Good Density Equals Smoothness Bonus
Mayo Construction Inc., headquartered in Cavalier, North Dakota, took on a set of three projects that amounted to one large mill-and-pave project for the state Department of Transportation (NDDOT), placing 166,818 tons of HMA from early August to late October 2022. Despite liquid asphalt cement (AC) delivery challenges, the team completed 82 lane miles in 50 days of paving with no corrective grinds required by the owner. They garnered over $350,000 in bonuses. Here’s how they did it.
Plan for Success
After winning projects 23151, 23377 and 23580 along a 37-mile stretch of Highway 52 for NDDOT, Mayo Construction hired Bryce Wuori as the project manager to assist in the completion of the company’s largest construction project in the almost 100 years of operation. Wuori brought a number of tools along, including the Pavescan® RDM 2.0 device from Geophysical Survey Systems Inc. (GSSI) and his proprietary Pavewise software system. The Pavescan assisted in quality control/quality assurance (QC/QA). Mayo Construction has also been using the Willow notched wedge system over the past construction seasons to achieve joint density on required projects.
Mayo President Trevor Christianson said, “As a company we try to stay on the cutting edge of technology to be as efficient and successful as possible. I truly believe our crews pave some of the best roads in the state and we are proud of this accomplishment.”
As of April 2019, the Pavescan RDM pavement density measurement technology is an accepted American Association of State and Highway Transportation Officials (AASHTO) specification, PP 98-19.
“Trucking logistics issues and taking advantage of the best paving days for the echelon paving and mainline paving were key in the success of the ride and density on this project,” Wuori said.
The team had an average of 50 trucks per day from 15 trucking companies on the project. The peak was 70-75 trucks from hired subcontractors and owner/operators. Needless to say, it took special coordination of all activities, from the full project width milling, to trench milling for the purpose of correcting existing rutting, to 139,438 tons of aggregate base from two pits with two subcontractors for passing lane construction, to echelon paving after trench paving.
“We also planned operations around scheduled rain days. Since this project was over 30 miles long, we were able to work on certain parts of the project even if it was raining on one end and not on the other end. These types of decisions produced in conjunction with data from Pavewise helped us be as efficient as possible with the paving days we had on the project.”
The team also had to be efficient in light of binder delays.
Christianson explained that the asphalt mix—the state’s Superpave FAA 45—was a good design. “The state wanted a virgin asphalt mix design,” he shared, stating it required a PG58H-34 liquid binder.
He praised the plant crew, saying they produced the mix consistently; it gave the field crew no issues with compaction or otherwise. “One of the struggles on the project was consistently getting shipments of AC to the site,” Christianson shared. “Since this [liquid] came from Canada, there were transportation and border crossing restrictions that would fall out of our control on the project.”
Wuori explained, “We did have to shut the project down multiple times because of lack of AC. An extra holding tank was added to the project to keep more AC available.”
Solving that inconvenience, crews received mix at temperatures averaging 315-330°F, depending on the weather. “We did start adding an Evotherm in late October,” Wuori said, to take advantage of the additive’s cool-weather paving properties. He explained the state allows operations to continue with lower temperatures when additive is used. “The first asphalt plant location was approximately 16 miles away from the paving operations and the second asphalt plant setup location was 26 miles away from paving operations.”
Mill, Fill, Ride Smooth
“There was approximately 130,693 tons of milling reclaimed on the project,” Christianson said. “Most of the milling was done with a 12-foot mill or a combination of a 12-foot mill and an 8-foot milling machine.”
Three sites accepted excess millings for two local owners. At the peak of production, the crew had five portable scales on site to monitor material.
And as material was taken away and the profiled surface was cleaned and tacked, the paving crew made ready for the finish. The Superpave mix would be placed at a depth of 2 inches compacted, across the width of up to 38 feet, depending on location along the project. Belly dumps delivered mix in windrows ahead of Cat and Weiler pickup machines. Those transferred material to Cat pavers paving in echelon on six passing lanes to eliminate the longitudinal joint.
Christianson said the paving team used a Cat screed extensions kit to stretch the paver out past 20 feet wide on parts of the project. “We used best paving practices for the joint, including Willow Notched Wedge.” He proudly shared the DOT required not a single corrective International Roughness Index (IRI) grind on the lane miles of paving on entire project.
Wuori explained, “We had the Willow device running on the longitudinal joint and a custom-built sluff roller on the outside edge. It works very well and mounts to the outside of the screed gate in about two minutes with two workers installing it. It does have to be managed with a release agent and adjusted every once in a while.”
To achieve compaction, the team used one consistent rolling pattern for most of the mainline paving and Wuori double-checked that with the Pavescan GPS device, sharing the data between management and the paving team. They started with a double drum steel CB16 in the breakdown position, followed by two intermediate rollers. The first was a double steel drum Dynapac roller, then a rubber tire CW-34. A double drum steel roller performed finish. “Typically for joint density we set it in place with knockdown and then pinch with rubber tire roller. These roller operators are all veterans and exceptional in their skills.”
The results were bonus worthy.
Christianson shared the stats: “There were approximately 82 lane miles of paving on the project. The 20-foot-wide paving average IRI was a 32.2. The 18-foot-wide paving was a 34.5. There was not a single corrective grind on the entire project required by the owner. The average mat density on the project was 93.4% and average joint density on the project was 90.9%.”
It’s not just the IRI that brought the accolades for Mayo Construction.
“The final bonus produced on the project from ride, joint density and mat density incentive was approximately $350,000,” Wuori said. “The project also beat its bid estimates for production and profits as well.”
That kind of success doesn’t sneak up on a crew. Wuori was the consultant running the Pavescan and seeing the numbers coming up day in and day out. He could tell something special was happening.
“We had a really good couple weeks where we were doing 25,000-30,000 tons a week in paving along with 10,000-20,000 tons of gravel placed in a week,” Wuori said. “It was the end of September when everything was clicking good.”
“The Mayo team did an amazing job from project management to field operations,” Christianson said. “It was a team effort that shows what kind of success we can produce as a company when we all work together and put our minds together on a common goal.”
The Mayo Construction website spells out a commitment to its workers, stating its quality of work is only as good as the expertise of its employees. The company offers a variety of insurances for workers and states, “We’re dedicated to ensuring all our employees are properly trained and feel confident in their abilities to successfully, and most important, safely complete their job duties.”
When Wuori integrated the Pavewise platform with best practices as a project manager on the Hwy. 52 project, this combination of tools gave him the opportunity to monitor the health of a handful of flaggers and pilot car drivers during the arduous project. This proved advantageous when a few workers were experiencing burnout and conflicts with other employees and needed assistance.
“I had the responsibility of managing up to 20 flaggers and pilot cars daily on this project and was able to use the software as a tool to help manage what teams worked well together and who was struggling with the team they were currently on. The software also assisted with managing the locations of where the flaggers and pilot cars needed to work on a day-to-day basis as construction operations changed daily.
“Having a digital platform that keeps you connected to employees’ daily energy and health is very important and makes the project much more efficient and safer for everyone. These are the people with the boots on the ground making the project a reality and they are more important than anything else on these projects.”
Christianson echoed the importance of the workers for this project’s final success, saying it was “a combination of a highly skilled milling team, paving team and rolling team that follow best paving practices and understand the importance of consistency in the field.”