Reuse of paint sludge in road pavements: Technological and environmental issues

Abstract

This paper presents some of the results obtained in a research project focused on the use of paint sludge (PS) as a modifying agent in the production of bituminous binders for paving applications. The scope of the project was to provide an innovative, sustainable and profitable solution to waste management problems which automotive industries have to face worldwide as a result of the production of PS. The authors applied for a patent which defines the industrial process for the production of PS modified binders (PSMBs). Measurements and analyses which were considered relevant for the assessment of technological feasibility included evaluation of: PS physical characteristics, PSMB high-temperature viscosity and PSMB storage stability. Environmental issues were addressed by considering PS chemical composition, gaseous emissions during PSMB production, and leaching behavior of bituminous mixtures containing PSMBs. Obtained results show that with a proper adaptation of the PSMB production process (i.e., PS drying at a higher temperature than 105°C) it is possible to comply with technological and environmental requirements such as those related to storage stability and to gaseous emissions during PSMB production and laying of bituminous mixtures. Leaching tests, aimed to evaluate runoff water quality, show no substantial difference in the release of substances in water between standard bituminous mixtures and bituminous mixtures prepared with PSMBs.

Sustainable options for paints through a life cycle assessment method

“…For this reason, there is the need to compare scenarios using LCA and to analyse solutions that help replace toxic substances. Zanetti et al (2018) investigated the use of paint sludge in the automotive industry by modifying an agent of bituminous binders for road pavement. The authors assume this a good alternative to landfilling or incineration.…”

Cost analysis and environmental assessment of recycling paint sludge in asphalt pavements

“…The authors concluded that the addition of amounts of PS up to 20% determined only minor changes in the physical properties of asphalt binders, in terms of performance grade (PG), elastic response, stress sensitivity, fatigue resistance, and fatigue ductility of neat bitumen. Furthermore, a subsequent study of the same authors (Zanetti et al 2018 ) proved that the impacts on the environment of the phases of production of HMAs with a PS-modified binder and of the subsequent construction of the pavement were of limited extent. In fact, with an adequate tuning of the operating conditions of the recycling process (i.e., a drying process of PS carried out at a temperature value in the range 105–150 °C), the quality of the gaseous emissions generated during the phases of HMA production and lying did not relevantly differ from those obtained by producing and lying traditional, unmodified HMAs containing neat bitumen (Zanetti et al 2018 ).…”

“…Furthermore, a subsequent study of the same authors (Zanetti et al 2018 ) proved that the impacts on the environment of the phases of production of HMAs with a PS-modified binder and of the subsequent construction of the pavement were of limited extent. In fact, with an adequate tuning of the operating conditions of the recycling process (i.e., a drying process of PS carried out at a temperature value in the range 105–150 °C), the quality of the gaseous emissions generated during the phases of HMA production and lying did not relevantly differ from those obtained by producing and lying traditional, unmodified HMAs containing neat bitumen (Zanetti et al 2018 ). Similarly, the presence of PS in the binder of an HMA did not negatively affect the quality of the leachate obtained by putting in contact asphalt concrete samples with water, according to the EN 12457/2 method (EN 12457-2 2002 ), with the aim of simulating the characteristics of runoff water.…”