Located just off the coast of Rhode Island is Block Island, and perhaps typical of most island communities commuting by ferry is common for native and tourist alike. This same mode of transportation is also the only way that construction companies get to and perform work on the island. Every piece of equipment, tool, vehicle, laborer, and of course material must be ferried across 18 miles of water from Port Judith.
Last year Block Island needed 1,000 tons of asphalt placed as a surface course on Chapel Street and on sections of Old Town Road. In the past when roads and properties on the island needed paving done a hot mix operation would simply set up a portable plant on the island and produce the mix for the job right there.
But for a variety of reasons that option was not available in 2010, so the contractor and officials looked for other solutions. A few years ago the contractor’s only other option would have been to haul standard hot mix asphalt across a breezy bit of water – and that option was considered.
“The contractor and plant operators decided that if hot mix was used it would have to be produced above the normal allowable temperature limit, essentially over-oxidizing the material for it to have a chance to be hot enough for paving,” says Annette G. Smith, project leader at PQ Corporation. She says that high production heat, combined with the 2 ½- to 4 ½-hour trip from plant to ferry to jobsite, would likely have resulted in unworkable hot mix asphalt and a poorer-quality pavement, or certainly a pavement that wouldn’t last long.
But the contractor who was awarded the bid, T. Miozzi Inc., Coventry, RI, and owner of Miozzi Paving Co., North Kingstown, RI, had another idea: Warm mix asphalt using an additive called Advera® WMA. Produced at temperatures between cold mix asphalt and hot mix asphalt, warm mix asphalt is designed to withstand longer transport times between production and laydown without any adverse effects on density, workability, or pavement life.
“We were not completely sure how the warm mix asphalt would work out but we are confident of our own capabilities as a producer and paving company,” says Thomas Miozzi, the company’s president and owner. But he was well aware there was a concern to overcome.
“There was the obvious question, ‘Can we sustain enough heat in the material to make the working of the asphalt doable for our crew?’”
The answer, it turns out, was yes.
Getting the Job Done
T. Miozzi Inc. produced the warm mix asphalt using the Advera® WMA additive, produced by PQ Corp. “Production temperature was about 290 degrees F,” Smith says. “This is much higher than usual for warm mix asphalt – but the haul was much longer than usual.”
Smith says warm mix was stored in a silo overnight so it was ready for transport early the next morning. She says temperature out of the silo was between 280 and 285 degrees F when it was loaded into the haul trucks, which were then tightly tarped for the journey over the water, then driven onto the ferry. Ferry trips took 90 minutes and the ferry trip of each day carried a six-person paving crew, equipment and the warm mix.
Smith says mix in the trucks that came over on the first ferry waited as long as 4 ½ hours from load to laydown while the crew prepared the pavement. “The crew came over with the equipment and the first load,” she says. “Initial prep work was done in advance, the final preparation was done once the material and crew arrived.”
Smith says warm mix placed from the early trucks that sat longest was placed at about 250 degrees F, but after the first ferry trip Miozzi scheduled the loads so three trucks arrived at the jobsite every two to 2 ½ hours. “As the day went on and the prep work was minimal, the haul was more like 2 ½ hours and mix was placed at 270 degrees F,” Smith says.