem’s Director of Marketing, the recycling of existing asphalt pavement presents another opportunity for Petrochem to bring to the market new technological advancements that provide governmental agencies the ability to conserve resources, thereby reducing their paving costs.

“My father really had the vision for the cold in place recycling process,” Bryan says. “He inspired the company to develop the technologies.  He saw Pavement Recycling Systems as a natural fit in helping to develop this process”

Frank says the company would like to see the cold mix process get a “good, solid foothold with this technology and application throughout the country. We do not believe this process should be used for every application, however, we believe our admixture combined with new cold mix recycle technology can create considerable savings of both natural resources and tax payers dollars without sacrificing quality.”

Steve Escobar and Bob Staugaard from Asphalt Pavement and Recycling Technology, Inc., (APART) located in Shafter, California, have played an intregal part in testing and developing mix designs used in the cold mix process.

“APART provides all the mix designs on our work, performs quality control testing, and offers technical support,” Bryan says.

Contact Petrochem at: (760) 603-0961. Contact PRS at: (800) 966-7774 or look on the web at www.pavementrecycling.com. Cc