Low Temperature Tensile Characteristics of Warm-Mix Asphalt Mixtures

초록

The tensile strength (St) of warm-mix asphalt (WMA) and hot-mix asphalt (HMA) concretes were measured by indirect tensile strength test at 25, 5, -5, -15, -25 and -35 degrees C. Fracture toughness (Tu) was calculated from each of the St test curves. Two WMA additives and two polymer modifiers were used to produce WMA mixtures at 135 degrees C in the laboratory. All asphalt concretes evaluated in this study showed St increase by temperature decreases, peaking at -15 degrees C or -25 degrees C, then decreasing with further lowering of temperatures. The St values of WMA mixtures were observed to be higher than those of HMA mixtures in most cases at all low temperatures evaluated in this study. After being subjected to differential thermal contraction damage at -15 and/or -20 degrees C, most of the WMA mixtures showed higher St than HMA mixes at severely low temperatures (-25 and -35 degrees C). Therefore, it was concluded that the WMA mixtures had stronger St than HMA mixtures at low temperatures when prepared with the same low-temperature PG binders, even though they were produced at a lower aggregate-heating temperature.

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