Plastic waste use as aggregate and binder modifier in open-graded asphalts

Abstract

The rapid urbanization growth results in higher traffic levels creating the need for roads with improved performance. However, building a road pavement requires large amounts of materials, and their extraction can lead to the devastation of natural resources and cause negative impacts on the environment. The asphalt mixture, a matrix of aggregates linked with an asphalt binder, is one of the most important materials used for road paving. The aggregates represent approximately 90% of asphalt mixtures, and the alternative of their partial substitution by plastic wastes can be considered as a sustainable technology, since an equivalent performance can be assured (Robinson, 2004). Regarding the asphalt binder, it is the most valuable constituent and largely responsible for the asphalt mixture performance (Becker et al., 2001). One method often used to improve the asphalt mixtures mechanical performance is the addition of polymers (Becker et al., 2001), which can be applied in asphalt mixtures by using the wet method (as asphalt binder modifier) or the dry method (when the polymers are added to the aggregates). However, the use of virgin polymers can even double the final price of asphalt binders (Kalantar et al., 2012). The use of plastic wastes, instead of virgin polymers, can be a good answer for that economic concern, being also a better environmental solution. Besides the road mechanical performance, related to the durability and structural design of asphalt road pavements, the pavement must also provide a safe, comfortable and noiseless surface. These functional characteristics are related with the tire/pavement interaction, adhesion and noise, and the projection of water in wet weather, which in turn are related with the porosity, the surface texture, and the incorporation of polymers (usually elastomers) (Biligiri, 2013). Open-graded and porous asphalts mixtures are frequently applied in surface layers due to their ability to reduce water splash, aquaplaning and noise, promoting the adhesion between the

Turning Waste Cooking Oils into Biofuels—Valorization Technologies: A Review

“…The bed temperature depends on the type of material to be gasified, for example, in the case of biomass, due to high volatile content and with a low melting point, the bed temperature must be between 800 and 900 • C. In the treatment of waste, some processes operate at higher temperatures to guarantee their complete decomposition. The ashes produced during this process are removed from the bottom of the gasifier [40,43,51,54]. According to Tamošiūnas (2019), fluidized bed gasification was developed to solve operational problems, such as a mixture of gas-solid contact, uniformity, temperature control, and efficiency.…”

“…In the treatment of waste, some processes operate at higher temperatures to guarantee their complete decomposition. The ashes produced during this process are removed from the bottom of the gasifier [40,43,51,54]. Kim (2015) carried out WCO valuation studies of soy oil to produce syngas gasified with air in a fluidized bed reactor.…”