Abstract
Using recyclable materials in asphalt pavement is a fundamental design approach not only for limiting the environmental impact of the construction industry, but also for reducing the overall costs of the road infrastructures. Over the past years, road agencies have developed different policies to incorporate various types of recyclable material into conventional asphalt mixtures. reclaimed asphalt pavement (RAP) is one of the most highly recycled construction materials. However, the aged RAP binder and its stiffer and brittle characteristics compared to the fresh binder may negatively affect the performance of the recycled mixture, especially when operating in cold climates. In this study, the low-temperature response of asphalt mixture prepared with single-recycled RAP (SRRAP) and double-recycled RAP (DRRAP), prepared in the laboratory, is experimentally investigated based on creep testing performed with the bending beam rheometer (BBR). Then, the data were analyzed based on three simple mathematical models to extract information on material behavior. Finally, a new indicator named thermal stress factor (TFS) on low-temperature response is proposed. Relatively poorer performance was observed from SRRAP mixture compared to the asphalt mixture prepared with virgin material. However, the low-temperature response between SRRAP and DRRAP did not present significant differences. The values of TFS support the experimental results and suggest the possibility of considering re-recycling technology for further research with the objective of a possible application in the asphalt pavement industry.
Highlights
In the asphalt pavement industry, recyclable materials such as reclaimed asphalt pavement (RAP), end of life asphalt shingles, construction and demolition waste, steel slag, waste rubber and waste tire have been widely considered for pavement construction over the years [1,2,3,4,5,6,7,8,9,10,11,12,13]
Two main advantages can be identified from the use of RAP: first, approximately 0.8–1.1% of the asphalt binder amount can be saved during the mixture production when incorporated with virgin material [1,2,3,4,5,6,7,8,16] compared to the conventional asphalt mixtures and second, due to the incorporation of RAP in the mix design, aged pavement layers can be reused mitigating the overall environmental impact of the construction process [11,12,13,14]
A total of five different asphalt mixtures were prepared with an asphalt binder commonly used in South Korea presenting a performance grade PG 64–22 [34]
Summary
In the asphalt pavement industry, recyclable materials such as reclaimed asphalt pavement (RAP), end of life asphalt shingles, construction and demolition waste, steel slag, waste rubber and waste tire have been widely considered for pavement construction over the years [1,2,3,4,5,6,7,8,9,10,11,12,13]. It is well known that RAP mixtures tend to present higher stiffness and potentially increased brittleness compared to conventional hot mix asphalt (HMA) mixtures This may imply relatively better performance against rutting; potentially poorer resistance to fatigue and thermal cracking may be expected [1,2,3,4,5,6,7,9,10,14,16]. Hunger and Kawakami [27] experimentally addressed various properties of DRRAP mixtures, including moisture sensitivity, resistance to deformation and fatigue behavior They concluded that up to 40% of recycled material can be incorporated in the design of double-recycled mixtures to be used in the pavement without any significant performance deterioration compared to the conventional HMA. Not many studies consistently addressed the effect of DRRAP on the low-temperature performance both experimentally and through the application of different mathematical approaches for the analysis of the data
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