BLENDS FOR SUSTAINABILITY
By TA News Bureau :
Recycling of end-of-life tyres is catching up the world over. Many innovative technologies are being developed for the environment-friendly use of waste tyres as alternative raw materials. From tyre-derived fuel to moulded rubber products, ELTs are finding new uses such as in civil engineering applications, agricultural and recreational uses. Dr Davide Lo Presti of Nottingham University is a research pioneer in tyre recycling who has done extensive studies on using ELTs in rubber-modified asphalts. In an interview to Tyre Asia, he explains his research in recycled tyre rubber modified bitumen (RTR-MBs) to enhance performance of road’s pavement. His emphasis is on incorporating sustainable engineering within the transport infrastructure sector
Dr Davide Lo Presti from Nottingham University is upbeat about his extensive work on technologies for re-using waste/secondary materials such as tyre rubber, reclaimed asphalt etc into civil engineering applications such as roads, railways and roofing membranes.
Through international cooperation with a consortium of 30 partners he is currently working on developing tools, methodologies and concepts for a more sustainable management of transport infrastructures and related technologies where waste tyre is a major component.
Elaborating on his vision of Sustainable Multi-Functional Automated Resilient Transport Infrastructures and other related issues, he says globally the current research in exploring solutions for using rubberised asphalt and bitumen-rubber blends in civil engineering is aimed at addressing the problems of disposal of end of life tyres.
Dr Davide, who is a Senior Scientist and international research project manager at University of Nottingham, says his work on sustainable use of ELTs is more relevant now than ever before because of economic and social advantages of tyre recycling.
In the past 3-4 years, while the amounts of ELTs that are freely available are on the increase, the price of synthetic polymers such as SBS has been seeing great fluctuations. This aspect alone provides a valid technical and economic reason to keep on pursuing research to tailor bitumen-rubber blends that incorporate the highest amount possible of re-used tyre rubber in place of commercial polymers, he points out.
“The applications are mainly for asphalt mixtures for road pavements or railway trackbeds and roofing membranes, with the latter showing a huge space for improvements,” he says in an interview. The technical challenges are huge and restrictive but on different terms.
The use of tyre rubber allows making of products that could compete with those that are commercially available. It is so in both economic and technological terms. It will also improve the steady uptake of tyre rubber as replacement of synthetic polymers within this market, It’s necessary to continue research in tailored solutions that pre-treat the tyre rubber to make it compatible for further applications.
“However the real challenge is not technical alone,” he says. “In fact the change must come first from political will and also from a possible involvement of the tyre Industry.” The civil engineering sector represents a huge possibility for revamping waste materials of other industries. However, there will be no significant space for reuse of alternative materials unless specifications are modified.
Government policies should favour recycling practices through incentives such as tax benefits and/or creating markets for the “green” products, he strongly feels.
Dr Davide believes that the use ELTs in civil engineering is one of the best ways to address sustainable environment issues. “It certainly is one of the ways due to the potentially huge amount of their possible re-use and it has already shown in several successful cases.”
For decades the use of ELTs in different forms has existed and technologies have been available. They have shown very few drawbacks and allowed re-using a significant amount of such material.
He asserts that with a well-established circular economy, these forms of solutions must be considered seriously. There should be widespread application on a large scale.
In terms of environmental benefits, the real advantage of re-using tyres is in civil engineering. It offers immediate possibility of uptake of these alternative materials. This would significantly reduce environmental hazards. Tyre manufacturers, distributors, users and the recovery sector should have an active stake in these efforts.
“The tyre industry should recognise that incorporating their end-of-life products within a different cycle does solve an issue that nowadays is managed by significantly devaluing their products (i.e. burning, landfilling, shipping to other countries, etc.). This is often accompanied with an unnecessary vast amount of carbon getting released.”
For these reasons industries and governments need to talk and strive to find common solutions. However, this can be successful only if there is clear political support in developing an efficient circular economy.
Dr Davide, who has done extensive work on improving the rheometry of rubberised bitumen by conducting computational fluid dynamics studies, says that it has been one of the technological challenges that he has faced in his research.
He says the bitumen technologist and practitioners nowadays face the challenge to correctly measure the rheology of such a complex material. In fact, design and quality control of rubberised binders are crucial as one has to be aware of the rheological properties of the binders.
“At the University of Nottingham, we have developed procedures that allow obtaining realistic viscosity measurements of these complex fluids in real-time during the manufacturing of the rubberised binders.”
For this purpose, the researchers have prototyped improved testing geometries that would allow use of rotational viscometers and dynamic shear rheometers, also as low-shear blenders. The setup will allow real-time monitoring of the modification process together with more realistic viscosity measurements of complex fluids with tendency to phase separation.
The Computational Fluid Dynamics (CFD) work has been propaedeutic to having an insight on the mixing capabilities of the existing testing geometries for rheological measurement of complex fluids as well as a platform to design improved shapes.
“We will try out the use of this platform also to perform design and quality control directly by computational rheology,” Dr Davide says.
Referring to the benefits of research on crumb modified bitumen, he says his aim is to introduce sustainability criteria and targets within civil engineering. Effectively re-using alternative materials within this sector is a big challenge that research centres, governments and societies should immediately take up, he suggests.
“Rubberised binder is a technology that works and that must be considered as a first option to replace polymer modified bitumen,” he asserts. “I would be happy to support anyone who is trying to expand the field of application of this technology as well as those who are trying to find suitable pre-treatments to effectively use tyre rubbers as alternative material for civil engineering applications and beyond.”