UMD asphalt studies paving the way to better roads

FALL RIVER — Down a long hallway at the glossy UMass Dartmouth Advanced Technology and Manufacturing Center on Martine Street lies a laboratory where asphalt is king.

The laboratory is the work of civil engineering professor Dr. Walaa Mogawer, who for the last quarter century has been building the capability and reputation of the place among highway engineers nationwide.

To say Mogawer is passionate about asphalt understates the case. “I love the smell of asphalt more than roses,” he joyfully told a visitor to the room in the lab where asphalt samples were being prepared for testing.

The lab had much of the appearance of a kitchen, except that the concoctions being stirred in the metal pans weren’t brownies but some combination of new asphalt, recycled asphalt milled from the surface of the nation’s highways, recycled rubber and recycled asphalt roofing shingles.

It is the latter that occupy Mogawer’s mind these days, since his laboratory won a $249,785 grant from the New England Transportation Consortium to study ways of reclaiming the asphalt roofing shingles that are routinely stripped from houses and dumped into costly landfills.

The asphalt industry in general has been very recycling-minded in recent years, and Mogawer explains why: It’s the price of oil, and the value of petroleum products locked up beneath our feet (or our vehicle tires).

Long gone are the days of 99-cent gasoline and similar prices for everything else that comes from crude oil. Now with oil prices four times that or more, and millions of miles of the nation’s roads paved with asphalt, recycling is compulsory.

“There’s a treasure there,” said Mogawer about the shingles and the pavement. “Why are we throwing it away when we can mill it and reuse it?”

There is much more to recycling asphalt than simply throwing some recycled material into the cauldron along with the “virgin” ingredients that haven’t seen a road surface yet. There are matters of durability, elasticity, and “rutting” by tens of thousands of vehicles’ tires over the same spot.

Mogawer and his student assistants spend countless hours preparing batches of asphalt pavement with varying ingredients, baking them in ovens to bring them up to the typical temperature of hot asphalt. The cooled-off cylindrical samples that emerge from the molds are drilled for core samples and analyzed in any number of ways.

One device rolls over the asphalt sample as if it were a passing vehicle, pushing the material to its failure point within about a day.

Other instruments record what it takes to bend and break a sample of experimental asphalt material. At another work station, samples are subjected to the stress of expanding and contracting in varying climate conditions.

Asphalt, as it happens, is more complex than simply mixing together some sand, rocks, and other ingredients with an asphalt glue, boiling it up at close to 400 degrees, and letting it cool and harden.

The climate where it is to be used matters greatly, said Mogawer. Roads in Texas, for example, require a stiffer surface, something that will resist high temperatures. A highway in Maine will need special attention given to expansion and contraction as the seasons change.

That poses a challenge for the reuse of asphalt or of shingles, Mogawer said. After being exposed to the elements — sunlight and oxygen — for 15 or 20 years, asphalt shingles become extremely brittle, which can be problematic.

As urgently as the industry and government want to recycle shingles to save money and improve the environment, it will take labs like Mogawer’s to determine what recipes, what asphalt concoctions, will do the job as well or better than the materials now being used, and save money in the bargain.

Some of those experiments are under way in the town of Dartmouth, where large sections of Tucker Road were recently repaved using an asphalt formula evaluated by UMass and designed to save money while matching the performance of conventional asphalt formulas.

Dartmouth is one of a number of towns — and states — that have come to Mogawer for analysis of what it is they are putting down on the roadways.

But Mogawer is frustrated that more municipalities aren’t coming to his lab for the free services he provides in quality control testing of new or rebuilt roadways.

Mogawer cites a statistic when he talked about recycling our roadways: Only 1 to 2 percent of the asphalt being produced today goes to the construction of new roads. All the rest, he said, goes into rebuilding existing roads.

That is something the asphalt industry touts as being a strong advantage. Asphalt roads can be milled and repaved over and over again for decades, with the materials being reused to a greater and greater extent.

Mogawer, meanwhile, pushes the envelope with research looking into not only asphalt shingles but recycled rubber, which he said can improve the elasticity of the asphalt mixture. The problem is that there are few suppliers producing the powdered rubber that the lab needs to incorporate into the formulas that it is testing.

Elsewhere, experiments continue on using new additives to recycle asphalt. Mogawar cited a failed experiment in Illinois and North Carolina. “They used swine manure and added it to the asphalt. “The smell was awful,” he said, “and it stuck to their clothes.”

While that failed, other experiments are under way to produce warm temperature asphalt, up to 100 degrees Fahrenheit cooler than traditional formulas. Warm asphalt uses less energy (to heat), is easier to work with, emits less fumes, and can be applied during a longer season.

Mogawer said that his lab produces civil engineering graduates that, should they be interested in pursuing a career in paving material science, are quickly snapped up by the small number of labs like this one nationally.

And he remains a devotee of asphalt, even as innovations emerge, such as tempered glass solar panels that are being touted as a revolutionary paving material. “They’re all good ideas, but they’re not easy to implement,” he said. For the next century or so, he said, asphalt is still the way to go, still king.