Potential Carbon Footprint Reduction for Reclaimed Asphalt Pavement Innovations: LCA Methodology, Best Available Technology, and Near-Future Reduction Potential

Diana Eliza Godoi Bizarro,Isabel Nieuwenhuijse,Elisabeth Keijzer,Mara Hauck,Zoran Steinmann

doi:10.3390/su13031382

Abstract

The carbon footprints of asphalt mixtures with increasing reclaimed asphalt pavement (RAP) content were estimated using a life-cycle assessment methodology. Three asphalt mixtures with different applications and technical requirements, namely porous asphalt (PA), stone mastic asphalt (SMA), and asphalt concrete (AC), were included. The technology leaps needed to achieve asphalt mixtures containing up to 93% RAP were modelled. Mixtures containing up to 57% RAP were hot-mix asphalts (175 °C), while mixtures containing more RAP were produced at 135 °C and 105 °C. The energy requirements and their respective carbon footprints were calculated based on the heat capacity of the aggregates, RAP, and other bituminous materials. Furthermore, the effects of changing the country’s electricity mix were also evaluated. A potential carbon footprint reduction of between 55% and 64% was found for one tonne of asphalt containing 93% RAP and produced at 105 °C compared to the 0% RAP mixture produced at 175 °C. Considering the uncertainty of this technology at its early stage of development, the reduction could be as low as 45% or as high as 79%. Changing the electricity mix to one that is likely to be implemented until 2030 in the Netherlands further reduces the footprint by 10%.

Highlights

Published: 28 January 2021With the signing of the Paris Agreement in 2015, almost all countries have pledged to reduce their greenhouse gas (GHG) emissions drastically
The aim of this paper is to propose and apply such an approach for the example of asphalt with varying degrees of reclaimed asphalt pavement (RAP) that exceed the ones previously addressed in peer-reviewed life-cycle assessment (LCA)
Use phase, and end of life are excluded from the analysis because the RAP-containing asphalt mixtures are considered to be of equal quality in terms of workability and lifetime compared to their conventional counterparts, making these latter stages identical

Summary

Introduction

With the signing of the Paris Agreement in 2015, almost all countries have pledged to reduce their greenhouse gas (GHG) emissions drastically. Emission reduction targets have been implemented or proposed for many different sectors, including the road construction sector. The road construction sector is responsible for more than 5% of GHG emissions generated in Europe [1]. Choosing asphalt mixtures with lower carbon footprints can contribute to reaching a country’s climate change reduction targets [2]. Rijkswaterstaat (RWS), the Dutch road authority, established a goal of GHG emission reduction by 30% by 2020 in comparison to 2009, and it aims to be a carbon-neutral organisation in 2030 [3]. About 90% of the carbon footprint of asphalt roads in the Netherlands is concentrated in the production of raw materials—bitumen and crushed stone—

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