On-Site Concrete Crushing And Recycling

By Zoie Clift | September 28, 2010

With rising costs and landfill space at a premium, combined with new technology and equipment hitting the market, more contractors are starting to hone their sights on recycling.

A highway job currently taking place in Arkansas is a case in point.

The crushing and recycling measures are being unleashed on a $42.3-million expansion of U.S. Interstate 67 at 167 in North Little Rock and Sherwood. The project has been implemented in an effort to ease traffic for motorists. Plans call for removing and crushing the existing concrete pavement and reusing it for the new road. Over the course of the project, about 107,000 cubic yards of concrete will be removed and around 220,000 cubic yards added, reusing almost everything on the job along the way.

Plans are to use the crushed pieces as sub-base gravel for the new road. This gravel will be used as the bottom layer of the road, giving the road its strength. Because of the size of the crushed material, it's not suitable for use as the finished surface for the roads. In reusing this concrete as sub-base gravel, rather than using new gravel that would need to be purchased from another source, thousands of dollars are saved by taxpayers.

"A lot of people don't realize how much recycling we do, but we try to reuse as much as we can." said Don Weaver, vice president of Weaver-Bailey Contractors Inc., based in El Paso, Ark., one of the general contractors of the project. Concrete work has been both a niche and the foundation for the firm, and the company is one of the largest concrete pavers in the state.

The job, which is being done by a portable crusher off-site but near the highway, started in mid-June. After a few days of getting things oriented and in working order with the machine, efforts are now progressing smoothly. Weaver said there will be two sections to the ongoing crushing portion of the project. Work on the first phase will last around three months. Contractors will then come back next March to crush for a few more months.

The Hwy. 67 project entails widening a 5.2-mile section of highway, which was built around 40 years ago, from two lanes to three. The route currently handles around 80,000 cars a day, and was built for probably around 30,000 less in mind. The project also calls for adding one-way frontage roads and repaving existing roads. Also in the works in association with the deal is an $11-million subcontract to Muskogee Bridge Co., out of Muskogee, Okla., which will do work on four bridges. Work on the job broke ground around half a year ago and is expected to finish around March 2008.

During the early stages of the project, which was awarded by the Arkansas State Highway and Transportation Department, Federal Highway Administrator Mary E. Peters visited the site, commenting on installed technologies the project incorporates that will both save money and make the road more durable, such as longer-lasting concrete and maintenance-free steel beams.

As a material, concrete is the most widely used construction material in the world, and the highway industry is the nation's largest recycler of the material. According to Royce Bradley, co-owner of Bradley Contracting Inc., which is headquartered in Cord, Ark., and has been contracted to crush the material on the 67 job, the key to the recycling route lies in the cost-effective measures it produces. Bradley said recycling concrete from demolition projects such as this can save money, such as that needed to transport concrete to a landfill as well as for the cost of disposing it. He added that not only isn't there a need to pay to have debris hauled away, but the end product becomes "free" material to use in new construction. It also cuts down on added congestion that the transportation would cause, which makes the construction zone safer for the public.

"It saves money on trying to go back out here and gravel again and put it down and then also pay to get it disposed of," he said. Bradley said if one looks at Little Rock, Fayetteville, and some of the other bigger cities around the state, they will see they are starting to outgrow their limits and are running out of landfill space. "As much as Arkansas is doing now repairing, rebuilding roads like 167, you are looking at a major disposal site," he said. "And looking at major disposal costs to go to a landfill ... No landfill is going to take this. It's too much."

The introduction of portable crushers has not only eliminated the removal of asphalt and cement, it has also axed the need to bring in aggregate to serve as a base material for new roads and other development needs.

The machine chosen for the Hwy. 67 job is the 55,000-pound ST 352 mobile screen, specifically designed for quarrying, construction and recycling jobs and catering to work that requires high production, fine screening and multiple products. The unit is composed of mobile crushing and screening equipment and uses SmartScreen technology that is housed with an IC300 intelligent controller. This controls the startup and shutdown process of the crusher, and remote and radio controls are also provided, enabling workers easy movement around the job site.

The system is part of the Lokotrack ST series and is the first to have the SmartScreen technology installed. The unit links the mobile crushing and screening process together with a control system. Via this controller, the system is able to supervise and automatically adjust the entire unit, providing benefits such as higher production, increased efficiency and easier operation. The result is a reduced need for manpower. By controlling both the feed rate and screen performance, the machine is able to efficiently maintain screening through the entire crushing process. The system can also be linked with other Lokotrack crushers and mobile screens and is transported via a conveyor folding mechanism.

The unit was provided by Metso Minerals Industries Inc., a worldwide supplier of rock and mineral processing equipment with headquarters in Waukesha, Wis. Scott Equipment Company LLC, which sells and rents construction equipment throughout Arkansas, Louisiana, Mississippi, Tennessee, and Texas, served as their distributor.

As landfill costs for construction, demolition and land-clearing debris continue to rise, and the landfills become more heavily regulated, Bradley said it makes sense to seek alternative means of disposal of concrete from construction and demolition operations. He said he has noticed that more disposal sites are opening up and contractors are incorporating recycling into their operations to decrease disposal costs. "Basically it's economics." he said. "You can make cheaper product than by going down to a granite mountain and buying it."

"It's catching on," added Blake Lanier, who also works for the crushing division of Bradley Contracting, Inc. Lanier said there has been a trend on recycled jobs in association with federal highway projects. "Everybody is thinking the federal government is going to start requiring more and more recycled concrete on jobs with federal money. So this is going to become more popular in the future."