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OCR for page 9
9 One scheme for looking at available hours is to divide avail- partial- and full-depth repairs and for dowel bar retrofitting, able closure times into three groups: less than 12 hours, 12 to longer closure times are required for the material to reach 60 hours, and more than 60 hours. These groups are approx- acceptable strength. On the other hand, use of high early imately equivalent to an overnight closure, a closure between strength PCC mixes and fast-track proprietary repair materi- one-day and one-weekend long, and a closure that is longer als (and precast full-depth repair panels), usually enables than a weekend, respectively (Peshkin et al. 2006), although these preservation treatments to be used in single-shift or these ranges would vary based on local patterns of use, peak- overnight closures. hour rates, and so on. The survey feedback provided valuable information to Expected Treatment identify facility closure times that State agencies typically use Performance when performing preservation treatments associated with high-traffic-volume roadways (see Tables 2.9 and 2.10). Most Expected treatment performance also influences the selection preservation treatments on HMA-surfaced roads can be of a preservation treatment. There may be higher expectations completed within a single shift or overnight closure. Specifi- for treatment performance when there is more traffic because cally for HMA pavements, the overnight closure time was the higher-traffic-volume roadways are expected to last longer. It most frequently selected available scenario under which 12 of is also harder to gain access to roads with higher traffic vol- the 13 treatment alternatives are typically applied. The meth- umes, which contributes to the expectation that any work done ods most widely used with this length of closure include crack on such roads should last longer. Also, as noted, there is a filling, crack sealing, slurry seals, microsurfacing, chip seals, greater risk associated with a premature failure on such roads. ultra-thin bonded wearing courses, thin and ultra-thin HMA The measure of expected treatment performance used in overlays, cold milling and overlay projects, and profile milling. these guidelines is expected treatment life in years. To clarify, It should be noted that most of these treatments are used this does not refer to how long the treatment "lasts," but under the same available work hour scenarios for both urban rather to how long the treatment serves the purpose for which and rural areas. Hot in-place and cold in-place recycling are also it was placed (i.e., provides a benefit). Since the purpose of used as single shift or overnight projects, but less frequently preservation is to extend the life of a pavement, treatment than the previously listed activities. Finally, ultra-thin whitetop- performance must be measured in terms of the extension in ping is more often performed as a weekend or extended closure service life imparted to the existing pavement by the treat- project. ment. This designation of performance is most compatible Many pavement preservation techniques for PCC can be with the procedures needed to evaluate the cost-effectiveness completed during an overnight or single-shift closure. The of preservation treatments as part of a project-level treatment results indicated that all of the preservation treatments for selection process. urban PCC roads are considered for overnight or single-shift General ranges in the expected performance of treatments closures. When conventional patching materials are used for applied to HMA-surfaced pavements and PCC roadways are Table 2.7. (continued) Cold Ultra- Thin Thin Milling Thin In-Place Recycling Climatic Bonded HMA and HMA Profile Ultra-Thin Region Course Overlay Overlay Overlay Hot Cold Milling Whitetopping RURAL Deep freeze Moderate Extensive Extensive Limited Limited Moderate Limited Limited Moderate freeze Extensive Extensive Extensive Moderate Limited Moderate Moderate Limited No freeze Moderate Moderate Moderate None None Limited Moderate Limited URBAN Deep freeze Moderate Extensive Extensive Moderate Limited Moderate Limited Limited Moderate freeze Extensive Extensive Extensive Extensive Moderate Limited Extensive Moderate No freeze Moderate Moderate Extensive Limited Limited Moderate Moderate Limited

OCR for page 9
Table 2.8. Preservation Treatment Use on High-Traffic-Volume PCC-Surfaced Roadways, by Climate Region PCC Joint PCC Crack Diamond Diamond Partial-Depth Full-Depth Dowel Bar Thin PCC Thin Bonded Thin HMA Climatic Region Sealing Sealing Grinding Grooving Repair Repair Retrofit Overlay Course Overlay RURAL Deep freeze Moderate Moderate Moderate Limited Extensive Extensive Extensive None Moderate Limited Moderate freeze Extensive Extensive Extensive Moderate Extensive Extensive Moderate Limited Moderate Extensive No freeze Extensive Extensive Extensive Limited Extensive Extensive Moderate Limited Limited Limited URBAN Deep freeze Extensive Moderate Moderate Limited Moderate Extensive Moderate None Limited Limited Moderate freeze Extensive Extensive Extensive Moderate Extensive Extensive Moderate Limited Moderate Moderate No freeze Extensive Extensive Extensive Moderate Extensive Extensive Extensive Limited Moderate Moderate Note: Extensive = Use by 66% of respondents; Moderate = 33% to 66% usage; Limited = <33% usage.

OCR for page 9
11 Table 2.9. Survey Results from Treatments Used During Different Closure Durations for HMA-Surfaced Pavements Rural Urban Overnight or Overnight or Treatment Single Shift Weekend Longer Single Shift Weekend Longer Crack filling Extensive Limited Limited Extensive Limited Limited Crack sealing Extensive Limited Limited Extensive Limited Limited Slurry seal Extensive Limited Limited Extensive Limited Limited Microsurfacing Extensive Limited Limited Extensive Limited Limited Chip seal Extensive Limited Limited Extensive Limited Limited Ultra-thin bonded Extensive Limited Limited Extensive Limited Limited wearing course Thin HMA overlay Extensive Limited Limited Extensive Limited Limited Cold milling and overlay Extensive Limited Limited Extensive Limited Limited Ultra-thin HMA overlay Extensive Limited Limited Extensive Limited Limited Hot in-place HMA recycling Extensive Limited Limited Extensive Limited Limited Cold in-place recycling Extensive Limited Limited Extensive Limited Limited Profile milling Extensive Limited Limited Extensive Moderate Limited Ultra-thin whitetopping Moderate Limited Moderate Moderate Moderate Moderate Note: Extensive = Use by 66% of respondents; Moderate = 33% to 66% usage; Limited = <33% usage. Table 2.10. Survey Results from Treatments Used During Different Closure Durations for PCC-Surfaced Pavements Rural Urban Overnight or Overnight or Treatment Single Shift Weekend Longer Single Shift Weekend Longer Concrete joint resealing Extensive Limited Limited Extensive Limited Limited Concrete crack sealing Extensive Limited Limited Extensive Limited Limited Diamond grinding Extensive Limited Limited Extensive Limited Limited Diamond grooving Extensive Limited Limited Extensive Limited Limited Partial-depth concrete patching Extensive Moderate Moderate Extensive Moderate Limited Full-depth concrete patching Extensive Moderate Moderate Moderate Moderate Moderate Dowel bar retrofitting Extensive Moderate Moderate Moderate Moderate Moderate Ultra-thin bonded wearing course Extensive Limited Limited Extensive Limited Limited Thin HMA overlay Extensive Limited Limited Extensive Limited Limited Note: Extensive = Use by 66% of respondents; Moderate = 33% to 66% usage; Limited = <33% usage.