Tire-Derived Product (TDP) Frequently Asked Questions

While regulations provide some flexibility for the color of such mats, in practice most agencies including the California Department of Transportation (Caltrans) requires that they be yellow. Unfortunately, to date we are not aware of vendors offering yellow detectable warning mats made from rubber due to technical challenges.

How do tire-derived products compare to conventional products in terms of greenhouse gas emissions?

There are many government and company studies that have calculated greenhouse gas emissions (GHG) for recycled tire products or competing materials. The assumptions and boundaries for GHG calculations in these studies vary which can make them difficult to compare. Here are highlights from studies that look at recycled tire crumb rubber, concrete and asphalt.

• Recycled tire crumb rubber manufacturer Lehigh compared the GHGs from recycled tire crumb to virgin plastics. Lehigh’s recycled tire crumb generates 0.79 metric tons of CO2 equivalents (MTCO2E) GHG per ton of product whereas virgin plastics generate 1.0-3.1 MTCO2E GHG per ton of product.
• One fact sheet by the National Ready Mix Concrete Association cites EPA data that there are 0.9 – 1.1 metric tons of carbon dioxide equivalents (MTCO2E) released for every ton of Portland cement. Since concrete is about 10-15 percent Portland cement, 15-20 percent water and 60-75 percent aggregate, and the GHG emissions for aggregate are about 0.0046 MTCO2E GHG per ton, overall there is about 0.1-0.15 MTCO2E GHG generated for every ton of concrete.
• EPA’s Waste Reduction Model (WARM) compares GHG emissions for tires that are reused, recycled into crumb rubber for use in molded products, incinerated or landfilled. The net life- cycle GHG emissions of managing one ton of waste tires compared to creating new material is -4.34 MTCO2E for reuse, -0.39 MTCO2E for recycling into crumb rubber for use in molded products, 0.04 MTCO2E for incineration with electricity generation and 0.51 MTCO2E for landfill.
• Finally, a 2008 study by the Institute for Scrap Recycling Industries (ISRI) states that when used in road surfaces, recycled rubber asphalt had between three and seven times lower greenhouse gas emissions than conventional asphalt.

What is the cost per square foot installed for tire-derived products?

Some tire-derived products have higher initial costs than competing products but often lower life-cycle costs because they last longer and require less maintenance labor. Also, tire-derived products often provide other performance benefits compared to competing products. The following cost estimates are based on a 2012 survey of several tire-derived product manufacturers.

How long are warranties that TDP manufacturers offer?

Most TDP manufacturers offer five or ten year warranties that their products will be free from defects in materials and workmanship. Depending on the application, warranties may be as short as two years or as long as 20 years. For example, a preventative tire sealant manufacturer offers a warranty to eliminate punctures for the life of the tire. A water play surface manufacturer offers a two year warranty on their splash pad. Pour-in-place and tile playground surfacing warranties are usually five years. Synthetic turf warranties are often for eight years. A roofing manufacturer offers a 10, 15, or 20 year warranty depending on the thickness of the roofing product.

Are outdoor pour-in-place surfaces permeable to stormwater?

Stormwater percolates through pour-in-place surfaces used for playgrounds, sidewalks and running tracks. The flow-through rates vary widely depending on product design and materials used, ranging from 20 to 350 gallons/minute/square yard. Call or visit websites of pour-in-place vendors for more details you can find contact information on the TDP Vendor List.

Can rubber tiles and pour-in-place sidewalk material be used in parking lots?

Recycled rubber tiles and recycled rubber pour-in-place can withstand limited car parking usage. They are best used in situations where cars pull in and back out only, such as driveways. These products are not necessarily designed for car use as car wheel pivoting that occurs in parking lots is hard on pour-in- place materials and rubber tiles. Stability of the sub-base is essential to the use of these materials. Cost is usually an issue as well. Asphalt costs about $1.50-2.50/square foot installed which is significantly cheaper than tire-derived pour-in-place or tire-derived tiles which may cost $8-17/square foot installed.

When recycling tires, how do recyclers remove steel belts?

Whole tires are fed into either low-speed, high-torque rotary shear shredders or high-speed tub-style grinders. Each time the tire pieces are shredded into successively smaller pieces, powerful magnets pass over the shredded or ground tire pieces to remove pieces of steel belts.

Are tire-derived products used on athletic fields and playgrounds safe for children?

A large amount of research has been conducted on the environmental health and safety aspects of recycled tire products. For example, a 2011 CalRecycle-sponsored study conducted by the California Office of Environmental Health Hazard Assessment (OEHHA) concluded that synthetic turf fields do not pose a serious public health concern, with the possible exception of an increased skin abrasion rate on synthetic turf relative to natural turf.

