Investigating the Multi-Recyclability of Recycled Plastic-Modified Asphalt Mixtures

Abstract

Although the benefits of asphalt recycling have been scientifically proven and several best practices are being implemented, further research is required in specific and specialized areas. One of these circumstances is the recycling of Reclaimed Asphalt Pavements (RAPs) that contain asphalt modifiers such as elastomers and/or plastomers. Following the principles of the circular economy and considering the sustainability implications of asphalt mixtures, this paper deals with the multi-recyclability of asphalt mixtures containing 50% RAP with and without a recycled plastic asphalt modifier and rejuvenating agent. The recycled plastic asphalt modifier was made of hard recycled plastics and was introduced to the mixture via a dry method. The research focuses on the characterization of binders via conventional, rheological, and chemical analysis. To control the consistency and variables of the mixtures, the RAP was produced artificially in the laboratory following an ageing protocol for loose asphalt mixtures. According to the obtained results, at all three cycles of binder recycling, comparable properties for (i) the extracted binders from the recycled plastic-modified asphalt mixture, (ii) the extracted binders from the control un-modified mixture, and (iii) the reference bitumen 50/70 were obtained. This was even noticed when a nearly similar quantity of the rejuvenator was needed during the rejuvenator optimization process. Overall, it can be deduced that from the binder-scale point of view, the mixture containing the introduced recycled plastic additive could be recycled for multiple life cycles without any degradation of its mechanical and physical properties.

Evaluating the Ageing Sensitivity of the Asphalt Binder via Distinct Ageing Methods

“…In this study, a Bruker Tensor 27 FTIR with an attenuated total reflectance (ATR) diamond crystal was employed to analyse the changes in the chemical functional group of the aged binders. This technique identifies chemical functionalities corresponding to distinct bonds or functional groups as a function of wavenumber by determining the infrared light absorbed by the bonds in molecules when its frequency matches the vibration frequency of the bonds [3]. The literatures showed that the spectral peaks corresponding to the wavelengths around 1030 cm −1 (sulfoxide group) and around 1700 cm −1 (carbonyl group) are significantly affected during the ageing process.…”

“…The G indicates the lost deformation energy of the material and serves as the viscous component of the material, whereas the G represents the energy stored in the system and reflects the elastic part of the material. The parameter G is directly proportional to the loss factor that often depicts material losses, and which indicates the softness or hardness of the asphalt binder [3]. Since G -G equilibrium indicates the structure of a material, a rheological investigation employing this approach is regarded as valid for evaluating the behaviour of the ageing of asphalt binders.…”

“…However, over time, asphalt pavements undergo oxidative ageing processes due to climatic volatility and chemical reactions. Consequently, the asphalt binder becomes increasingly stiff and brittle, leading to higher susceptibility to cracking and degradation of the pavement [3,4]. It is crucial to identify the ageing mechanism of asphalt binders to implement strategies that can extend the service life of the pavement.…”

Life Cycle Assessment of Environmentally Friendly Solutions for the Construction of Unpaved Rural Roads

“…Recycled materials of different origins, such as construction and demolition waste [7][8][9][10][11][12][13], plastics [14][15][16][17][18][19][20], rubber [21][22][23][24][25][26], reclaimed asphalt [10,19,24,25,[27][28][29][30][31][32][33][34][35][36][37], and mineral sludge [38][39][40][41][42][43][44], have the potential for recycling in road pavement materials, making the performance of the corresponding mixtures in which they are employed comparable to those obtained with totally virgin components.…”