Macadam and Chip Seal Combo Gets the Job Done Right

By Joanne Ray | September 28, 2010

Combining the chip sealing process with macadam proved to be the answer to getting the job done right at Webb Memorial State Park on Route 3A in Weymouth, MA.

Recently, Riverside Asphalt Services was contracted out to install a New "Macadam" system access way at the park. The area is owned by the Massachusetts Dept. of Conservation & Recreation under a contract to Clean Harbors, Inc.

"This project was part of a multimillion-dollar remediation effort by Conoco-Phillips Petroleum," said Paul Fulmore from Riverside. "The people that owned it before owned it when it was OK to pollute, but then the state of Mass. came in and said, 'You have to fix this now.' There was a lot of dirty dirt there, and they had to dredge up part of the harbor and truck the stuff away to a site somewhere. They must have had 25 to 30 laborers each day taking out the hazardous waste. At first they thought the cleanup was going to cost about $100 million but it ended up being somewhere around $55 million."

Fulmore said this project encompassed a combination of macadam and chip seal.

"We had to incorporate the macadam with the chip seal to make sure that the job got done right," Fulmore said. "The site had problems, and there was a lot of recycled contaminated soil. There use to be some kind of glue factory there. We used macadam on the areas that were not paved and chip seal over the existing pavements."

Fulmore said macadam was the right choice for the non-paved areas because the park area has the potential to shift by a small amount.

"The beauty of using macadam is that the system is pliable and won't crack versus a hot asphalt mix, and it looks nicer," Fulmore said. "You're controlling the product in the end. And the idea is that when the project is done, the area has to look the same as it did when the project was started."

The macadam process dates back to the 19th century, when inventor John Loudon McAdam pioneered his technique as a replacement for dirt roads. John McAdam, who was born in Scotland in 1756, was raised working in English road construction. After several decades of work, McAdam published two in-depth reports on the need for an improved road system using layered rocks. In 1816, as the surveyor on Bristol Turnpike, McAdam tested out his process for creating roads, called macadamizing.

The original system used for macadam roads involved a triple layer of stone. The bottom two layers were comprised of hand-broken rocks laid to a depth of 8 inches (20.3 centimeters) over a formation level called a sub-grade. The top layer had smaller rocks no more than 2 inches thick. The entire road was then compacted and crushed together by use of an enormous roller. In addition, macadamized roads had a slightly convex shape, so that water would run off into drains on either side, rather than collecting on the road.

The macadam process became popular throughout the world, particularly in the quickly expanding American Northeast. On roadways, tar-bound macadam used a layer of tar on the sub-grade and bound the layers together during rolling with sand and tar. Many early airports used tarmac pavement around the terminals, leading to the modern usage of the term for the disembarking area around a plane.

Fulmore said his use of the macadam process was much the same on this project when his crew put down 1-inch stone on a prepared base (processed gravel) and then saturated it with MC 3000 liquid asphalt. Then the crew added a smaller layer of crushed stone followed by liquid asphalt and then more crushed stone.

During the chip seal process, trailer dumps from supplier P.J. Keating deposited about 500 tons of 1-1/2-inch, 3/8-inch and 3/4-inch stone. Keating also brought in about 300 tons of stone-dust that came in on 15 trailers to spread on the paths.

"We had to put in walking paths," Fulmore said. "They get a lot of foot traffic down there. The art of this whole project was that when the project was done, the area would still look the way it was before the project started."

During the process, the asphalt used was an MC 3000 cutback that was heated to 305 degrees Fahrenheit and applied at the rate of 1/3 gallon per square yard for chip seal and two gallons per square yard for macadam. At least 10,000 gallons of glue or liquid asphalt were used.

Fulmore said the project took two years from start to finish. Riverside had five laborers working on the site on any given day.

The equipment used included a 635 Leeboy grader, DD23 Ingersoll Rand compactor, 8500 Leeboy paver, three Mack dump trucks, one Mack Etnyre distributor asphalt tanker, one Komatsu 3-ton roller, and up to three Gehl skid steers.

Fulmore said the project used a combination of 1,000 square yards of chip seal and macadam and used about 10,000 yards total.

"We probably used $75,000 to $100,000 in materials by the time the project was finished," Fulmore said.