Environmental impact of rejuvenators in asphalt mixtures containing high reclaimed asphalt content

M Muñoz,R Haag,R Figi,C Schreiner,M Zaumanis,M C Cavalli,L D Poulikakos,N V Heeb

doi:10.1080/14680629.2021.1891129

Abstract

ABSTRACT The use of reclaimed asphalt pavement (RAP) is of increasing importance due to fast-growing amounts of demolished road materials. However, reclaimed asphalt can contain relevant amounts of pollutants such as carcinogenic polycyclic aromatic hydrocarbons (PAHs) and toxic metals. In order to improve the mechanical properties of recycled asphalt, rejuvenators are used to reduce the stiffness of the aged binder. These rejuvenators in turn may potentially mobilise pollutants like PAHs and facilitate their leaching to surface and ground waters. The environmental impact of three rejuvenators with good mechanical performance was studied. The environmental impact was assessed by determining metal- and PAH contents in the RAP and in leachates. Chemical analyses showed that rejuvenators did not mobilise PAHs from RAP materials for 2–3 ring PAHs. However, some 4–6 ring PAHs that are relatively less toxic indeed leached more easily from unaged material. Ageing reduced the tendency for PAH leaching, without and with rejuvenator.

Highlights

The use of reclaimed asphalt pavement (RAP) to substitute new construction materials has become an important research topic (Antunes et al, 2019; Kaseer et al, 2019) with the potential for various benefits including a reduction of asphalt costs (Zaumanis et al, 2016), an overall decrease of emissions over the entire life-cycle (Chiu et al, 2008), and the conservation of non-renewable natural resources (Mallick et al, 2014)
The focus of the work presented in this paper is to study the environmental aspects of rejuvenator compositions, simulating aging processes at production temperature and determining the potential for leaching and mobilisation of toxic material from the RAP to surface and ground water
Very low polycyclic aromatic hydrocarbons (PAHs) concentrations were found in all tested rejuvenators

Summary

Introduction

The use of reclaimed asphalt pavement (RAP) to substitute new construction materials has become an important research topic (Antunes et al, 2019; Kaseer et al, 2019) with the potential for various benefits including a reduction of asphalt costs (Zaumanis et al, 2016), an overall decrease of emissions over the entire life-cycle (Chiu et al, 2008), and the conservation of non-renewable natural resources (Mallick et al, 2014) Because of these reasons, the use of RAP has steadily increased over the last decades. Measures to compensate for the negative effects of aged binder are necessary

Methods

Results

Conclusion