Middlesex forgets about foam

Dec 04, 2017

If you’ve landed at Orlando International Airport or driven on one of the interstate highways in Florida, then the chances are quite high that you’ve ridden on asphalt pavement placed by the Middlesex Corporation. Middlesex is headquartered in Littleton, Massachusetts, and has offices in Connecticut and Florida. The company has been around since the early 1970s and is a definitive leader in the paving industry, ranking among the Engineering News Record’s top 400 list of contractors in 2016.

Prior to 2014, the Middlesex division in Orlando, Florida, was a big fan of foaming with HMA. But then they won the bid for a job in the City of Casselberry that specified the use of WMA and everything changed. Middlesex went from not using any WMA in 2014 to using almost 1 million tons per year by 2017. Today, 100 percent of the company’s Orlando-division paving is done with Ingevity’s Evotherm® WMA technology. Middlesex is now one of the single largest plant producers of Evotherm in the southeastern U.S. What’s behind this dramatic transition?

In early 2013, the City of Casselberry developed its own specification for WMA (CASB 334), based on the Florida Department of Transportation’s (FDOT) specification but tailored to better suit projects of the size and nature of the local government. This made the city the first in the state to require the use of WMA instead of HMA for its large public road rehabilitation projects.

The city’s first project using this WMA specification in 2013 was a milling and resurfacing area of approximately 8 miles. In a June 2016 blog post about the City of Casselberry, we spoke about their award-winning, city-wide sustainable paving program that mandates the use of WMA. Why the WMA mandate?

Consulting engineering firm VHB needed a product that could act as a liquid antistrip and a WMA technology. They knew Ingevity’s Evotherm to be a reliable alternative to HMA with foam and were pleased that Middlesex created such a successful end-product with the additive.

“One of the biggest hurdles that newcomers to warm mix have is getting mix temperatures down,” explained Jason Mapes, technical services manager at Ingevity. “Part of the value that our technical services team provides to customers is helping their crews understand how to lower temperatures in order to build the correct cohesion in the mat that will allow it to withstand the stresses of the paver and the rollers.”

How was the transition for Middlesex’s crew? “We were able to work with the crew and the plant to lower temperatures by about 40 degrees,” reported Mapes. “We made some adjustments to roller speed and rolling patterns that then enabled them to achieve density without any issues. Middlesex liked seeing how these relatively simple changes made a big impact to the overall outcome of the project. A positive impact.”