Since Feb. 1, 2015, the Florida Department of Transportation (FDOT) and public-private partnership group I-4 Mobility Partners (I-4MP) have been paying ongoing attention to mounds of concrete, steel, asphalt and wood during its I-4 Ultimate Improvement Project.

The project involves reconstructing 21 miles of roadway in both directions through Central Florida, including 15 major interchanges, 140 bridges and four variable-priced toll express lanes.

In addition to building the new roadway, I-4MP also will operate and maintain it for the next 40 years. A joint venture construction firm within the I-4MP, known as SGL Constructors, is performing the work.

“This project will bring the interstate, which was built in the 1960s, to meet current industry standards and better accommodate the number of vehicles traveling on the interstate today,” Brook Brookshire, SGL project director, says. “Both the driver and passengers will benefit greatly. The driver will realize greater reliability, reduced travel times, better traffic flow and improved visibility, while passengers will enjoy an enhanced aesthetic experience.”

Without the I-4MP, the I-4 Ultimate project would take approximately 17 years longer than its scheduled 2021 completion, say those involved. According to the I-4 Ultimate website, public-private partnerships such as this one allows the parties to split risks and rewards between them, including funding and accelerating the construction schedule.

“Overall, this is the largest and most complex infrastructure project underway in the state of Florida today,” says Matt Baumann, Alexandria, Virginia-based construction firm and SGL member Skanska’s I-4 Ultimate project environmental compliance manager.

But reconstructing an expansive amount of highway isn’t the only end game for the I-4MP. Sustainability during reconstruction is just as important, it says. So far, more than 100,000 tons of wood, concrete, asphalt, steel reinforcing rods, paper and plastics have been recycled, with the number growing every day.

“[21 miles] is a lot of roadway to complete in six years,” Baumann says. “Cutting down the entire environmental footprint is a big plus.”

CUTTING COSTS AND EMISSIONS

Sonny Glasbrenner Inc., Clearwater, Florida, is the demolition subcontractor for the project.

Once Glasbrenner crews demolish a section of the road, the materials are taken to one of the two processing yards on-site. Once enough materials are stockpiled, Crushing Inc., Casselberry, Florida, crushes the concrete at SGL’s material yard.

Ken Herron, owner of Crushing, says the company put a bid on the Ultimate I-4 project in 2015 and was officially awarded the contract in April 2016 for as much as $2.3 million, depending on the amount of concrete it crushes.

Herron says the crew has a goal of crushing at least 1,000 tons of material per day for the project, but the exact amount will be determined at the end of the project through an electronic belt scale on its stacking conveyor.

Crushing uses a GT4400CC track-mounted crushing and screening plant and a 36-by-80-inch radial stacking conveyor from Kolberg-Pioneer Inc. (KPI), Yankton, South Dakota, to get the concrete down to a 1½-inch-minus product that meets FDOT specifications.

Herron says the exact specification is kept confidential by SGL, but it calls for a specific graduation and load bearing ratio, and his material is tested on a weekly basis. “The required FDOT specification is tough to make, but we have worked on this specification on other projects and have learned all of the trade secrets.”

Crushing crews load 15-inch-minus material, prepared by SGL, into the crushing and screening system with a Komatsu PC-360 excavator. A vibrating feeder brings the prepared concrete to the impact crusher.

The crushed material is then conveyed on the vibrating screen, where it’s sized to a 1½-inch-minus material.

The sized material is then conveyed to its stacking conveyor for stockpiling. Remaining steel or rebar from the concrete is removed by magnet.

Excavators, front-end loaders, demolition hammers, crushers and milling machines by various manufacturers, including Peoria, Illinois-based Caterpillar; Moline, Illinois-based John Deere; and Volvo Construction Equipment, with U.S. headquarters in Shippensburg, Pennsylvania, also are being used to process and recycle road materials on-site.

Asphalt is milled from the roadway and taken to the project’s processing yards for reuse. Mulch and other wood generated from clearing activities is used for soil stabilization, but if it isn’t a fit for on-site use, it is sent to be reused as mulch at landscaping companies or as biofuel.

This, according to Baumann, allows FDOT and the I-4MP to cut down on costs and any further emissions that can be produced by hauling the material to an off-site location.

“It’s easier, there’s a shorter haul,” Baumann says. “There are two locations within the project limits where material is processed for recycling or reuse.”

Baumann says the team has already reached its 99 percent recycling goal.

According to Baumann, environmental protection isn’t the only benefit of processing and using recycled materials on-site—cost also comes into play.

“You don’t have to go after and seek virgin materials,” he says. “We are taking the old road and it’s becoming part of the new project.”

RELFECTING THE BEST

For the state and its partners, one goal set for this project was to qualify for the Envision program, a rating system by the Institute for Sustainable Infrastructure that rewards projects for their sustainability efforts and the environmental, social and economic impacts on the communities in which they are located.

In January 2017, the I-4 project was awarded Envision’s Platinum qualification—the highest possible within the program.

Baumann says project partners made a commitment for the Envision certification during the bid and proposal stage of the project, and it has taken the team two years to meet the requirements and obtain the award.

Baumann says air emissions were part of the award, including using equipment that complies with the U.S. Environmental Protection Agency (EPA) Tier IV engine emissions standards. “We purchased 90 percent of the equipment so it meets Tier IV air emissions by the U.S. EPA, ” Baumann says.

FDOT is interested in pursuing more Envision qualifications in future projects, which Baumann says also hopefully will further the state’s interest in using recycled materials in future projects.

The author is assistant editor for Construction & Demolition Recycling and can be contacted at hcrisan@gie.net.