Research Problem Statement: AASHTO has adopted the pavement rehabilitation design procedures developed under the NCHRP 1-37A project for flexible and rigid pavement structures. These new procedures are based on mechanistic-empirical principles and they replace the earlier empirical procedures. The new procedures are incorporated in the AASHTOWare Pavement ME Design software. A revised version of the procedures, based on the reflection cracking models developed under NCHRP 1-41 project, will be incorporated in the software soon. The asphalt concrete (AC) rrehabilitation procedure consists of AC over PCC overlay, AC over Fractured Slab overlay, and AC over AC overlay. The PCC rehabilitation design consists of overlay analysis and restoration analysis. The overlay analysis is applicable to the flexible/composite and rigid pavements whereas restoration is for rigid pavements only. The most pronounced changes are detailed data required for higher hierarchical levels of overlay design and the life-cycle cost (LCC) analysis. However, the proposed procedures are very sound and flexible and they considerably surpass any currently available pavement rehabilitation analysis tools including the 1993 AASHTO design guide. It is expected that Kansas DOT and other state agencies will adopt these procedures to replace the methodologies in Chapter 5 of the 1993 AASHTO design guide currently in use. To ensure a more efficient rehabilitation design it is imperative to conduct the local calibration of the design procedures and to determine the material inputs for the rehabilitation materials used in local States.

The objective of this research project is to facilitate the implementation of the AASHTO design guide procedures for rehabilitation design of existing flexible, composite, and rigid pavement structures for the local condition. The project will primarily assist the state DOTs pavement design personnel in implementation of the new Guide for the overlay design and LCC analysis.

It is envisioned that this study will be accomplished through the following tasks: 1. Literature Search - Tier 1-2: A literature search will be conducted to gather detailed information on the AASHTO MEPDG Guide and AASHTOWare Pavement ME software for rehabilitation design procedures, input requirements, SPS-5 and SPS-6 information available in Kansas and other participating states, etc. 2. Pavement Rehabilitation Strategy Performance – Tier 1: At this stage of the project, a database with the required inputs for all levels of hierarchy will be developed. The task will collect performance information from past typical rehabilitation projects in each participating state for both rehabilitated flexible and rigid pavements. The data will be useful for life-cycle cost analysis of different rehabilitation strategies. The format of data that each participating state will need to submit to Kansas State University is Microsoft Access database format or MS SQL Server. Tier 2: If a state cannot submit data in the format required, an addition fee will be required to get the data in the right format. The fee will depend on the quality and quantity of data available from that state. 3. Material Input Database – Tier 1: Under this task the material inputs required by the new design procedures will be determined in the laboratory for typical rehabilitation materials used in each State. They will include conventional hot-mix asphalt (HMA), WMA and recycled asphalt mixes. Each participating state will be required to send their materials to Kansas State University. 4. Calibration of Distress Models and LCC Analysis- Tier 1: In this task, rehabilitation design runs will be made for overlay design of both flexible and rigid pavements for rehabilitation projects in each State. The comparison between the predicted distresses by the new design procedures and the field measured distresses will be used to calibrate the distress models. Concurrent overlay designs will also be made using the 1993 AASHTO design guide Chapter 5 procedures, and compared with the original design. It is to be noted that the Level I analysis is heavily dependent upon the backcalculated asphalt concrete/PCC moduli from the non-destructive test (for example, FWD for KDOT) data. Thus the backcalculation process and the most suitable software will also be evaluated. LCC analysis for different scenarios will also be done. 5. Investigation of GPR Usage on Rehabilitation Projects- Tier 1(optional): Ground Penetration Radar (GPR) survey of existing pavement has been highly recommended by the new Guide to identify distressed existing AC layer such as those with stripping. This is especially applicable to Kansas since a large number of projects in Kansas are known to have been built up over the years and known to have stripped or weakened material (e.g. CIPR) layers. Kansas State University (KSU) has an SIR-3000 GPR from Geophysical Survey Systems, Inc. (GSSI). The SIR-3000 is equipped with a display screen and signal processing for real-time imaging and is interchangeable will all GSSI antennas from 16 to 2600 MHz. KSU currently has two antennas with depths of penetration from 0 - 9 m (0 - 30 ft) and 0 - 4 m (0 - 12 ft). The 0 – 4 m antenna (400 MHz) is well suited for imaging rehabilitated pavements. A 900 MHz antenna with penetration to 1 m (3 ft) can be used if more detailed images of the upper layers of the pavements are deemed necessary. 6. Reporting and Training – Tier 1-2: A final report will be prepared that will give detailed information on methodology and data used for the AASHTO MEPDG Guide and AASHTOWare Pavement ME software implementation for rehabilitation design. The report will include recommendations on the optimum use of the AASHTO Guide and life cycle cost analysis methodology as well as recommended default input values for the required parameters. Training of the state pavement design personnel will be con

Kansas DOT is looking for a minimum of two other states to participate in Tier 1 tasks 1-6 excluding task 5 for a cost of $35,000 per year for 3 years. Task 5 Tier 1 can be completed for an additional cost of $10,000 per participating state. Costs for Task 2, Tier 2 will need to be coordinated on an individual state basis with the project’s investigator. This will be negotiated after the project is awarded.