Production of new bituminous materials (ecobinders)by recycling waste oil and rubber from end-of-life tire ("Crumb Rubber")

Abstract

Nowadays the main problems faced by applied research and industry are towards environmental issues such as global warming, carbon footprint, reduction of greenhouse gas emission amongst others. The Kyoto Treaty was developed as a result in 1997 to setting the objective for European countries to develop policies and technologies in order to meet greenhouse gas reduction requirements. In this light, the asphalt industry accordingly implemented measures to facilitate eco-friendly operations. Examples of some of these measures include the introduction of the use of Warm Mix Asphalt (WMA) and Reclaimed Asphalt Pavement (RAP) which reduce production costs and reduce CO2 emissions. Another initiative used to address environmental problems is resource conservation which has made the use, recovery and recycling of resources more practical and effective in not only reducing production costs but also in making a regenerative circular economy. An example of this initiative is an innovation called End of Waste (EoW) product through which waste is converted into a new product and it is proving very practical and effective in recent times. The End of Waste (EoW) criteria means recovery and treatment processes under which waste could be converted in a new potential product. In particular, according to the European normative the main requirements for a given waste - possibly treated by industrial processes - to satisfy the EoW qualification are the following: a) the substance or object is intended to be used for specific purposes; b) there is a market or demand for this substance or object; c) the substance or object meets the technical requirements for the specific purposes and complies with the existing legislation and standards applicable to the products; d) the use of the substance or object will not lead to overall negative impacts on the environment or human health (in accordance with the Substance of Very High Concern (SVHC) list) From this perspective, the reuse of opportunely re-refined exhausted oils from automobile and industrial hydraulic applications - that have become unfit for the use for which they were originally intended - completely fulfil the circular economy goals. This PhD thesis deals with the conversion of End of Waste Product (EoW) in the form of Re-refined Engine Oil Bottom (REOB) obtained from exhausted oil regeneration processes – through the addition of recycled industrial waste materials - to high performing bituminous binder suitable for use in asphalt mix production. This can save the asphalt industry an even larger amount of resources if it is normalized to practice using this new potentially revolutionary binder together with Reclaimed Asphalt Pavement (RAP) which reduces the need for virgin aggregates in asphalt mix production. Indeed, in the present work asphalt concrete samples have been obtained by using 100 % Reclaimed Asphalt Pavement (RAP) aggregates. The asphalt concrete samples thus obtained underwent testing in order to study their behaviour with the goal to substitute virgin aggregates that are commonly employed in asphalt pavement. This would allow to reach the standards of most of the European countries where RAP is already used in the range of 70-90%, while up to now in Italy a maximum of 30% of RAP is used in the Hot Mix Asphalt (HMA) and Warm Mix Asphalt (WMA). The aged and more brittle bituminous binder that coats the aggregates limits the use of RAP material as it stiffens the resulting asphalt mixtures making the pavements more brittle and sometimes more prone to cracking especially at low temperatures. To overcome this problem a rejuvenating agent could be used.