When the 320-degree material gets placed at night, ambient temperature can start to play with your workability.
For P&S Paving, Daytona Beach, Florida, knocking the production temperature down to the 270-degree range can be the answer. They include Evotherm warm-mix asphalt (WMA) additive from Ingevity of North Charleston, South Carolina, in all their mixes, and the practice has come in handy during the 14-mile Interstate 95 (I-95) project in Florida, specifically.
I-95 spans almost 2,000 miles up the east coast of the United States.
382 miles of I-95 are in Florida.
Director of Quality Control Tim Carter explained, “Everything at P&S Paving has Evotherm in it. I’m a big proponent of M-1.” The team’s experience not only with the use of additives, but also with quality production and paving practices, has brought them success implementing in-house quality control/quality assurance (QC/QA) and getting excellent numbers on the I-95 project.
The Florida Department of Transportation (FDOT) reported that general contractor Archer Western Construction, Chicago, began the design-build project on I-95 in 2014. The project includes widening and realigning a section of the interstate referred to as International Speedway Boulevard [U.S. 92] as well as systems interchange reconstruction. The asphalt paving falls under the jurisdiction of subcontractor P&S Paving, including sections P&S subs out, to the tune of 140,000 total tons on the project, plus over 30,000 tons in temporary lanes.
One aspect of the ongoing project is planning for the future, and that included raising Bellevue Bridge to accommodate a future train right-of-way.
The I-95 Project Team at FDOT, under the direction of FDOT Project Manager Christopher Briggs, P.E., shared: “The Bellevue bridge height increased 5 to 7 feet higher than the previous bridge. The height depends on where it is measured from. Now that collector distributor roads are being added, the bridge also lengthens as well. The I-95 bridge over U.S. 92 where the potential alignment for the future rail might go was raised 5 feet. The minimum height requirement from the roadway for the future rail line is 23.5 feet.”
Carter explained that while paving up to the raised bridge, the paving crew encountered and overcame the challenge of nighttime temperature fluctuations. The FC-5 mixture specified for the project is an open-graded friction course, to shed water, with a PG82-22, to resist rutting.
“PG82-22 mixes are also one of the most sensitive designs in terms of temperature, so the window of opportunity to properly seat the stone is very limited,” Carter explained. “When Evotherm is added to the mix, it provides additional workability time to address issues as they arise, such as the removal of any deleterious materials on the mat.”
For the crew placing the 1.5-inch surface course on the ramps to the newly raised Bellevue Bridge, nighttime temperatures and dew provided the workability challenge. Carter explained the production temperature of the mix was hitting 315 to 320 degrees F. If the ambient temperature is in the 60s, FDOT allows contractors to keep paving, but when ambient temps drop, FDOT wants contractors to stop in the name of quality. Carter’s team at the plant took the production temperature down to the 270 degree range, which is a benefit of using a warm-mix asphalt additive such as Evotherm.
Sources spoke to the addition of Evotherm for in-field performance. In this case, the warm-mix additive is functioning as a compactive aid and increasing the time for compaction.
Even with good materials, ambient temperatures in the winter of 2017 and early 2018, after busy tropical seasons, gave the team pause.
“Fortunately this winter’s cold weather has impacted the overall progress of the project only in a small way,” the project team reported. “The project is so large that we are able to work on various activities not dependent on warmer climates. With good planning, hard work and a little bit of luck, the completion of the southern portion of the project was achieved prior to the winter. The open graded friction course, which requires higher temperature for its installation was laid prior to November. Now the focus is on completion of limerock base and structural asphalt on the north portion of the project. The anticipated project completion has shifted to the fall of 2018 due to the compounded effect of rain and added work.”
The good news is Archer Western, P&S Paving and Halifax have kept communication and quality top of mind throughout the rainy or cold seasons.
“Despite having had two consecutive years with hurricane impacts to the project, the progress has been great,” the project team reported. “The 9-mile section of I-95 from SR44 to just south of I-4 has been reconstructed to accommodate a third lane in each direction and has been opened to the traveling public since October of last year.
This would not have been possible to achieve so soon without the excellent communication and coordination among Archer Western, P&S Paving and Halifax Paving. Archer Western completed four key bridges and drainage along the corridor, while P&S Paving and Halifax Paving worked on completing the roadway portion.”
Carter confirmed P&S Paving’s crew performed the paving on the 10.5 miles from S.R. 44 to south of I-4 that were completed by November 2017. “P&S is the primary sub-contractor responsible for all of the paving but it should be noted that we use an additional contracting firm to provide the paving for portions of the project as well but they do fall under our umbrella of paving responsibility for the project.”
Carter’s QC team places a priority on quality from start to finish. That means mix design and testing in the lab is serious business.
