Browsing by Author "Hou, X"

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    item: Conference-Abstract
    Effect of blending temperature and blending duration on the degree of blending of reclaimed asphalt binders
    (Department of Civil Engineering, University of Moratuwa, 2020-12) Hettiarachchi, C; Hou, X; Xiang, Q; Yong, D; Xiao, F; Perera, HLK
    Recycled asphalt mixtures are getting more popular due to many economic and environmental benefits such as a higher degree of recyclability, low material cost, less effect on the environment etc. Typically, reclaimed asphalt pavement (RAP) materials are combined with virgin aggregates and virgin asphalt binder to produce recycled asphalt mixtures. The amount of RAP binder mobilizes into the mixture is called the degree of blending. The degree of blending of reclaimed asphalt pavement (RAP) binder is strongly influencing the performance of recycled asphalt mixtures. If the degree of blending is known, the asphalt mix designers can make better decisions during the mix design process to produce more durable recycled asphalt mixtures. If the degree of blending is overestimated, the mixture could have less amount of binder. On the other hand, underestimating the degree of blending could produce mixtures with higher binder content. Hence, it is very important to properly determine the degree of blending of RAP binder. However, understanding the factors affecting the degree of blending and quantifying the degree of blending is still an open problem for researchers. This study investigates the effect of several factors such as blending method, blending temperature, blending duration, and RAP content on the degree of blending using Fourier Transform Infrared Spectroscopy (FTIR) analysis of the extracted binder from mixtures. It is revealed that the blending method, blending temperature, and blending duration have a significant influence on the degree of blending. The study revealed that prolonged blending durations and elevated mixing temperatures could improve the degree of blending. The amount of RAP in the mixture has little or no influence on the degree of blending. Further, based on the results, a blending chart is developed to determine the degree of blending with regard to blending duration and blending temperature.
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    item: Conference-Abstract
    A Performance review of warm mix asphalt containing reclaimed asphalt pavement materials
    (2019) Hettiarachchi, C; Xiao, F; Hou, X
    The performance of warm mix asphalt (WMA) mixtures containing reclaimed asphalt pavement (RAP) materials has been studied extensively in both laboratory scale experiments and field experiments. Warm mix asphalt technology is using additives or water foaming mechanism to reduce the production and mixing temperatures of asphalt mixtures. At present, there are three main WMA technologies to produce asphalt mixtures: organic additives, chemical additives and foaming technology. The WMA technology is gaining popularity due to its economic and environmental benefits. The reduced temperatures allow WMA mixtures to incorporate high amount of RAP materials making the mixtures more economical. Nevertheless, incorporation of RAP has its own advantages and disadvantages. The performance of WMA mixtures containing RAP is one of the main concerns in the industry. Over the past decade, many studies have been conducted to investigate the performance of WMA mixtures containing RAP. However, many inconsistencies can be found in the literature regarding the performance characteristics of WMA containing RAP due to the availability of numerous warm mix asphalt technologies, inconsistency in RAP materials, use of various percentages of RAP, adhering to different testing methods to evaluate the performance etc. Hence, it is important to investigate the performance of different WMA technologies separately to properly understand the performance of WMA mixtures with RAP. This study presents an extensive and systematic analysis of the available literature regarding WMA and RAP mixtures to properly understand the behavior of RAP mixtures with different WMA technologies. The analysis concludes that the use of RAP in WMA could improve the overall performance in terms of rutting, moisture resistance and workability. However, fatigue performance is only improved in WMA with organic additives while further studies are recommended to evaluate the low temperature performance.