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原文传递 Low Temperature and Moisture Susceptibility of RAP Mixtures with Warm Mix Technology.

题名：	Low Temperature and Moisture Susceptibility of RAP Mixtures with Warm Mix Technology.
作者：	Mogawer, W. S.
关键词：	Low temperature alloys, Moisture Susceptibility, Hot mix asphalt (HMA) mistures, Recyclable materials, Reclaimed asphalt pavement (RAP)
摘要：	The increasing price of asphalt binder has led to a continuous trend of increase in the price of Hot Mix Asphalt (HMA). Correspondingly, the HMA industry has been searching for methods to decrease cost of materials without compromising performance. One such method is to use more of readily available recyclable materials like Reclaimed Asphalt Pavement (RAP). RAP has been used successfully in surface HMA mixtures since the 1970’s at percentages generally around 20%. The concern associated with the use of higher RAP contents is that the resultant mixture might be unworkable and too stiff. Consequently, such mixtures might be prone to failures in the field (1,2,3). The aged binder in the RAP is what leads to the mixture being too stiff. Accordingly, research and specifications have suggested/recommended the use of a softer virgin binder than would typically be used for the same mixture when no or low RAP is incorporated. The performance of mixtures with RAP will depend heavily on the degree of blending between the softer virgin binder and the RAP binder. If no blending between the virgin and the RAP binders occur, the mixture can be susceptible to rutting due the softer virgin binder used. Furthermore, if a low degree or no blending occurs, the resultant mixture will contain less than targeted binder content which could lead to mixtures prone to cracking such as thermal cracking. Factors that might affect the degree of blending between the aged and virgin asphalt binders are: plant type, production temperature, mixing time, discharge temperature, RAP source, and RAP properties. Several laboratory research studies have been done to measure the degree of blending between the aged and virgin binder. These studies illustrated that there is a degree of blending between RAP binder and virgin binder by measuring the dynamic modulus of the mixtures and the complex modulus of the extracted binder (1, 2). Recently, new technologies have been introduced that may help improve the workability and performance of mixtures incorporating larger amounts of RAP and concurrently make them more environmentally friendly. These technologies, known as Warm Mix Asphalt (WMA) technologies, permit production and placement of HMA mixtures at lower temperatures than conventional mixtures. These temperature reductions allow for the fabrication of more environmentally friendly mixtures since plant and field emissions are reduced. The lower production temperatures may also decrease the amount of mixture aging thereby decreasing the mixture stiffness. This may lead to a mixture less prone to cracking.
报告类型：	科技报告