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Use of PMS Data for Performance Monitoring with Superpave as an Example
7. Specific Requirements for Linking Databases (With Superpave as Example)
7.1. General Requirements
- All data must be available in electronic format in systems with search and filter capabilities. Most PMS databases conform to this requirement, but materials, design, testing, construction and QC/QA data are often stored in flat files.
- The electronic evaluation system, linking the PMS database with the Materials/Construction/QC databases, should be manageable and user friendly, it is recommended that universal software be used so that the output can be easily reported, exchanged and compared;
- Each database should have an "owner" who is responsible for the timely upkeep and the quality of data. These "owners" should work in an organizational structure that facilitates open communications among them.
7.2. Performance Evaluation Data
- The performance evaluation data must be linked to the correct materials and construction data, using a common denominator such as project number and exact mile point (or GPS coordinates). This requires three checks:
- Check the exact location (mile point and lane) of the material in question. This will only be possible when records are kept of the placement of each batch or lot as produced by the hot mix plant;
- Check the exact location of the testing of in-place properties such as density/degree of compaction and thickness.
- Make sure that the location where performance data are collected does indeed correspond with the location of the material being studied.
- Use the appropriate performance indicators for the distress or performance being studied. For Superpave this could mean comparisons of rutting, cracking, and/or ride quality when studying effects of mix or binder type, compaction effort, traffic loadings, temperature, age, types of specifications, etc. Other examples are given in Section 10.
- Make sure that the performance indicators used are properly defined, standardized and consistently applied.
7.3. Environmental and Traffic Data
- Incorporate relevant climate data (temperature, rainfall, etc);
- Check proper drainage;
- Make sure reliable information is used for actual traffic volume and loads.
7.4. Materials Data
- Limit information for materials properties, design and testing to data that is essential to an individual DOT;
- Make proper categorization of (Superpave) mix type, such as coarse or fine, binder type (grade bumping), etc;
- Check whether mix design was done according to specifications and appropriate performance testing.
7.5. Construction and QC/QA Data
- Information is required on total pavement structure, including subgrade, and actual layer thicknesses and strength;
- Check that actual thicknesses conform to the pavement design specifications;
- Check whether as-placed materials properties, including stiffness and degree of compaction conform to specifications.
7.6. Examples for Superpave Mix Performance Monitoring
Examples are given below of data from the PMS, Materials and Construction databases that are relevant for the monitoring of the performance of Superpave:
7.6.1. From PMS Database
- Performance Data, such as ride (IRI, etc), rutting (identify contributing layer), cracking (fatigue, low temperature, reflective, etc), surface deterioration (raveling etc) and skid resistance;
- Location (mile point, lane) and project number;
- Traffic loadings (ESALS) and climate data;
- Age of Superpave pavement.
7.6.2. From Materials Database
- Asphalt/binder test data & PG classification (e.g. PG 64-22);
- Aggregate test data, such as coarse and fine aggregate angularity (CAA, FAA) and gradation (coarse, fine, control points, restricted zone);
- Other (sand equivalent, etc);
- Laboratory mix test data, such as Gyratory test data, volumetric properties, water sensitivity test data and mix performance test data like Hveem "S" value, Marshall test, Rut test, Stiffness (E*, phase angle), creep test, repeated load test, shear test, axial load test, etc.
7.6.3. From Construction and QC/QA Data
- Location, mile point, lane, and project number;
- Asphalt mix composition as placed (grading, binder content and grade);
- Voids content (VIM, VMA, VFA) and degree of compaction;
- Actual layer thicknesses (e.g. from cores, or non destructive testing);
- Other relevant construction information (rain, delays, etc).
7.6.4. Examples of Parameters to Investigate
The four examples given below illustrate how the process of linking the PMS data to the Materials database can be used to evaluate the Superpave mix technology, which includes the binder specification, aggregate requirements, volumetric mix design and accelerated performance tests of mixes if available.
- Low temperature cracking: plot degree of transverse cracking as a function of time for different Superpave binder grades in different climates. These plots, together with an examination of field construction data, may indicate changed aging requirements in MP-1 binder specs;
- Grade bumping: compare rut depth as a function of ESAL's for two grades, e.g. PG 64-22, and a grade bumped to PG 70-22. The latter is expected to show less influence of higher ESAL values.
- Effect of fine aggregate angularity (FAA): check the observed rutting for several levels of increased FAA levels for similar traffic, environment and mix design.
- Effect of aggregate gradation (coarse vs. fine) on roughness: Check roughness levels for three levels of traffic loading for two types of Superpave mixes, one with fine, and the other with coarse aggregate, and make sure that all other conditions are comparable. One would expect the coarse mix to show higher roughness values, this effect might increase with higher ESAL values.
These four examples are illustrated in more detail in Appendix C.
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