Dear Readers,

Month by month, our weibold! Academy series dwells deeper into the world of tire recycling and highlights different sides of running this business. In case you have missed our previous articles, you can find the links at the end of this post.

Waste tires in civil engineering

When their lifecycle is over, tires are usually brought to recycling facilities where some of them are shredded into small pieces. As a rule, sizes depend on end applications. Bigger ones find their next life at playgrounds as rubber mulch ensuring kinds’ safety and soft landing at the end of the slide.  Smaller pieces – crumb rubber – are molded into rubber tiles that make cement floors more comfortable for weight lifters, kitchen staff, workers of storage facilities, children on playgrounds, etc. These are the most conventional uses for crumb rubber from tires.

Tire rubber particles can also be used in landscaping.  For instance, plants require less water when mulched with recycled tires.  They even come in a number of fun colors.

Today, one of the promising and evolving fields of application for recycled tires is civil engineering. Dozens of rubber products exist in this field and they pose very different requirements for the material. For instance, rubberized asphalt industry demands crumb rubber of smaller sizes. Sound insulation panels and noise barriers can be manufactured from crumb rubber, too, whereas hydro insulation products such as roofing membranes can only use fine rubber powder.

Yet many potential applications consider super-fine rubber powder as a viable substitute of conventional materials due to the lower price of recycled rubber compared to virgin composites. Notwithstanding, the main challenge is bonding properties of rubber powder. The powder shall act as an active ingredient and not just as filler.

One method to improve these properties is superficial modification. Such high-tech processes of chemical modification ensure good bonding properties and, indeed, enable tire-derived rubber powder to conquer new volume markets.

Image: Mechanical Concrete

Other applications may involve even whole tires. One of the examples is a patented American technology Mechanical Concrete. Samuel G. Bonasso, a fellow of American Society of Civil Engineers, invented this product which is a confined aggregate concrete in waste tires used in the field of geosynthetics. It confines stone aggregates in a thin-walled cylinder. Confinement with tires improves the structural performance of crushed stone and all other aggregate materials. Removing both sidewalls from an end of life tire creates an industrial strength, low cost tire-derived-geosynthetic-cylinder. The product dramatically reduces or eliminates potholes and ruts, road edge & ditch wall collapse, slope and shoulder erosion, soft sub-grade failures, ditch & channel scour, active soil pressure. More information on Mechanical Concrete is Available in our article.

Earlier this year, a research by the University of British Columbia (UBC) in Canada demonstrated how tire-derived fiber can significantly reinforce concrete. Rubber-modified asphalt is not a new technology and roads from recycled tires are found in U.S., Germany, Spain, Brazil, China and other countries worldwide. But the new fiber-reinforced concrete developed by UBC enhances resilience and life time of the material. Researchers pinpoint that the bulk of waste tires end up at landfills and even when recycled, fibers are usually burnt or disposed of. However, if fibers are introduced into concrete, it could diminish tire industry’s footprint and reduce emissions of the whole construction industry (we would like to remind that cement is a major source of greenhouse gas emissions).

About five years ago, civil engineering received yet another application of waste tires in railroad construction. Original railroad ties are made of wood and, in recent years, plastic or concrete. However, these materials are susceptible to rot, infestation and erosion over time. As a result, this can be detrimental to the whole system of infrastructure. But when railroad ties are made of recycled rubber, they last longer and turn out to be much stronger than any other materials.

More trivial applications which already have a steady position on the market are tire shreds. Tire shreds are cost effective, as old tires are usually free. Shredding them is fast and easy and the number of businesses that offer shredding services has been increasing. This makes tire shreds significantly more cost effective than traditional fillers such as gravel and sand.

Also, a good market exists for large-scale construction projects, as massive civil engineering projects require large amounts of shredded tires. For both environment and construction companies it is a win-win situation, as old tires are being disposed of and tax money is saved. Tire-derived shreds offer some benefits that traditional fillers don’t.

Tire shreds have properties that engineers need:

  • Tire shreds are only half the weight of gravel which makes them good for places with poor soil structure, which, in turn, reduces landslides.
  • They promote good drainage, namely 10 to 100 times greater than gravel.
  • They provide thermal insulation 8 times greater than gravel. This insulation decreases the expansion and retraction cycle which helps avoids cracks in bridges and roadways.
  • They have a good ability to transmit water. Water passes through without clogging and damming.
  • Rubber shreds provide long term durability for projects.
  • And they have a very high compressibility. Shreds will drastically reduce in volume when pressure is applied.

Use of recycled tire rubber in civil engineering grows, however tire recyclers should invest in research and development to open new opportunities on existing markets and to target higher-value applications.

To find out more about tire recycling and applications for recycled tire rubber, send us your inquiry to robert@weibold.com. Please contact us to request more information on this topic. We will be happy to help you build a flourishing tire recycling and pyrolysis business!Links to our previous newsletters:

  1. Welcome to weibold! Academy
  2. weibold! Academy: Recycled Rubber Output Spectrum and Rubber Granulates
  3. weibold! Academy: Rubber Granulates, Rubber Powder, Tire Derived Steel and Tire Derived Fiber
  4. weibold! Academy: Tyre Recycling Value Chain
  5. weibold! Academy: Applications for Tyre Recycling Plant Output
  6. weibold! Academy: Rubber Granulate Applications
  7. weibold! Academy: Rubber Powder Applications – Rubber Industry
  8. weibold! Academy: Rubber Powder Applications – Surface Coatings
  9. weibold! Academy: Success Factors in the Tire Recycling Industry
  10. weibold! Academy: Understanding Tire Recycling Technology
  11. weibold! Academy: Total Quality Management in Tire Recycling
  12. weibold! Academy: Applications for Fibers from End-of-Life Tires
  13. weibold! Academy: Safety and health effects of crumb rubber infill in artificial turf
  14. weibold! Academy: Tire pyrolysis – products and applications
  15. weibold! Academy: Tire-derived fuel in cement production
  16. weibold! Academy: How to improve tire collection in small cities
  17. weibold! Academy: How to prevent tire fires
  18. weibold! Academy: Recycled tires in railroad construction
  19. weibold! Academy: Basics about tire-derived fuel