PURPOSES : In this study, the thermal conductivity properties and mechanical performance of a thermally conductive asphalt mixture that can be applied to increase the efficiency of deicing asphalt pavements are evaluated.
METHODS : Graphite powder and carbon fiber, which are inexpensive carbon materials, were added to the asphalt mixture to its conductivity. To determine the optimal mixing ratio of the carbon materials, the dispersibility, thermal conductivity, and performance of the conductive asphalt mixture were evaluated. The performance of the mixture was evaluated in terms of its volume characteristics, Marshall stability, dynamic modulus, indirect tensile strength (IDT), and wheel-tracking tests.
RESULTS : The thermal conductivity of the asphalt mixture containing 2% graphite is 1.81 W/mK, which is approximately twice (0.94 W/mK) that of a general asphalt mixture. Meanwhile, the graphite-added asphalt mixture indicates a much higher temperature increase rate than the general asphalt mixture, and its surface temperature after 60 min is 7.5 ℃ higher. In addition, it reaches 0 ℃ from -10 ℃ at a rate 1.5 times higher than that required by the general asphalt mixture. When both 2% graphite and 1% carbon fiber are added, the thermal conductivity improves to 2.03 W/mK, and the conductivity is similar at all locations of the slab specimen location, which indicates no dispersibility issue. The results of the mechanical performance evaluation shows that the higher the ratio of the carbon material, the lower is the dynamic modulus and IDT at 20 ℃, which decreases the crack resistance. Meanwhile, the results of the Hamburg wheel-tracking test at 50 ℃ show an improvement in the permanent deformation resistance.
CONCLUSIONS : The results of the conductivity and performance evaluation show that the optimal ratio is the combination of 2% graphite and 0.5% carbon fiber. This suggests that the conductive asphalt mixture incorporated with carbon materials can efficiently transfer heat generated from the heating layer at the bottom of the pavement to the pavement surface.

ABSTRACT
1. 서론
2. 그라파이트 첨가한 아스팔트 혼합물의 전도성평가
    2.1. 재료별 특성
    2.2. 아스팔트 혼합물 시편 형상에 따른 전도성 영향평가
    2.3. 그라파이트 함량에 따른 아스팔트 혼합물의 열전도특성 분석
3. 전도성 아스팔트 혼합물의 성능 평가
    3.1. 그라파이트 및 탄소섬유 혼입 아스팔트 혼합물의열전도 특성 분석
    3.2. 전도성 아스팔트 혼합물의 공용성 평가
4. 결론
REFERENCES

• 백철민(한국건설기술연구원 도로교통연구본부 수석연구원) | Baek Cheolmin Corresponding author