Edited by Loren Faulkner
Intermountain Slurry Seal overcame darkness, heavy traffic, and strict working and environmental requirements to place a micro-surface — a new wear surface with greater skid resistance — on 15 miles of U.S. Route 76 just north of San Diego. The Utah-headquartered company applied micro-surfacing to 254,118 square yards of roadway, using a Bergkamp Inc. M1 Continuous Paver.
"[Public] agencies are better off taking care of their best roads first," said Rusty Price, general manager of Intermountain Slurry Seal's Utah branch.
"The whole concept behind preservation is putting the right treatment on the right road at the right time," he said. "It saves you a lot of money in the future. Preservation costs $2–3 per square yard, while a 4-inch mill-and-fill costs about $15–17 per square yard. You can preserve the pavement twice in the time that you would mill-and-fill once, and save tremendously."
Intermountain Slurry Seal worked closely with Caltrans to complete the project on time. The California area operations managed the project by working with Caltrans, traffic control and pavement-marking subcontractors on scheduling and contractual agreements, while the Utah operations used its equipment and crew to lay the new surface. Caltrans had specified that this micro-surfacing job must be handled using a continuous paver. Bergkamp's M1 continuous paver was chosen because, when used with mobile support units, it lays material for long distances without stopping — reducing construction joints.
The U.S. Route 76 project was located within the Pala and Pauma Indian Reservations. "Route 76 still had its original chip seal surface that was placed about 10 years ago and was starting to show signs of raveling and aging," said Price. "The micro-surface improved the quality of the highly traveled road and protected it against further deterioration."
Intermountain Slurry Seal's crew could work only between 9 p.m. and 6 a.m., Sunday night through Friday morning. The job consisted of sweeping off the 15-mile road, fog sealing the shoulders, and removing all of the striping and reflective pavement markers. Then the crew micro-surfaced 13-foot-wide paths in each travel lane.
"Micro-surfacing is very challenging at night, and honestly there was more traffic on the road at night than during the day," said Price. "We could only control two miles of the road in one lane at a time, so we would often bump up our traffic control to stay within those regulations."
With as many as 1,000 cars on the road at one time during work hours, Intermountain Slurry Seal emphasized safety. Daily safety meetings were held to eliminate danger to both the workers and oncoming traffic. There were no accidents during the job.
Intermountain Slurry Seal finished the project ahead of schedule despite using an aggregate source it had never used before. The Type III aggregate — received from Coachella Valley Aggregate in the Palm Springs area — was put through extensive testing. In order to be classified as Type III, a specific percentage of the aggregate had to successfully pass through eight different-sized screens.
"We use a 1,000-gram sample of the aggregate and run it through the screens, weighing it before and after to see if the end product meets specification," said Price. "Type III aggregate is a 'beefier' product than Type II and is the most common aggregate used for highways and other large projects."
Intermountain Slurry Seal uses five ingredients in the micro-surfacing mix:
- Polymer modified emulsion (65- percent asphalt, 35-percent water and emulsified chemicals)
- Type III aggregate
- Mineral filler (Portland cement, hydrated lime or other chemicals)
- Additives (optional, used at opera tor's discretion for break control)
Bergkamp's M1 continuous paver has a separate compartment for each of these ingredients. At the flip of a switch, the ingredients are delivered at metered rates into the pug mill, where they are mixed and transferred to a hydraulically adjustable, variable-width spreader box. The augers in the spreader box spread the mix throughout the box and onto the road. Mobile support unit trucks hold replacement ingredients and feed the paving machine when it runs low, keeping the machine running constantly and minimizing the number of construction joints in the road.
In all, Intermountain Slurry Seal used the following to complete the project:
- 2,287,062 square feet of Type III micro-surfacing
- 3,081 tons of Type III aggregate
- 381 tons of micro-surfacing emulsion
- 800 90-lb sacks of Type I cement
- 16 tons of concentrate fog seal
Intermountain Slurry Seal also took extra environmental precautions to prevent the leakage of asphalt or chemicals into the environment — including laying down tarps to absorb excess material during cleaning.
The company is a wholly owned subsidiary of Granite Construction Company. Chip seal and micro-surfacing make up 65 percent to 70 percent of the Utah operational area's business, with 25 percent in slurry seal and the rest in fog seal and rejuvenation work. Recent California work includes six miles of the Yosemite National Park El Portal Road in California.
Note: Eric Pulley is a marketing coordinator with BMG company, Fort Wayne, Ind.