Today, scrap tires are utilized in various industrial applications and consumer products. Despite the increasing number of uses, a significant surplus of scrap tires remains available for recycling, with many tire stockpiles worldwide expected to last for decades.

Researchers assert that many scrap tires can be effectively reused in concrete. Not only can the rubber be repurposed, but other materials found in tires, such as recycled steel and synthetic fibers, can also enhance the properties of concrete. This article summarizes recent research findings on this topic.

Fatma Sulaiman Nasser al Kindi, a chemical engineering student at Caledonian College of Engineering in Oman, emphasizes that tire recycling enables the creation of alternatives to conventional aggregates used in concrete production. She explains that scrap tires are reduced to crumb rubber of various sizes during recycling. This processed material can then be mixed with concrete or serve as raw material for other types of pavement. Fatma notes that crumb rubber acts as a binding component in blends, helping to prevent initial cracks in concrete slabs.

Other researchers have also explored the use of recycled rubber in concrete mixes to enhance the durability and resilience of concrete. This approach has shown promising results, extending the lifespan of concrete structures, roads, and bridges.

An EU-funded project led by experts from the University of Sheffield and Imperial College London, in collaboration with the European Tyre Recycling Association, has demonstrated through extensive experimental work that all tire components can be successfully incorporated into concrete. The project team claims that recycled rubber allows buildings and other structures to flex up to 10 percent along their length—50 times more than structures made from traditional concrete. Furthermore, they found that the ASTM1080 steel tire wires can be blended with other steel fibers to increase the flexural strength of concrete. This innovation saves on virgin materials and reduces energy requirements by 97 percent. The wire’s smaller size compared to conventional steel fibers means more fibers in the concrete, aiding in crack control at the micro-level.

The researchers also identified that textile polymer fibers, primarily used as reinforcement in passenger tires, possess high quality and strength. These fibers can help control cracking during the early stages of concrete curing when the material is still plastic. The Sheffield team has demonstrated that textile fibers can prevent explosive spalling of concrete during fires, leading to potential applications in tunnels and buildings.

Plans are underway to utilize this new concrete material in seismic-resistant buildings, vibration isolation, and bridge bearings. As part of the EU-funded Anagennisi project, demonstration projects will be carried out in several countries to showcase the benefits to contractors and infrastructure owners.

In North America, a University of British Columbia team supports the Sheffield team’s findings. They have developed a more robust and resilient type of concrete using tire-derived fibers. According to the UBC team, this new concrete can be employed in constructing buildings, roads, dams, and bridges.

The UBC team experimented with different proportions of tire fibers to find an ideal mix, eventually determining that 0.35 percent tire-derived fibers yield the best results. Obinna Onuaguluchi, a postdoctoral fellow in civil engineering at UBC, asserts that including these fibers reduces crack formation by over 90 percent compared to conventional concrete. While traditional concrete structures can develop micro-cracks over time, polymer fibers help protect the structure, enhancing its durability.

This research was supported by organizations like IC-IMPACTS, Tire Stewardship of British Columbia, Atlantis Holdings, and Western Rubber Products, which provided tire-derived fibers to UBC. Recent research by Figueiredo, Huang, Angelakopoulos, Pilakoutas, and Burgess also investigated the effects of clean, recycled fibers extracted from end-of-life tires on fire-induced concrete spalling. After conducting 24 spalling tests, the team concluded that “recycled tire steel fibers show the potential to prevent fire spalling damage by keeping spalled concrete attached to the heated surface, thus protecting the main steel reinforcement. These fibers could lead to safe and sustainable fire spalling mitigation solutions.”

This body of research supports the notion that recycled tire-derived materials can have broader applications in industry. To encourage innovation and increase the use of recycled tire-derived materials in concrete, larger-scale pilot projects and collaborative efforts among industry stakeholders are necessary.

Klean Industries conducts comprehensive market studies and guides businesses in tire recycling through collaboration with research institutions and industry experts.

To learn more about the work done by Klean Industries with Atlantis Holdings, Liberty Tire recycling (Western Rubber Products), and the University of British Columbia, please follow this link to our project section for more info » GO.