Innovative Uses of Recycled Rubber in Urban Design and Infrastructure
Stone. Wood. Concrete. Steel. When thinking about the materials that comprise our built urban environment, it might be easy to overlook an innovative product: recycled rubber. While it can be overshadowed by more traditional building materials, recycled rubber offers a myriad of benefits that contribute to both sustainability and durability in our infrastructure.
In addition to its sustainability benefits, recycled rubber has many facets that make it a well-suited building material for cities. Recycled rubber products are durable and flexible, making them ideal to use in hard-to-reach and variable environments. Additionally, recycled rubber has superb acoustic insulation properties, helping to lessen noise pollution.
Below we explore some uses of recycled rubber in urban design and infrastructure.
Recycled rubber in asphalt
Rubber-modified asphalt (RMA) uses crumb rubber in the construction of new roads. Resistant to cracking and rutting, RMA dramatically increases the lifespans of roads and cuts costs by 43%. RMA creates smoother pavements, which leads to better ride quality for drivers and a significant reduction in tire wear. Moreover, the use of RMA produces 32% less CO2 emissions than regular asphalt.
Despite all of these benefits, the use of rubber-modified asphalt is still limited. The current market for RMA uses just 3% of the total scrap tires generated in the U.S. annually. With an estimated 8.7 million miles of road lanes across the U.S. and recent federal investment in infrastructure, there is ample opportunity to recycle more scrap tires and expand the use of RMA.
Recycled rubber in tire-derived aggregate
Recycled rubber can also be used to produce tire-derived aggregate (TDA), which is composed of shredded tires, ground into small pieces of varying sizes. TDA can be utilized in civil engineering projects like filing and embankment or supporting a retaining wall, as well as an environmentally-friendly alternative to traditional construction materials. TDA can reduce vibration and noise from trains when placed beneath and in between the tracks, a method that has been used by California’s BART and L.A. Metro systems.
The material is also more affordable than traditional methods of noise reduction and saves transportation agencies—and by extension, taxpayers—money. For example, San Jose used 1,000 tons of TDA in a light rail expansion project, saving over $1 million.
Recycled rubber in poured-in-place surfaces
Recycled crumb rubber can also be used as a poured-in-place surface, perfect for playgrounds and sidewalks. As opposed to traditional concrete, which is a hard, immovable surface, recycled rubber surfacing has a slight give to it. This makes it a better-suited material for playgrounds, where it can cushion falls. Studies show that all rubberized surfaces can effectively cushion falls with some able to protect against falls from heights of up to 12 feet.
For sidewalks, it can easily be installed on slopes, around curves, or over mounds, like tree roots, that regularly render sidewalks unusable. With poured-in-place recycled rubber surfacing, the sidewalks can be installed directly over tree roots without damaging or hindering growth.
Next time you go for a walk, run, train ride, or drive, know that recycled rubber plays a critical, if unheralded, role in helping you get to where you want to go.