PURPOSES : A mechanistic-empirical (ME) predictive design logic that can compute the reflective cracking life of hot-mix asphalt (HMA) overlaid on top of a composite pavement is proposed herein.
METHODS : The overlay thickness design and analysis logic of the HMA were formulated based on the ME concept of reflection crack propagation. Climate data, traffic load data, the pavement material properties, and the thickness of each layer of the pavement are the main inputs for the ME-Reflective Cracking Rate (RCR) prediction algorithm. An Microsoft Excel Virtual Basic for Application (VBA) program was created to aid designers in assessing the expected performance of an HMA overlay design. Calibration was done using data from the Long-Term Pavement Performance (LTPP) sections. Sensitivity analysis was conducted to compare the results yielded by the program and data from a report by the Texas Transportation Institute.
RESULTS : The predictive model performance effectively generates the dynamic and relaxation modulus curves. The correlation value of the calibration factors, R2, is 0.79. The calibration factors used for the Asphalt Overlay Thickness Design (AOTD) program and the sensitivity analysis, i.e., k1, k2,, and k3,, are set to 5, 5, and 150, respectively. The sensitivity of the AOTD program affords reasonable results. Additionally, the program yields results similar to the trends presented in a report by the Federal Highway Administration.
CONCLUSIONS : The proposed ME design logic is successfully translated into an Excel VBA program, AOTD, which can perform routine assessments of laboratory tests for HMA overlays. The program can effectively perform numerous iterations and computations to predict an HMA overlay. The predictive model can generate reasonable dynamic modulus and relaxation modulus curves for the characterization of HMA overlays. Under the same asphalt binder grade and HMA type, doubling the HMA overlay thickness yields three times the expected reflective cracking service life.

ABSTRACT
1. Introductuon
    1.1. Objectives
2. Methods
    2.1. Mechanistic-Empirical Design Logic Algorithm
    2.2. Reflective Cracking Model
    2.3. LTE-based Calibration
    2.4. Sensitivity Analysis
3. Results-discussion
    3.1. Predictive model performance
    3.2. General calibration
    3.3. Sensitivity analysis
4. Conclusions
REFERENCES

• Kim Je-Won(한국건설기술연구원 도로교통연구본부 수석연구원) | 김제원
• Aplicano Bruce Alfred(군산대학교 공과대학 토목공학과 연구원) | 아플리카노브루스
• Andryant Debby Marcelia(안드리얀티데비)
• Park Dae-Wook(군산대학교 공과대학 토목공학과 교수) | 박대욱 Corresponding author