NORTHBRIDGE, Mass. – One worker, his body under clothing encased in a suit of circulating ice and water, his head and face protected with helmet and shield, rode on the back of an asphalt truck last Friday morning as it sprayed a layer of asphalt rubber to Quaker Street.
The asphalt was blended with the rubber of scrap tire treads and heated to more than 350 degrees. The hot, dangerous job of the boot man is to use a pick to unclog spigots that sometimes are blocked by the mixture.
The inky black of the rubber asphalt is green for the Northbridge Department of Public Works, noted Highway Superintendent Rob Van Meter. “Hot in place asphalt recycling is very green,’’ because it recycles the tread of scrap tires, he said.
In addition to reducing the waste stream, the tires serve another process, Van Meter said. The rubber is petroleum based, so when melted adds another level of flexibility to the finished product.
Instead of cracking with temperature change, the asphalt moves. “It’s cost effective and it stands up to plows,’’ he said.
The two-phase restoration project of Mendon Road and Quaker Street started in July when a company from Brewster, N.Y. used infrared heaters to melt, mill and scarify the existing pavement, then added a rejuvenating agent to restore flexibility to the surface.
A few weeks were needed for the first phase of the process to settle, and the second phase was completed last week.
Following closely behind the asphalt-spreader on Friday was a chip spreader, and behind that a truck filled with chips – small irregularly shaped rocks which are fed onto two conveyor belts connected to the chip spreader.
As the asphalt was laid, the chip spreader followed, spreading rock on top of the asphalt. Behind the chip spread were rollers, the job not to compress but to orient the edges of the rocks so they lock together like puzzle pieces, Van Meter said.
Lines will be painted on the finished roads this week.
The road maintenance project was made possible by voters in May who approved the expenditure of $635,000 as part of a five-year, $2.5 million road maintenance program. The remainder of the cost will come from the state.