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Pima County DOT's real life pavement testing area

San Joaquin Road near Old Ajo Highway chosen
Posted: 11:09 AM, Jul 24, 2018
Updated: 2018-07-24 17:09:29Z

  Something unique is on the way that will hopefully help the county transportation department find the best combination of asphalt paving for our area for the best price. It's informally being called a "pavement test" and will start after Labor Day on a road west of town. There are over a dozen combinations of pavement that will be applied to San Joaquin Road, between Old Ajo & Milky Way Drive, on Tucson's west side.

The various paving products will be applied in 1000 foot segments, back-to-back, spanning over 4 miles. Pima County DOT's Paul Bennett is tasked with the project construction and says by having all the products in one area for their analysis, it will be an "apples-to-apples" comparison.

Bennett adds that materials laboratories will begin seeing data on the different sections' performance after the first six months. Testing will occur every six months after that, for the next several years.

Some of the paving products to be used:

* 1 inch "Green Asphalt" over existing pavement.

* 2 inches overlay of existing "PAG 2 mix" (PAG 2 is the most common asphalt mixed used in the metro region).
* 2 inches overlay of existing "PAG 2 mix w/ Terminal Blend" (asphalt mix blended with dissolved rubber).
* 1 ¼ inches overlay of existing with "PAG 3 Terminal Blend" (PAG 3 is a smoother and finer version of PAG 2).
* 2 inches overlay of existing PAG 2 mix with fiber.
* Pulverize 5 inches and compact with "Cape Seal" (chip seal plus slurry seal).
* Pulverize 5 inches and compact with chip seal.
* Pulverize 5 inches and compact with cement and chip seal.
* Pulverize 5 inches and compact with cement and chip seal.
* 6 inches roller-compacted concrete.
* Double chip seal over existing surface.
 
Tucson Asphalt's President Paul Polito developed a more environmentally-friendly product and patented it. His "Green Asphalt" is one of the paving treatments selected by the county for testing. Polito says his product lasts longer than many other asphalt treatments and is applied right over the top of the existing road, saving time. The company has recently treated several Bisbee streets with their product.
 
Bennett says cost will play a huge factor in determining the products Pima County will select and use in upcoming work. Residential streets may have a different type of pavement applied than a road with heavier traffic volume or vehicles carrying heavier loads.