Road Worthy

Probably one of the greatest market opportunities for C&D recyclers remains
the roadbuilding industry. Already, products such as recycled concrete, asphalt,
wood, fines and asphalt shingles are used in roads in various regions of North America.

But C&D recyclers of all stripes have said that the toughest segment of that market to enter is the highway market, where concerns for quality and a reluctance by government agencies to make changes to what has worked in the past have slowed the influx of recycled products to this sector.

That is changing, albeit slowly, according to officials at the Federal Highway Administration (FHWA), the U.S. agency that works with state Departments of Transportation on developing and maintaining the country’s highway system. However, barriers and prejudices to recycled products remain, although the economics are starting to make recycled materials look more attractive. Here is a look at what is happening at the state level, from the viewpoint of the FHWA.

Need Is There. "We are in the process now, and will be for the next two decades, of rebuilding American’s infrastructure," says Byron Lord, deputy director, Office of Pavement technology, FHWA. "We are talking about hundreds of billions, if not trillions, of tons of material out there. And it would be great for us to use every bit of that in rebuilding the system."

That is what is happening in much of Europe already, according to a scanning study sponsored by FHWA and the American Association of State Highway Transportation Officials (AASHTO). The objective of the scanning study was to review and document innovative policies, programs and techniques in Europe. Recommendations would then be made that would lead to reduced barriers to recycled material use in the United States.

What the study participants found was a pervasive culture of recycling in several European countries that have found ways to use recycled materials while maintaining the quality of their highways. The study concludes that the U.S. government should follow the Dutch model of sustainability. (To read about the significant level of recycling taking place in Europe, go to http://international.fhwa.dot.gov/pdfs/recycolor.pdf.)

Reluctance. But in the U.S. state Department of Transportations are still greatly reluctant to use recycled concrete as aggregate, among other things, reports Charles Luedders of the FHWA’s Denver office. He is in charge of the Recycled Concrete Aggregate Federal Highway Administration National Review. The purpose of the review is to capture for technical deployment the most advanced uses of recycled concrete aggregate and then transfer the knowledge to all state transportation agencies (STA).

That reluctance, says Luedders, is because of a perceived inconsistency within the product. Most concrete recycling operations crush everything that comes in, and state highway engineers are concerned about the quality of the aggregates that made up the original concrete—whether there was air entrainment, perhaps alkali silica reactivity problem, etc. "Now, when they can control the sources of concrete," he says, "they are not quite as reluctant to use it."

But Lord says the highway engineers’ reluctance is understandable because of the tremendous amount of responsibility they have for the public good. "As you move into the realm of the uncertain, you go with great caution because you have great responsibility. If you don’t know, you don’t do."

But FHWA seems to be embracing recycled materials as the future of highway construction. Recently the agency announced a new recycling policy, "Recycling and reuse can offer engineering, economic and environmental benefits. Recycled materials should get first consideration in materials selection. Determination of the use of recycled materials should include an initial review of engineering and environmental suitability.

"An assessment of economic benefits should follow in the selection process. Restrictions that prohibit the use of recycled materials without technical basis should be removed from specifications," the policy reads. The FHWA has set up a Web page (http://www.fhwa.dot.gov/pavement/recycle.htm) to show off some of the work done at the federal level to promote recycled materials.

Lord, who has been a proponent of proper recycled material use for many years, says he seeing a "real evolution" by the corporate side of the highway industry as it recognizes the value of recycled materials and embraces them as profit centers. "We are seeing more and more where contractors are incorporating recycled materials into their product streams, just like virgin materials."

Part of the evolution is a greater understanding of what is a recyclable material. "Ten years ago people were given waste and asked to figure out how to use it in their systems," he says. "We believe highways are not a waste disposal system. We are looking for quality materials to build America’s highways with. These quality materials, wherever they come from, must meet the engineering, economic and environmental considerations."

But Lord admits there are barriers to recycled materials. "Our role is to identify the barriers, identify if those barriers are inappropriate, and develop the information and supporting justification to aid those who put those barriers up because they believe they are necessary."

Ammunition. FHWA’s national review on recycled concrete is only one arrow in that quiver. Luedders has gathered technical information on the engineering characteristics of recycled concrete, and says there are some factors that are better with recycled concrete when compared to natural aggregate, such as a lower coefficient of thermal expansion. He also cites a project he has been following since 1990 that used recycled concrete as concrete aggregate. He recently examined the road and found only one transferous crack on the project. "On most highway projects, you would find way more than that," he says.

Material specifications are a barrier to recycled concrete’s use in highways. Lord says a lot of those specifications were developed on limited knowledge, relying on "traditional values in which we have a great deal of confidence because they have continued to deliver over the years. I am not saying they are wrong. They came about for good reason. When we change them, we have to make sure what we are changing them to still continues to deliver what we need."

One positive step toward furthering the use of recycled aggregates in highways may be a switch to performance-based and performance-related specifications for materials. "The challenge is to identify what is the performance element and characterize it properly, such that flexibility is given to allow whatever they want to use with those performance elements," Lord says.

Superpave, the material selection and mixture proportioning system developed a few years ago for building high-quality highways, is one program that has changed to allow for the use of recycled materials. When Superpave was originally formulated and implemented, there was little room for recycled materials in the process. "But that has changed," Lord says. "Many people have worked to find ways to use recycled materials in the system, particularly recycled asphalt. Now lots of states use recycled asphalt mixes designed using the Superpave system."

Lord remains bullish on recycled material use in highways. "We have it in our vision for the future that we will be able to close our own material cycle. As we rebuild, we have to have ways to use everything. Yes, some things will not be suitable for reuse, and we want to minimize that as much as possible. We want to be able to help our partners, the state DOTs that will be doing the work, to understand how that works, to understand what they can do and when they can do it."

The author is associate publisher of Construction & Demolition Recycling magazine and executive director of the Construction Materials Recycling Association. He can be contacted at turley@cdrecycling.org.