PURPOSES: Using recyclable materials in asphalt pavement industry is one of the essential tasks not only for saving construction budgets but also for mitigating environmental pollutions. Over the past decades, several efforts have been made by road maintenance agencies to incorporate various recyclable materials into virgin asphalt paving mixtures. As a result, reclaimed asphalt pavement (RAP), which consists of old pavement material was selected as one of most widely used recyclable materials. In this paper, the effects of using different amounts of single-recycled RAP (SRRAP) and double-recycled RAP (DRRAP) on the low-temperature characteristics of asphalt mixtures were investigated.
METHODS: To evaluate the low-temperature characteristics of SRRAP and DRRAP mixtures, two experiments, the bending beam mixture creep test and semicircular bending fracture test were performed. The experimental parameters: creep stiffness, m-value, thermal stress, critical cracking temperature, fracture energy, and fracture toughness were computed then compared. RESULTS : RAP mixtures (SRRAP or DRRAP) showed lower mechanical performance compared with conventional asphalt mixtures. The differences became distinct with increased RAP addition. However, the performance differences between SRRAP and DRRAP mixtures were not significant in all cases, which indicate the possible application of re-recycling technology (DRRAP) in the asphalt pavement industry.
CONCLUSIONS : The addition of RAP to virgin asphalt can mitigate low-temperature performance despite the improvement in fracture performance observed in some cases. Therefore, using RAP (SRRAP or DRRAP) mixtures on inter or sublayer construction, but not on the surface layer, is recommended. Moreover, the possibility of applying double-recycling technology in asphalt pavement industry can be introduced in this study because not significant performance differences were found between SRRAP and DRRAP mixtures especially at low temperature.

ABSTRACT
 1. INTRODUCTION
 2. MATERIALS AND TESTING
  2.1. Material preparation (asphalt mixture andcorresponding asphalt binder)
  2.2. Experimental work Part 1: Bending BeamMixture Creep Test (BBMCT)
  2.3. Experimental work Part 2: Semi Circular Bending(SCB) test
 3. DATA COMPARISON METHOD WITH NUMERICALAPPROACH : STATISTICAL METHOD
 4. DATA ANALYSIS
  4.1. Results of low temperature mixture creep testing:Part 1 (visual comparison)
  4.2. Results of low temperature mixture creeptesting: Part 2 (statistical comparison)
 5. SUMMARY AND CONCLUSION
 REFERENCES

• Ki Hoon Moon(Korea Expressway Corporation Pavement Research Division) | 문기호 Corresponding Author
• Oh Sun Kwon(Korea Expressway Corporation Pavement Research Division) | 권오선
• Mun Jin Cho(Do-Kyeong Construction Corporation R&D Center) | 조문진
• Augusto Cannone Falchetto(Technische Universita¨t Braunschweig)