저온하에서 시차열 수축에 의한 WMA 콘크리트의 휨강도 변화 Variation of Flexural Strength of Warm-mix Asphalt Concretes Due to Differential Thermal Contraction at Low Temperatures
pp.63-72
PURPOSES : Hot-mix asphalt(HMA) concretes show a trend of strength increase at low temperature due to binder stiffness increase, but strength decrease below a ceratin low temperature. This is due to the differential thermal contraction(DTC) which is induced by a significant difference in coefficients of thermal contraction between aggregate and asphalt which is coated around the aggregate. This DTC damage is well known to occur in HMA concrete, but is not yet investigated in warm-mix asphalt(WMA) concretes. METHODS : To evaluate DTC damage on WMA in this study, the flexural strength(Sf) of WMA concretes, which were produced at 30~40℃ lower temperature, was evaluated in comparison with that of HMA at -5, -15 and -25℃. RESULTS : Most of WMA and HMA mixtures showed flexural strength increase down to -15℃ and decrease below -15℃. this type of strength reduction below -15℃ can e explained as the effect of differential thermal contraction that is a consequence of the large difference in coefficients of thermal contraction between aggregate and asphalt. the property reduction of WMA is similar the result of previous works dealt with HMA mixtures. CONCLUSIONS : Even though there is some differences by materials used, the WMA concretes showed a significantly lower DTC damage than HMA concrete at low temperature at α=0.05 level.