Environmental Performance of Road Asphalts Modified with End-of-Life Hard Plastics and Graphene: Strategies for Improving Sustainability

Abstract

Road construction takes a heavy toll on the environment. Therefore, innovative strategies to improve the environmental performances of this sector are needed, and the use of recycled materials (e.g., plastic) has been recently pursued to achieve this goal. The present work aims to (i) assess the environmental benefits deriving from the use of recycled hard plastics in combination with graphene to generate a new bitumen modifier and related asphalt mixture (AM) formulations (ii) to compare the performance of the bitumen modified using this new modifier with the bitumen modified using a traditional polymer (Styrene-Butadiene-Styrene, SBS) and the non-modified bitumen. A detailed Life Cycle Assessment (LCA) study was performed according to a cradle-to-cradle approach. Different scenarios were compared, including the variability of the pavement’s layers thickness and the amount of reclaimed asphalt pavement during the road maintenance cycles. The results demonstrated that the addition of the innovative modifier enhanced the structural performance of AMs, which turns into pavement extended durability, reduced maintenance cycles as well as into reduction in raw material use. The innovative asphalt modifier also creates a synergistic effect by offering a valuable alternative to hard plastic incineration by using it as a secondary raw material. This analysis allowed us to indicate the new-modified AM as the solution with the least environmental burden in all impact categories, suggesting its significant role in implementing new strategies to improve the environmental sustainability of road pavements.

Life Cycle Assessment of Road Pavements That Incorporate Waste Reuse: A Systematic Review and Guidelines Proposal

“…OpenLCA 2.0 offers a modular platform for life cycle analysis and sustainability assessments. This opensource software can connect to an online database, but the Ecoinvent database must be purchased separately [19,21]. CMLCA 6.1, geared toward supporting the technical aspects of LCA, offers robust data analysis capabilities, including a comprehensive matrix algebra tool with matrix inversion and built-in methods for sensitivity analysis and uncertainty assessment [64].…”

“…Notably, the number of software programs used was greater than the number of articles; one study used more than one program to carry out its analysis [19]. As SimaPro is the most widely used software; it was the choice of 15 different nationalities analyzed in this research.…”

“…Notably, the number of software programs used was greater than the number of articles; one study used more than one program to carry out its analysis [19]. As demonstrated by the authors, the use of multiple software programs, such as GaBi and OpenLCA, can initially offer a more comprehensive approach to assessing environmental impacts, allowing for the exploration of different perspectives and functionalities offered by each program.…”

“…Among the waste materials used as substitutes are reclaimed asphalt pavement (RAP) [13], tire rubber [14], construction and demolition [15], glass [16], slag [17], fly ash [18], plastics [19], fibers [20], bio-oil [21], roof tiles [22] and polymers [23]. These materials have been applied to the different layers of the paved road, from the asphalt coating in the top layer to the lower layers, such as the base, subbase, and embankment.…”

Modified Asphalt with Graphene-Enhanced Polymeric Compound: A Case Study

“…In particular, these compounds generally improve the mechanical performance of the material and increase its durability [43,46]. At the same time, they significantly reduce the environmental impact [47].…”