PURPOSES : The aim of this study is to evaluate the effects of air voids, binder content, and aggregate gradation on the indirect tensile strength (IDT) and cracking tolerance index (CTindex) of cored asphalt pavements.
METHODS : Cored samples were obtained from roads in Incheon city, and several laboratory experiments were performed. First, the cored samples were first to cut into a size appropriate for the IDT test. Subsequently, the air voids of the samples were measured. The damaged sample from the IDT test was loose mixed at 150 ℃ before the binder content was determined, which was conducted via an asphalt extraction test. Finally, the clean aggregates obtained from asphalt extraction process were analyzed in the aggregate gradation test.
RESULTS : The result shows that an increase in air voids from 4% to 8% decreases the IDT and cracking tolerance index (CTindex) by 30% and 28%, respectively. Incorporating a binder enhances the ductile behavior of the asphalt mixture, resulting in a higher CTindex. Finally, the contribution of the aggregate grade on the IDT and CTindex is negligible.
CONCLUSIONS : The IDT and CTindex are primarily affected by the air voids and binder content. A higher percentage of air voids results in a lower IDT. In addition, a higher amount of binder increases the IDT and CTindex of the cored samples. Meanwhile, the aggregate grade does not affect the IDT.

ABSTRACT
1. Introductuon
    1.1. Literature review
    1.2. Research contents
2. Test method
    2.1 Sample collection and preparation
    2.2. Air void test
    2.3. Indirect tensile strength test
    2.4. Indirect tensile asphalt cracking test (IDEAL-CT)
    2.5. Measurement of asphalt binder content
    2.6. Aggregate gradation test
3. Results-discussion
    3.1. Effect of air void
    3.2. Effect of binder content
    3.3. Effect of aggregate gradation
4. Conclusions
REFERENCES

• Lee Su-Hyung(한국건설기술연구원 도로교통연구본부 수석연구원) | 이수형
• Phan Minh Tam(군산대학교 공과대학 토목환경공학과 석사과정생) | 반민담
• Lam My Phung(군산대학교 공과대학 토목환경공학과 박사과정생) | 람미풍
• Park Dae-Wook(군산대학교 공과대학 토목공학과 교수) | 박대욱 Corresponding author