Raleigh -If you've driven on Interstate 40 in Raleigh over the past year, you've probably noticed the two giant silos that sit along the roadside in the Fortify Rebuild I-40/440 work zone.
The structures are part of a modern asphalt plant built by Fortify's contractor -Granite Construction -that allows crews to be more efficient and environmentally friendly when it comes to resurfacing the 11.5-mile stretch of roadway.
Manufactured by Chatanooga-based Astec Inc., the makeshift plant -it will come down once Fortify is complete next year -is rated to run 350 tons of asphalt per hour and is equipped with what's called a "Generation 2 Green System" that's capable of producing up to 40 percent recycled asphalt. The Green System aids in better coating of the liquid asphalt and helps reduce blue smoke emissions.
All of the asphalt on I-40 will be removed from the roadway, processed and then re-used as the new highway is paved.
Producing asphalt in this manner allows all existing asphalt to be 100 percent recycled.
"All of our mixes currently use at least 20 percent recycled asphalt, with a majority of them using 30 percent," Granite asphalt engineer Michael Maclachlan said.
The plant is equipped with a burner -used to dry and heat all of the aggregates and asphalt -that is efficient in converting natural gas into heat. Several older asphalt plants run their burners using diesel or used oil.
Natural gas is exponentially more efficient, and it burns cleaner than any other option.
In addition to the silos, burner, silos and recycling system, the asphalt plant is equipped with a 74,000 cubic-feet-per-minute baghouse that filters all the exhaust before leaving the plant. There are 1,680 bags -each averaging 12 feet long -that filter and collect dust, allowing cleaner air to exit the exhaust. All of the dust that is produced by the plant is recycled as well. It is injected back into the mix and used in the production of asphalt instead of wasting it.
With each new asphalt plant being built, there is a series of planning and permitting that takes place. One of the many strict objectives of the permit is to test and certify that the asphalt plant does not introduce harmful particulates to the environment. These standards and permitting requirements are set by the North Carolina Department of Environment and Natural Resources.
"According to NCDENR, for a hot mix asphalt plant operating at over 300 tons per hour, the allowable particulate limit is 60 pounds per hour," Maclachlan said. "Our plant ran at 0.6 pounds per hour."
All of the other tests are well in compliance of the testing requirements with similar results.
The Fortify project is scheduled to require over a million tons of asphalt and the plant safety and environmental processes that Granite Construction has in place will ensure that it leaves as little environmental footprint as possible.
Raleigh -Final paving on I-440 West on the Fortify Rebuild Project continues and could be complete the end of next week, weather permitting. Once that is finished, the final traffic pattern and resurfacing can start on I-440 East.
Once complete, I-440 in both directions through the Fortify project will be at full capacity. That means phased construction work on the 8.5-mile stretch of I-40 will increase in the coming weeks.
As work on I-40 ramps up, so will the delays -drivers can expect an average of 30 minutes extra each trip. If you normally take that route to or from work, it is recommended that you find an a