Indus Uses Bio-based Fogseal to Prove Rejuvenation

When a contractor can show the merits of a plant-based pavement preservation strategy, it’s a win for the whole community.

By Sandy Lender

TThe picturesque, island community of Nantucket, Massachusetts, includes nearly 30 miles of bike paths that the Department of Public Works (DPW) is responsible for maintaining.* Way back in November 2020, DPW hired BETA Group Inc., based in New England, to assess the island’s bike paths, which resulted in a Pavement Preservation Capital Improvement Plan (PPCIP). As part of that plan, BETA Group reported, the town would see two phases of improvement on its bike paths—a crack sealing phase and an asphalt rejuvenating fogsealing phase. The town’s contractor, indus, went a step above and beyond for the town when it came to implementing the fogseal.

“A unique part of the project was the aesthetics,” said Alan Viall, a regional manager for indus. “This is a traditional island. They like the old, weathered look. They don’t like the black crack sealing.”

Because Viall understood the mindset of the community and could assess the pavement before work was to begin, he had the opportunity to advise DPW and BETA. “Indus had been contacted to look at 21 miles of bike paths for crack sealing purposes,” he explained. “This third path [Madaket] was a perfect pavement preservation candidate to use the Delta Mist.”

Delta Mist is a liquid, plant-based penetrating asphalt spray rejuvenator from Collaborative Aggregates LLC (CollAgg) of Lowell, Massachusetts, which indus has applied to preservation projects since 2016. The product goes down as a white, almost opaque spray, but once dry, it leaves a transparent “seal” over the pavement that doesn’t require the contractor or agency to restripe pavement markings. By using Delta Mist, indus would be able to preserve the pavement while leaving Nantucket’s old-fashioned look intact.

“I had a Zoom call with the DPW director and the town’s consultant, and I explained the process,” Viall said. “They liked the idea.”

What Viall and team provided the Nantucket community was more than what industry refers to as the “right treatment on the right pavement at the right time.” They provided the right product on the right pavement at the right time. Here’s how they protected the Madaket Bike Path on Nantucket Island with Delta Mist.

The town handled communications with the homeowners along the pavement to be treated in early September 2021, but all members of indus crews know their product is a human safe and environmentally safe, plant-based rejuvenator that won’t stain or mar landscaping features. When tourists or residents have questions, indus crewmembers are able to answer their questions and set the public at ease. But Viall has found a few extra steps can help keep the public from walking up to an active work zone—they cover catch basins and grates before spraying, even though their product poses no danger to waterways.

*The https://www.nantucket-ma.gov/ website lists eight bike paths, which tourist sites agree total about 30 miles on the island.

The liquid, plant-based Delta Mist penetrating asphalt rejuvenator from Collaborative Aggregates LLC, Lowell, Massachusetts, sprays white but cures transparent in up to 60 minutes, depending on ambient conditions, which means pavement markings remain visible. All photos courtesy of John Giammatteo

The crew couldn’t drive the distributor truck across the footbridge due to weight concerns. Instead, they used the hand wand to apply the fogseal to the pavement because the plant-based Delta Mist alleviates any environmental concerns, Alan Viall explained.

LEFT: Viall describes the Delta Mist as having a very natural scent, similar to linseed oil. RIGHT: When bystanders ask questions, indus crewmembers explain that Delta Mist is a plant-based product.

“What we have found is that we cover every catch basin to alleviate any worries of the residents. It’s not so much protection as it is a way to avoid unnecessary concerns.”

With the pavement swept and blown free of debris and dirt, the crew covered the catch basins. The material is applied at ambient temperatures, so the crew could easily use a hand wand to take care of edge work.

They used their E.D. Etnyre 3,000-gallon distributor truck to spray 7 gallons per minute—or 0.055 gallons per square yard. This rate falls within the 0.05 to 0.135 gallons per square yard that CollAgg recommends, based on the pavement surface condition. Viall had personally assessed the pavement of the paths, finding no heaving or structural problems that would indicate subbase issues, thus he felt comfortable allowing the 26,000-pound distributor truck to drive on the path.

“The town uses trucks to plow the pavement during the winter,” he said, indicating the base held up to more abuse than their truck offered.

Spraying on a sunny day with a light breeze allowed the rejuvenating fogseal to dry within 30 to 60 minutes and allowed foot and

LEFT: A unique aspect of the Madaket Bike Path project was retaining an old, weathered look to the pavement. Delta Mist’s transparent coating provided the solution with no add-ons like sand or aggregate coverings. RIGHT: The crew cleans the pavement in preparation for a rejuvenating fogseal.

bike traffic back on immediately. “It was perfect weather,” Viall said. “If someone was riding 300 to 400 yards behind us, they were fine.”

The goal of applying a rejuvenator to the pavement surface is to revitalize the surface binder, which can potentially extend the lifetime of the pavement. That’s what Delta Mist penetrating asphalt rejuvenator is designed to do. It penetrates the top 3/8 inch of the surface pavement and slows the oxidation of the asphalt binder. It minimizes the loss of fines and aggregates, giving the binder the opportunity to hold the aggregates for a longer time, offering a longer service life to the treated pavement. And that’s what Nantucket DPW wants.

In fact, Viall said, the department is pleased with the project and interested in applying it to mainline roadways in the future.

By end of the day, the Nantucket community had a preserved pavement for Madaket Bike Path, sealed against the elements, looking as good as old. And the town had proof of an environmentally friendly technology providing a transparent surface treatment for future pavement preservation work.