37% RAP, 5% RAS in Chicago? in December?
Dec 15, 2010
It was so cold that the drum was frozen on December 2nd. It was 25 °F for a 5:30 am start. The plant eventually warmed up enough that Bigane Paving could start running a PG58-22 mix that contained 37% RAP and 5% RAS along with Evotherm for a City of Chicago alleyways project. Bigane supplied the mix from their own paving crew and to a Chicago DOT crew. Production temperature lined out at 355-365 °F and was delivered at 330-340 °F. Uncorrelated Troxler density ranged from 94-97.1.
This was a proof of concept project that showed the addition of Evotherm would allow the plant and contractor to use a stiff, high recycled content mix for winter condition paving without sacrificing performance and workability. Normally at this time of year, this mix would have been too stiff to use. A different mix with much lower recycled content and higher virgin AC content would be required. Evotherm saved money on AC by increasing recycled content and reduced equipment wear and tear by lowering the production temperature to 325 °F from 365 °F.
All parties involved were very pleased, to the point that STATE Testing president Jay Behnke was willing to invite elected officials from Springfield, IL to come up and witness the paving. These officials represent the Chicago wards and are very excited about environmentally friendly projects going on in their areas.
Author: Jason Mapes
