Saugerties Tests New 6.3 mm Polymer-Modified HMA

Thu December 01, 2005 - Northeast Edition
Construction Equipment Guide

On Oct. 4, 2005, Peckham Road Corp. applied a 6.3-mm hot mix asphalt surface treatment to Rivka Road for the Town of Saugerties Highway Department.

Saugerties Highway Superintendent Bernie Ellsworth had been looking to do a demonstration project with this product since the spring of 2005. The road that he chose was a low volume road that was used by residents for commuting. Normally, a single-coarse liquid asphalt chip seal would have been called for, but the road also was used by walkers and bicyclists. Ellsworth knew that the maintenance treatment used would need to provide pedestrians and bicyclists with a smooth, dense, screed laid surface for minimal cost. The 6.3-mm mix met these requirements perfectly.

“It is a thin lift asphalt overlay material developed by a task force made up of both industry and agency personnel. This product went out this year with good acceptance by DOT [Department of Transportation], towns and counties,” said Bruce Barkevich, of the New York State Construction Materials Association.

The 6.3 mm hot mix is designed as an alternative to micro-surfacing or paver placed surface treatments (NovaChip). It is applied on both low- and high-volume roads needing a maintenance treatment. It is designed to be applied at a 1 in. depth. It has been approved for use by the New York State Department of Transportation (NYSDOT) when applied in accordance with its specifications.

Peckham Materials Corporation has a hot mix plant in Catskill, NY and when it was looking for a candidate road for a trial application, the fit with the Town of Saugerties was perfect.

The 6.3 mm Superpave hot mix asphalt was designed by Peckham’s in-house quality control staff. The 6.3 mm uses a special polymer modified asphalt (PG-64-28E). The asphalt is engineered to meet standard PG-64-28 specification but in addition it contains elastic polymers that give it greater flexibility and adhesive properties.

It is well suited to the thin lift asphalt content asphalt tack coat during construction. It is critical that the tack coat be used to minimize the chance of the thin lift 6.3 mm mix delaminating from the old pavement surface below. The polymer modified asphalt combined with the Superpave mix design and high asphalt content tack coat help to eliminate problems normally associated with thin lift hot mix pavements.

“Bernie did a little different process because he didn’t use the concentrated tack. This was an agreement between him and the HMA supplier. This will be a good chance to see how this application works together,” said Barkevich.

Once the design was in place and the road selected, the construction was planned. The Town of Saugerties, using its own forces, shimmed the road to bring it within its geometric specifications. Since this was a new application for Peckham, it was decided that the best practice for construction of the 6.3 mm mix would be to use the Peckham Road Corp. paver and crew.

Because of the nice job done by the Town of Saugerties crew in shimming the road, the Peckham road crew was able to apply a consistent 1-in. lift to the road. A Blaw-Knox PF3200 paver was used for construction and a Hamm DD110 roller was used for compaction. A single roller was used since the trial section involved only approximately 350 tons of material and the paving speeds were controlled so that the roller could easily keep up with the paver.

There were no production issues at the plant except that a tank had to be isolated for storage of the PG-64-28E liquid asphalt. Nor were there any paving or compaction issues that were encountered during paving. The Peckham quality control staff performed testing on the 6.3 mm mix during production.

The cooperative effort between Peckham and Bernie Ellsworth and the Town of Saugerties Highway Department made this trial pavement possible. In addition, several neighboring towns supplied trucks for the paving operation and sent representatives to view the operation. The participants included: the Town of Ulster Highway Department Superintendent Donald “Mac” Tinnie; the Town of Woodstock Highway Department Town Superintendent Michael Reynolds; and Ulster County Department of Highway and Bridges Commissioner Dave Sheeley and Field Operations Manager John Lukasewski.

The trial was a success and it brought a new maintenance alternative to the Hudson Valley region of New York State.