Experimental characterisation of base asphalt binder used for shingles production under static and dynamic loading

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Significant fluctuations in asphalt binder cost and limited budget for road construction, as well as growing needs for saving natural resources, have contributed to the increased use of recyclable materials in asphalt pavement industries. During the past decades, many transportation agencies in the USA have investigated the effect of adding different types of recycled asphalt shingle (RAS) on the asphalt mixtures performance, while limits were proposed on the maximum amount of RAS that can be recycled. However, not many studies in the USA and Europe have addressed the possibility of directly using base roofing shingles binders for preparing asphalt mixture despite this binder is relatively less expensive than conventional asphalt binders. In this paper, the mechanical performance of base asphalt binder used for roofing flux and shingle production was evaluated with two experimental test methods: bending beam rheometer creep test and dynamic shear rheometer complex modulus test. Based on experimental data, creep stiffness, m-value, thermal stress, critical cracking temperature and complex modulus were calculated and then compared graphically and statistically with the same parameters obtained from two conventional binders commonly used for asphalt pavements. The comparison between the three binders indicates that the shingle binder presents reasonable low and high temperature performance even though the base binder may have different consistency and performance grade compared to the conventional ones. The statistical analysis suggests that the base binder for shingle production can be successfully incorporated into asphalt mixture and that any current specification limiting the content of shingles binder in asphalt mixture should be more asphalt binder type and mix design specific.