Lab QC Manager Edward Madigan and Roadway QC Manager Carleton Dobbins came to P&S Paving with Carter about three years ago when the company brought testing in-house. Carter shared how their in-house team attitude shapes day-to-day jobs.
“Carleton will make sure the three roadway QC techs have the training and tools they need, but he doesn’t micro-manage them. Ed manages the three lab QC techs. Those guys really make things happen in the lab and on the roadway in real time. They make decisions in the moment. Their teams are all responsible for keeping quality fine-tuned.”
Carter shared that the QC team encourages innovation and ideas, but only adopts a new idea if it’s something they can implement across the board. “Consistency is a mantra,” he said. “If it was a good idea at another company, we might adopt it here, but we’re going to do it the same way and make it right.”
For the I-95 project in particular, getting quality “in a hurry,” is one objective.
Carter explained that the paving crew often has short paving sections on the I-95 project, and may have more than 30 days before the next section is to be paved. With a 30-day time limit on the percent-within-limits (PWL) program, that means pay factors are based on short paving sections.
“It’s important that we stay consistent in those short windows,” Carter said. “The pay factors on the project were gradation, texture, spread rate and liquid binder content. With spread rate restrictions in particular, there is a high probability of texture issues because you’re laying the asphalt so thinly. So it’s important that the stone coats well and stays put quickly. This is where Evotherm really helps. We just don’t see any tenderness, pushing or shoving of the asphalt.” The spread rate was specified at 83 pounds and the liquid binder content was 6 percent.
P&S Paving’s commitment to quality shows on the I-95 project’s numbers, as reported by the FDOT Project Team: “During projects, the department has measures in place to award or deduct, from the quality of the asphalt left on the project,” the project team reported. “We want the best quality asphalt that we can get. So we have a scale that measures asphalt called the CPF (composite pay factor). The CPF goes from 0.95 to 1.05 with 1.0 being the middle point. As the contractor makes and places the asphalt, they get a CPF on that asphalt; now anything below 0.99 to 0.95 is a deduction (still acceptable asphalt) and 1.0 is no deduction or award, and anything above 1.01 to 1.05 is an award for having asphalt above the middle point. P&S has pretty much been above the 1.0 CPF for the project, which shows their dedication and ability to perform. The project has performed and produced good, quality work and asphalt that is a true reflection of the project team wanting and trying to perform higher than just average.
The project’s mindset is to doing it right the first time and produce the highest quality product that we can.”
P&S Paving’s management took the time to slope and pave the area beneath the stockpiles to facilitate moisture runoff. The water is collected in a ditch that feeds into a pond onsite where the conservationist in me was delighted to watch a blue heron hang out for sunset.
The asphalt facility planning team has done more than provide a peaceful setting for the regional wildlife. They’ve made it possible for the wheel loader operator, Chris McGuire, to get clean, dry material fed to the plant. From a point at the base of the cold feed bins all the way down through the stockpile to the back curb, there is six feet of fall. At the back curb, runoff is collected in the ditch and redirected out to the pond area.
McGuire also feeds RAP to a fractionating plant from KPI-JCI to get sized material for high-percentage RAP mixes. At this time, the plant has two RAP bins—one is calibrated for coarse material, one for fine. The plant is rated to run up to 65 percent RAP, according to Carter.
Even incoming liquid material is offloaded with gravity’s help. When delivery trucks arrive, the drivers pull onto an 18-inch tall “speed hump” so the tanker is resting on an incline. The tanker offloading island makes the pump’s job a little easier when filling up a tank at the farm. Carter said the Heatec calibration tank at the tank farm lets them calibrate any liquid at any time. “Blending Evotherm at the terminal prior to shipment also makes it easy to use and ensures that every drop of liquid receives the proper dosage for maximum consistency. We get paid for consistency, so I do everything I can to get paid the most.”
Design with Asphalt in Mind
The FDOT Project Team spoke to the efficiency of the team and process on I-95. “Speed of delivery of this project is impressive. This I-95 project was bid using a Design Build delivery method, and as a result of it a firm with design and construction capabilities was hired to reconstruction 14 miles of I-95 from SR 44 to just north of US 92. The bid includes every aspect necessary to complete this project with the exception of purchasing the necessary Right of Way.
In Design Build contracting the firm makes the design decisions that fit their strategy and proceeds with early construction basically compressing the schedule. As part of the Design Build selection process, the firm offered to use a PG82-22 binder in the top lift of structural asphalt and FC-5 on the I-95 travel lanes. This binder selection will help toward having a longer pavement life. During the reconstruction process, a 10-foot paved shoulder was maintained to allow breakdown vehicles to pull off the travel lanes….Half of the paved shoulder’s width was temporary and RAP material was used for its base cutting down on cost. The temporary paved shoulder definitely had a positive impact on motorist’s safety and their ease of travel. Design Build is highly recommended for larger projects that need to be completed in the shortest time possible.”