The treatments will be laid in multiple 1,000-ft. test sections covering both directions of traffic.
A 4.3-mi. section of San Joaquin Road between Old Ajo Highway and Milky Way Drive has been selected as a testing ground for several pavement treatments.
Twelve different treatments will be tested for various factors to ascertain life-cycle return on investment leading to more cost-effective selection of pavement treatments for use in Pima County.
The treatments will be laid in multiple 1,000-ft. test sections covering both directions of traffic. Pima County will group the treatments by color and texture to minimize the visual patchwork. The balance of the roadway will be repaved by removing 2 in. of existing asphalt and replacing it with 2 in. of traditional asphalt. The result will be the complete repair of a 4.3-mi. section of roadway that has fallen into poor condition.
The Department will evaluate the wear to test segments every six months, and forecast performance each treatment over time. The County also will study the road over several years to determine the best, most cost-effective and long-term treatment options. Construction is scheduled for this summer with treatments to include:
- 1 in. green asphalt over existing
- 1 ¼ in. overlay of existing with PAG 3 Terminal Blend
- 2 in. overlay of existing (PAG 2 mix)
- 2 in. overlay of existing (PAG 2 mix with fiber)
- 2 in. overlay of existing (PAG 2 mix terminal blend)
- pulverize 5 in. and compact with cape seal (chip seal plus slurry seal)
- pulverize 5 in. and compact with chip seal
- pulverize 5 in. and compact with cement (300 psi) and chip seal
- pulverize 5 in. and compact with cement (500 psi) and chip seal
- 6 in. roller compacted concrete
- double chip seal over existing
- rubberized chip seal over existing
- 2 in. mill and fill (PAG 2 mix)
Evaluation of the test treatments are scheduled to occur six months post construction and at annual intervals thereafter. Observations will include: cracking, rutting, oxidation, surface wear and roughness, supplemented by the regional Pima Association of Governments/city of Tucson Automated Road Analyzer van and additional laboratory tests as needed.
Treatment-specific curves will be developed based on data from each evaluation interval to rank treatment benefit-cost projection based on standardized return on investment criteria. These curves will be correlated against longer-term national research data for that treatment type, to infer longer term performance from shorter observation periods. The treatment curves will be controlled to account for minor localized variations in soil or drainage conditions.