Two stretches of Wisconsin's STH 133 in Grant County now provide a safer and much improved travel surface for motorists using the road between Muscoda and Boscobel thanks to the quality warranty pavement work executed by Mathy Construction this past summer.
Mathy served as the general contractor on the $7.5-million project, which required full removal of the old asphalt surface, grading and reconstructing a new aggregate subbase, and the placement of a new Type E-1 hot-mix asphalt overlay.
Wisconsin Department of Transportation awarded Mathy the warranty contract, which required the contractor to install orange safety fence and temporary "Native Prairie" signs along portions of the project to prohibit work activity within an adjacent Department of Natural Resources' designated protected prairie environment. Any topsoil salvaged from areas along the designated prairie environment had to be stockpiled separately from other topsoil, so that it could be returned to the prairie areas during final grading of the adjacent right-of-way.
Although stipulations of the warranty contract required Mathy to stand behind its work for five years after completion of the final surface lift, it also proved beneficial to both WisDOT and the contractor. The contract eliminated the usual jobsite testing (core sampling, documented temperature readings, density compaction testing, etc.) as well as much of the mix production testing required by WisDOT, and it also allowed Mathy the flexibility to design the project's mix. The only stipulation WisDOT imposed on mix design was that it conformed to its Type E-1 specification (which is considered a Superpave design). The 2.5-inch base course mix design consisted of 45-percent 19mm limestone aggregate, 15-percent manmade sand, 20-percent natural sand and 20-percent reclaimed asphalt pavement (RAP). The 2-inch surface course mix design consisted of 12.5mm limestone aggregate with the same quantities of materials used in the base course design, with the exception of RAP (only 10-percent RAP content was used in the surface course). Both mix designs contained 4.8-percent of performance grade (PG 58-28 for base course mix and PG 64-22 for surface course mix) liquid asphalt cement binder, with some adjustment made based on the binder content of the RAP additive.
Prior to construction, Mathy provided WisDOT's project engineer with a quality control plan outlining the contractor's material and construction control processes. The plan included a list of the quality control tests to be used in controlling the material and construction quality. It also included sampling, testing and documentation frequencies, as well as the HMA pavement job mix formulas (JMF) planned for the project and the method used to develop the JMF. At the completion of the project, Mathy is required to provide documentation of the project to the state's engineer.
The contract required Mathy's Quality Control/Quality Assurance lab testing procedures to pull a sample from the mix produced every 1,000 tons. Mathy pulled a sample every 800 tons produced and conducted tests (in its portable lab at the production facility) to monitor gradation, absorption and compaction characteristics of the mix sent out to the project.
"We only conducted verification testing approximately one in 10 samples the contractor tested," notes Scott Lowry, WisDOT project manager.
All documentation required at completion of the project will include all quality control test results and any changes made to the project's typical widths and depths of subgrade, subbase, base and surface. That documentation will be used when evaluating the pavement's performance over the five-year warranty period.
Distress types to be monitored during the five-year warranty include alligator cracking, block cracking, edge raveling, flushing, longitudinal cracking, longitudinal distortion, rutting, surface raveling, transverse cracking, transverse distortion, patching, pothole and slippage. The contract clearly defines the remedial action required to fix any of the distress types that may occur during the warranty period. Warranty work to be performed by Mathy on this project consists of remedial work, elective/preventive maintenance, and the required fourth year crack routing and sealing.
Fairly smooth delivery
According to Andrew Marinelli, P.E., Mathy project manager, work on the highway was executed without any signficant problems. There were some delays earlier in the summer completing the aggregate subbase and waiting for the City of Boscobel to complete sanitary sewer and water main facilities through the project, but Marinelli anticipated that all HMA placements would be completed on schedule. Mathy's Iverson Construction division had 165 days in the contract to place the 70,000 tons of HMA required to construct the new two-lane highway.
"We began working on the project in April by milling off the old asphalt overlay," Marinelli says. "We completed that phase of the project in three weeks, and then we brought in subcontractors to do a scratch grading of the subbase, expanding the existing 12-foot-wide travel lanes to 17-foot-wide lanes (to accommodate a paved shoulder/bicycle lane). The project required some vertical realignment, but no horizontal realignment.
"About the only significant challenge we've faced on this project has been in areas restricted by the protected prairie grass lands," he adds. "We had to install miles of silt fence and we could only push off topsoil so far to avoid encroaching on those designated protected areas. We also hit one silty/sandy area that we had to excavate and rebuild, but otherwise the subbase was in very good condition."
But once Marinelli's paving crew arrived on the project, they picked up the pace by averaging well over 4,000 tons placed per day. They actually set a Wisconsin production record for one portable plant supplying a single paver on August 3, placing 7,643 tons in one day. The crew was equipped with a Terex Cedarapids 452 paver with a Cedarapids material transfer device attached on the front.
That allowed for non-stop paving and eliminated any truck contact with the paver. Compaction was achieved with a Dynapac steel-drum breakdown roller, followed by a Dynapac pneumatic-tired roller and another Dynapac steel-drum roller for finish.
The paving crew was supplied by one of Mathy's portable plants, a Bituma 400-tph (tons per hour) parallel-flow facility, which was set up near the west end of the project.
All other work on the project — striping, grading of the gravel shoulders, landscaping and signage was handled by subcontractors.
With more road agencies awarding more warranty work, contractors like Mathy have more control and flexibility in how they deliver a quality project and road agencies are able to reallocate their resources where needed.
Lowry, who has been with WisDOT for the past 15 years, says he expects to see more future projects awarded as warranty contracts.
"It (warranty contract) allows us (WisDOT) to make better use of our resources," Lowry says. "We can allocate our field technicians to projects where they are needed and let contractors monitor their own work on projects like the Hwy. 133 project we just completed. For two-lane state highways like 133, the warranty approach makes a lot of sense for us and the contractor doing the work."