Incorporation of Joint Faulting Model into BCOA-ME
Status: Completed June 30, 2021
Faulting of joints has been observed to be a common distress in Bonded Concrete Overlays on Asphalt (BCOA). However, faulting is not considered in any of the current design procedures for BCOA. Faulting is caused by pumping forces which remove supporting materials either at the bottom of the overlay slab within the asphalt layer or below the asphalt in the granular layer. This location is dictated by the depth of joint propagation. Current faulting design procedures, such as those incorporated into Pavement ME, were developed considering only jointed plain concrete pavements (JPCP). It is possible to use the current design software to predict joint faulting for full-lane width BCOAs, but it is calibrated with JPCP faulting data. JPCPs are typically thicker than BCOAs and have longer panel lengths. There are also a number of equivalency concepts employed in the Pavement ME to simplify the analysis, including equivalent thickness, equivalent temperature gradient, and equivalent slab that are not appropriate for BCOAs.
Work is underway at the University of Pittsburgh to incorporate a faulting model into the BCOA-ME design procedure. That work is being funded by PennDOT and focuses on the impact of the climate in Pennsylvania. To adopt this for NRRA member states, a significantly larger range of climatic conditions must be consider. The proposed work will be performed so that the faulting model developed under the PennDOT project can be expanded to include climate stations in NRRA member states.
This project will expand the climate stations being incorporated into the new faulting model for the BCOA-ME design procedure. It will perform Enhanced Integrated Climatic Model (EICM) analyses for the conditions defined in the experiment to determine the temporal temperature profiles in the overlay and the mid-depth asphalt temperature. A database will be then populated with calculated parameters and their respective pavement structure and geographical information. Equations will be developed so that an equivalent effective linear temperature gradient and an effective asphalt temperature can be predicted based on the pavement structure and the geographical location. A validation process will be performed to ensure the trends of the predictions are accurate. Finally, implementation will consist of programming the prediction equations into the BCOA-ME web application such that they are able to interact with the faulting model. The validity of the program will then be checked by performing a sensitivity analysis and comparing observed performance with that of the predicted performance for various climatic conditions in NRRA member states.
Task 1: Develop and populate database
Determine which pavement design features and weather stations outside of Pennsylvania will be included in improved BCOA-ME design procedure. Perform EICM analyses for the conditions defined in the step above to determine the temporal temperature profiles in the overlay and the mid-depth asphalt temperature. Determine the equivalent linear gradients for each temperature profile based on equivalent strain. Establish an effective equivalent linear temperature gradient and an effective mid-depth asphalt temperature using the calibrated faulting model. Populate a database with these two calculated parameters and their respective pavement structure and geographical information.
- Scheduled date for task final approval: February 28, 2021
- Deliverable: Task 1 Memo (doc), 2/25/2021
A memorandum summarizing the climate stations chosen, the results of the EICM analysis, and the resulting database.
Task 2: Develop and validate predictive equations
Develop predictive equations so that an equivalent effective linear temperature gradient and an effective asphalt temperature can be predicted based on the pavement structure and the geographical location. A validation process will be performed to ensure the trends of the predictions are accurate.
- Scheduled date for task final approval: April 20, 2021
- Deliverable: Task 2 memo (pdf), 6/29/2021
A memorandum summarizing the predictive equations developed, and the results of the validation process.
Task 3: Implement improved faulting model into BCOA-ME procedure
Implementation will consist of programming the new prediction equations into the web-based BCOA-ME application, such that they are able to interact with the faulting model. The validity of the program will then be checked by performing a sensitivity analysis and comparing observed performance with that of performance predicted for climatic conditions in NRRA member states. Revise user’s documents to reflect update of faulting model.
- Scheduled date for task final approval: June 30, 2021
- Deliverable: Task 3 memo (pdf), 6/29/2021; Revised BCOA Design Procedure from UPitt
A memorandum summarizing the updates to the BCOA-ME procedure, the results of the sensitivity analysis, and comparison of predicted and observed performance. Revised user’s manual and supporting documentation will be posted on BCOA-ME web page.
Principal Investigator: Julie Vandenbossche, University of Pittsburgh
Technical Liaison: John Donahue, MODOT
- NRRA Newsletter Article, November 2018
- Meeting Minutes July 2019 (doc)