Additional sources of information include:

• CalRecycle’s Health and Environmental Impacts of Tire-Derived Products page which has compiled dozens of studies.
• In 2009, CalRecycle commissioned California’s Office of Environmental Health Hazard Assessment (OEHHA) to perform a literature review of studies related to artificial turf playing fields. Looking at data from two New York State studies, OEHHA found that “these fields did not constitute a serious health concern, since cancer or noncancer health effects were unlikely to result from these low-level exposures.”
• A 2008 study by ChemRisk, Inc. entitled “Toxicity Evaluations of Playground and Recreational Applications & Civil Engineering Leachate Evaluations” draws the following conclusions after reviewing multiple studies. “The reviewed studies considered the quantitative and qualitative aspects of exposure to classes of chemicals most likely to be inhaled, ingested or directly contacted during athletic or recreational use. While some of the ingredients used in tire manufacturing are considered potentially hazardous to human health at high doses, the potential for athlete or child exposure to these chemicals is very low. Tires are heated during manufacturing to generate physical and chemical reactions which bind the individual chemicals together such that they are inhibited from release into the environment. Studies which assessed exposure from breathing in indoor sporting environments where tire materials are used did not find appreciable adverse health effects. The same conclusion is applicable to outdoor settings, where particulate and gaseous phase air concentrations are expected to be 10 to 100 times lower, due to air dispersion and turbulence.”
• In 2007, CalEPA’s Office of Environmental Health Hazard Assessment (OEHHA) released a risk assessment of the use of recycled waste tires in playgrounds and tracks with a specific focus on children as a susceptible population. The conclusions of this study indicate that there is little risk associated with exposure to recycled tire materials used in playgrounds or tracks.

What is the dye made of that is sprayed on recycled tire products?

The dyes that coat recycled rubber mulch contain various pigments in an acrylic or polyurethane base. For example, the pigments may incorporate iron oxide for red, carbon black for black, titanium dioxide for white and a mix of carbon black and iron oxide for brown. For more information, mulch dye companies such as TH Glennon Company, Colorbiotics, and AmeriMulch have Material Safety Data Sheets.

Can synthetic turf be placed over old pour-in-place on playgrounds?

Synthetic turf has been placed over asphalt or pour-in-place surfaces for playgrounds. The keys to successful installation involve a resilient pad and panel drain below the synthetic turf system.

How does the tire-derived product (TDP) grant program work?

CalRecycle gives grants of up to $150,000 per applicant for tire-derived products. The grant works on a reimbursement basis of $5 per California tire diverted from landfill. Projects must divert a minimum of 2,500 tires per proposed tire-derived project. Visit the CalRecycle site to learn more about Tire-Derived Product grants. Sign up to be alerted when the next grant application period is open. CalRecycle also offers rubberized pavement grants and tire-derived aggregate grants.

Have any cities installed synthetic turf in median strips?

Irvine, Newport Beach, and Fountain Valley in Orange County, California are three examples of cities that use synthetic turf in some median strips.

Does rubberized asphalt concrete, the road pavement made with recycled tires, hold up in areas of California with summer temperatures above 120 degrees fahrenheit?

Rubberized asphalt concrete (RAC) is used throughout California including well-established use in the desert areas such as Palm Springs, Palm Desert, Indio, El Centro, and Brawley. For more information about rubberized asphalt concrete, visit the CalRecycle pavement webpage or contact Mustafe Botan at Mustafe.Botan@calrecycle.ca.gov.

How does the cost of RAC that uses recycled tires compare to the cost of conventional pavement asphalt?

In most applications, RAC can be used at a reduced thickness compared to conventional asphalt overlays–in some cases at half the thickness of conventional material–which may result in significant material reduction and cost savings. In addition there may be life-cycle cost savings from the reduction in maintenance costs and longevity of RAC. See CalRecycle’s web page about benefits of RAC for more information. For details about the grant program, visit CalRecycle’s rubberized pavement grants page.

Can RAC be recycled into roadbase?

Yes, RAC can be ground up and used in place of stone aggregate in roads. CalTrans has used 15 percent RAC on their road surfaces.

What’s the annual nationwide waste tire generation?

According to the latest figures in the 2013 Scrap Tire & Rubber Users Directory the annual scrap tire generation was 308 million tires in 2012. The replacement tire market (sales) for 2012 was 265 million tires including passenger, light truck, medium truck and heavy duty truck tires. Replacement market tires are generally the majority of the tires that enter the scrap tire stream.

The 308 million figure is based on the recognized industry formula of 1 tire per person per year is discarded.

What’s the thickness of the primer sealant?

The primer is approx. 6-8 mils thick per coat, depending on how it is applied (brushed on, rolled on, or sprayed on)

What’s the thickness of the topcoat sealant?

The sealant is approx. 4-6 mils thick per coat, depending on how it is applied (brushed on, rolled on, or sprayed on)

What’s the warranty term for modular sidewalks (how long do they last)?

The company Terrecon offers a 5-year warranty for their product Rubbersidewalks.

What’s the depth for installed pour-in-place pathways and sidewalks?

The chart below shows the total system thickness; the EPDM top layer is always 1/2″ thick, the rest is recycled rubber.

For more information contact: Tire-Derived Products, TireGrants@calrecycle.ca.gov