단기노화 수준이 아스팔트 콘크리트의 수분저항성에 미치는 영향

PURPOSES: The objective of this study was to investigate the effect of short-term aging level on the moisture resistance of a dense-graded asphalt mixture by measuring its deformation strength ratio (SDR). METHODS : Three short-term aging (STA) durations (1, 2, and 4 h) at two different temperatures (160℃ and 180℃) were used for the normal dense-graded hot-mix asphalt (HMA) mixtures prepared using PG 64-22 asphalt and 13mm aggregate with and without hydrated lime (HL). The specimens were prepared using a gyratory compactor, after each STA, to achieve a WC-1 gradation as defined by the Korean guide. The SDR was measured after freezing-and-thawing (F-T) conditioning, and submerging the specimen into water at 60℃ for 72 h. RESULTS: The results indicated that the moisture resistance decreased with the increase in STA duration. After STA at 160℃ and 180℃, the SDR values, measured after F-T treatment, or after submerging into 60℃ water for 72 h, decreased with the increase in STA duration. However, when HL was used in the same asphalt mixtures, the SDR improved, for identical STA conditions. Therefore, the moisture resistance of the asphalt mixture was affected by the short-term aging duration, and decreased with the increase in aging duration. However, HL effectively retarded aging, and the moisture resistance, as indicated by the SDR, improved in the HL-added mixes, which had aged lesser than the normal mixes. CONCLUSIONS : It was concluded that the moisture resistance of the asphalt mixture decreased with the increase in aging level, and hydrated lime was effective in preventing the degradation of the moisture resistance by reducing the age-hardening of the binder. However, since this study used a limited range of materials, further studies using more materials are required to reach a more generalized conclusion.