The paver was fed by a Cedarapids windrow elevator. Breakdown rolling was being done by a Cat CB-534D vibratory steel tandem roller, making three passes.
A Cat PS-360B pneumatic roller was making seven passes in the intermediate spot. And a finish roller - an Ingersoll-Rand DD-110HF articulated double-drum compactor - was making five passes in static mode.
Mix was being produced at the plant at or below 235 deg F, compared to a conventional mix produced at temperatures above 290 deg F, and was being placed at about 220 deg F.
WMA temperatures averaged 230 deg F in the windrow, 220 deg F by the paver, and the finish roller was compacting at 130 deg F, which is quite low. "The driving factor is the temperature in the baghouse," Dosh says. "The temperature has to be kept above the boiling point so water will not condense in the bags. We could produce at a lower temperature if not for the baghouse."
The county may get an added benefit. Because WMA is not as dependent as HMA on heat to provide the workability needed to get density, the county may be able to extend its paving season, which is limited in the northern tier of states.
"From what I've seen, WMA will be an excellent way to extend the paving season," Dosh says. "We usually run out of time to pave. We are doing well if after base construction, we get our first course down before snow flies. We typically are not supposed to place asphalt after Sept. 15 in the northern part of the state. And due to weight restrictions following the winter thaw, we can't start hauling heavy loads like asphalt from the middle to the end of May, depending on the kind of winter we've had. If there's been a long, cold winter, it might be the first of June before we can pave. We are looking at a paving season of 120 days, longer if there is a warm fall, but you can't depend on that."