PURPOSES: The purpose of this study is to evaluate the mechanical properties of a cold-recycling asphalt mixture used as a base layer and to determine the optimum emulsified-asphalt content for ensuring the mixture’s performance.
METHODS: The physical properties (storage stability, mixability, and workability) of three types of asphalt emulsion (CMS-1h, CSS-1h, and CSS-1hp) were evaluated using the rotational viscosity test. Asphalt emulsion residues, prepared according to the ASTM D 7497-09 standard, were evaluated for their rheological properties, including the G*/sinδand the dynamic shear modulus (|G*|). In addition, the Marshall stability, indirect tensile strength, and tensile-strength ratio (TSR) were evaluated for the cold-recycling asphalt mixtures fabricated according to the type and contents of the emulsified asphalt.
RESULTS: The CSS-1hp was found to be superior to the other two types in terms of storage stability, mixability, and workability, and its G*/sinδ value at high temperatures was higher than that of the other two types. From the dynamic shear modulus test, the CSS-1hp was also found to be superior to the other two types, with respect to low-temperature cracking and rutting resistance. The mixture test indicated that the indirect tensile strength and TSR increased with the increasing emulsified-asphalt content. However, the mixtures with one-percent emulsified-asphalt content did not meet the national specification in terms of the aggregate coverage (over 50%) and the indirect tensile strength (more than 0.4 MPa).
CONCLUSIONS : The emulsified-asphalt performance varied greatly, depending on the type of base material and modifying additives; therefore, it is considered that this will have a great effect on the performance of the cold-recycling asphalt pavement. As the emulsified-asphalt content increased, the strength change was significant. Therefore, it is desirable to apply the strength properties as a factor for determining the optimum emulsified-asphalt content in the mix design. The 1% emulsified-asphalt content did not satisfy the strength and aggregate coverage criteria suggested by national standards. Therefore, the minimum emulsified-asphalt content should be specified to secure the performance.

ABSTRACT
 1. 서론
 2. 국내외 동향 조사
 3. 유화아스팔트 특성 분석
  3.1. 유화아스팔트의 기본물성
  3.2. 유화아스팔트의 실내 역학특성 분석
 4. 실내실험
  4.1. 상온 재활용 아스팔트 혼합물의 배합설계
  4.2. 유화아스팔트 함량별 혼합물 제조
  4.3. 마샬안정도 및 간접인장강도 실험결과
  4.4. 수분민감도 평가
 5. 결론
 REFERENCES

• 양성린(한국건설기술연구원 미래전략실·공학석사) | Yang, Sung Lin
• 손정탄(한국건설기술연구원 도로연구소·공학석사) | Son, Jung Tan
• 이강훈(한국건설기술연구원 도로연구소·공학석사) | Lee, Kang Hun 교신저자