Performance-Related Specifications for Pavement Preservation Treatments (2017) / Chapter Skim
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60 C h a p t e r 6 6.1 Introduction This chapter presents examples to illustrate use of the PRS guidelines developed in Chapter 5. The examples use field data to develop AQC and performance relationships for chip seal and diamond grinding.
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examples 61 by the application of rolled aggregate chips. Generally, chip seals are applied to seal longitudinal, transverse, and block cracking; inhibit and retard raveling/weathering; improve friction; improve ride quality; and inhibit moisture infiltration.
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62 performance-related Specifications for pavement preservation treatments The PEM and P2EM values represent the bleeding and aggregate loss failure criteria, respectively, with regard to the gradation. The PEM value is defined as the percentage passing that corresponds to 70% of the median particle size on the gradation curve.
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examples 63 aggregate embedment depth, which is directly related to bleeding performance of chip seals. Lower MPD values increase the likelihood of bleeding and skid-resistance problems.
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64 performance-related Specifications for pavement preservation treatments as an AQC for the bond strength between the aggregate and emulsion used in a chip seal and as an indicator of the chip seal's resistance to aggregate loss. This research also showed that the Vialit aggregate loss test differentiates between modified and unmodified emulsions at different temperatures.
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examples 65 perform better than less uniform gradations in terms of aggregate loss and bleeding failure criteria (Adams and Kim 2011, Lee and Kim 2009)
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66 performance-related Specifications for pavement preservation treatments Figure 6-4. Approach for developing threshold values for the PUC based on design rates.
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examples 67 bleeding after 1 year in service. For chip seal sections with AADT between 1,000 and 4,500 vehicles, sections with a 1-week MPD below 2.12 mm exhibited bleeding within 1 year of service but sections with a 1-week MPD above 2.12 mm did not exhibit bleeding.
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68 performance-related Specifications for pavement preservation treatments and the PUC demonstrates the ability to predict the key performance measures associated with chip seal treatments.
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examples 69 5. Specify Test Methods to Measure AQC The following section describes the test methods to measure different AQCs.
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70 performance-related Specifications for pavement preservation treatments repair or replace the chip seal at no cost to the agency. This requirement minimizes the risk to the agency by ensuring that bleeding does not occur within the agreed-upon warranty period while also avoiding penalizing the contractor unless significant bleeding can be validated instead of relying on a predictive indicator of bleeding.
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examples 71 6. Establish a Sampling and Measurement Plan As noted previously, the risks associated with incorrectly accepting or rejecting a lot are related to sample size and method.
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72 performance-related Specifications for pavement preservation treatments 4. Select the appropriate verification sampling frequency.
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examples 73 Also, the survey respondents unanimously recommended that the contracted party also should be responsible for addressing any vehicle damage claims at no cost to the state highway agency. Mean Profile Depth (MPD)
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74 performance-related Specifications for pavement preservation treatments • The PWLs calculated for each AQC can be used to determine if a lot will receive full pay (AQC>90) , partial pay (60 |
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examples 75 3. Establish AQC-Performance Relationships and Determine Performance Limits To validate relationships between the AQC and pavement performance, it was necessary to evaluate the performance of the pavement sections that were diamond ground.
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Figure 6-11. Change in IRI versus change in DLI before and after grinding.
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examples 77 • When diamond grinding reduced the surface roughness, it generally reduced the dynamic loads. The few sections that showed higher roughness after grinding exhibited a minimal change in dynamic loads or in some cases (Section 27-3009)
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78 performance-related Specifications for pavement preservation treatments Figure 6-14. Predicted performance for pavement Section 42-3044.
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examples 79 Figure 6-15. Predicted performance for pavement Section 27-3009.
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80 performance-related Specifications for pavement preservation treatments to determine the SLE for each grinding treatment. The SLE was estimated by subtracting the before grinding "time-to-threshold" from after grinding "time-to-threshold" in years.
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examples 81 (a)
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82 performance-related Specifications for pavement preservation treatments 2. Set specification limits.
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examples 83 • The DPWL value that can be used as the AQL can be obtained as shown in the example. • The DPWL value that can be used as the RQL can be obtained as shown in the example.
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84 performance-related Specifications for pavement preservation treatments within a lot. Although the risks associated with sampling will depend on sample size, the profile signal analysis showed poor sensitivity to the DLI (which was designed to capture the dynamic load of truck traffic)
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examples 85 The PWL value of a lot is calculated using the quality index (Q value) of the specification limits.
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86 performance-related Specifications for pavement preservation treatments is not only acceptable but exceeds the desired quality. Similarly, a measured roughness greater than 90 inch/mile should not be rejected if the roughness level does not substantially exceed the target quality, but it would not deserve full pay.
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examples 87 Figure 6-22. DPWL due to grinding versus predicted SLE for different performance measures.
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88 performance-related Specifications for pavement preservation treatments change in quality ranging from 0 to 100 DPWL because SLE is a function of DPWL [see Equations 6-4 through 6-6]
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examples 89 Table 6-8. Summary of pay factor for cracking.
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90 performance-related Specifications for pavement preservation treatments of DPWL = 55 will be accepted, but will receive reduced pay or a disincentive. This logic can be similarly applied to the EP models for faulting and IRI (see Table 6-11)
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examples 91 (a) Fatigue cracking (b)
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92 performance-related Specifications for pavement preservation treatments Figure 6-24. Predicted cracking OC curves.
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examples 93 As mentioned before, an agency can set the sample size based on their resources and balancing the risk. Similar logic can be applied when evaluating the risks associated with receiving the appropriate pay factor for predicted faulting and roughness, shown in Figures 6-25 and 6-26, respectively.
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