Rubber Technology International (fka RTEK)

[KauaiPI]

from NJ DOT concerning use of CR in asphalt mixes

Thanks to Yocrispy

http://ragingbull.lycos.com/mboard/boards.cgi?board=RTEK&read=22380

...response from NJ DOT concerning use of CR in asphalt mixes:

Thank you for your interest in New Jersey's use of scrap tires in asphalt pavements. As part of a cooperaative effort with the NJ DEP, the NJ DOT began to investigate the possible use of recycled materials, including scrap tire rubber, as highway construction materials around 1990.

The following is the current status of the DOT's scrap tire evaluation:

The NJDOT has used a crumb rubber modifier(CRM) in its hot mix asphalt(HMA) pavement design on six demonstration projects. Different types of pavement mixes were evaluated. Included in this assessment was an evaluation of the dry vs. wet mixing process, as well as the effect the rubber had on air quality. These projects were placed in the first half of the nineties. Monitoring for rutting, roughness and cracking continues. So far most of these projects have shown no significant potential for increased or decreased pavement life. They seem to be performing equally to the control test sections. However, just recently a test section placed in 1994 appears to be exhibiting much less fatigue cracking than its control section. The McDonald wet process was used in this section-monitoring continues.

Air quality emission tests showed that the "wet process" just met the maximum emission standards, and that the "dry process" did not! Besides the environmental concerns this raises, the increased costs involved with mixing the crumb rubber into the asphalt binder may be too costly when compared to the small amount of tire volume actually used. However, it should be noted that the states of California and Arizona appear to have had more sucess with crumb rubber. Because of their warmer climates they have been able to reduce the pavement thickness by half, when the mix is modified with crumb rubber.

A "carbonous powder" material derived from a patented process which combines waste motor oil and rubber tire chips is currently being studied along with other polymer modifiers to determine if it can be a viable and competitive equal to polymer modifiers in HMA mixes. Results from the research project are expected this summer.

Overall, the Department believes that the long term performance and durability of crumb rubber modified HMA in cold weather regions, like NJ, is questionable. However, it does appear to be successful in preventing rutting, without fatigue cracking, where year round temperatures remain warm.

I hope this information is useful in your endeavor. I may be reached at [phone] if you have any questions.

Sincerely,
Frank Palise
Manager
Quality Assurance and Improvements Unit
Bureau of Quality Management Services
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Well, I found the bit about warm weather applications giving more success, particularly because thickness can be reduced, interesting. Thick pavement seems to release alot of VOC's too if I read it correctly. This should mean that the west coast and south should be in the market for this stuff in the future. And we will be there!
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Thanks Yo! Now I wonder what they DO with their scrape tires?