PURPOSES : The purpose of this study is to evaluate the performance of an ultra-thin asphalt pavement as a preventive maintenance approach through laboratory tests.
METHODS : An ultra-thin asphalt pavement of 2 cm wearing course thickness comprising modified asphalt and aggregate is a preventive maintenance method used for asphalt pavements. A mix design was carried out to determine the optimum aggregate gradation and asphalt contents. A dynamic immersion test was performed to evaluate the water-resistance of the ultra-thin asphalt pavement. A wet track abrasion test and a cohesion test were conducted to examine the applicability of the ultra-thin asphalt pavement in surface treatment. The performance of the ultra-thin asphalt pavement was evaluated through wheel loading tests, such as Hamburg wheel-tracking and third-scale model mobileloading simulator (MMLS-3).
RESULTS : An optimum binder content of 4.9% was obtained in the ultra-thin asphalt mixture from the Marshall mix design. The waterresistance tests indicated a 70% dynamic immersion coverage rate of the ultra-thin asphalt pavement. The wet track abrasion test showed an abrasion rate of 0.0107 g/cm2, and the cohesion tests indicated a 19.0 kg·cm average cohesion at 30 min of operating time and 21.4 kg·cm average cohesion at 60 min of operating time. From the Hamburg wheel-tracking test, a 16.56 mm rut depth at 20,000 wheel passing was obtained. Finally, a 5.87 mm rut depth at 300,000 number of wheel passing was detected from the MMLS-3 test.
CONCLUSIONS : The water-resistance of the ultra-thin asphalt pavement satisfied the recommended guidelines of the Korean Ministry of Land, Infrastructure and Transport. In addition, the applicability of the ultra-thin asphalt pavement as a surface treatment met the standard of the International Slurry Surfacing Association. Furthermore, the deformation performance of the ultra-thin asphalt pavement was 1.5 times better than that of the straight asphalt pavement, based on the results of the wheel-loading tests. Hence, it is estimated that an ultra-thin asphalt pavement has a high performance in the preventive maintenance of asphalt pavement, even though the cracking resistance was not evaluated in this study.

ABSTRACT
1. 서론
2. 재료 및 배합설계
    2.1. 개질재
    2.2. 개질 아스팔트 바인더
    2.3. 골재 입도
    2.4. 배합설계
3. 실내 실험
    3.1. 동적수침 시험
    3.2. 습윤 마모 시험
    3.3. 점착력 시험
    3.4. 함부르크 휠트랙킹 시험
    3.5. 소형 포장 가속 시험(MMLS-3)
4. 결론
REFERENCES

• 김부일(한국건설기술연구원 인프라안전연구본부) | Kim Booil (Research Fellow Korea Institute of Civil Engineering and Building Technology) 교신저자