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Public Roads - July/August 2000

Lessons Learned: TxDOT's Efforts to Increase The Use of Recycled Materials

by Rebecca Davio

"Why should I read this article?" you may be thinking. "Using recycled materials isn’t my job. That’s for someone in the environmental section to worry about." Maybe your job is overseeing road construction or maintenance, maintaining the mobility of people and goods, or ensuring a safe transportation infrastructure. Very well, but isn’t part of your job also to identify the best quality materials and to stretch your budget by identifying the materials offering the best value?

Recycled materials can be a source of good-quality, cost-effective road materials that also benefit the environment. Using recycled materials can frequently improve materials performance and lessen raw materials shortages. Using recycled materials may cut costs because materials costs may be less than for new materials; transportation/delivery costs may be less; and disposal costs for job-site materials may be less. And, using recycled materials benefits the environment by extending the life of limited natural resources, reducing air and water pollution, and extending landfill life.

Crushed concrete, reclaimed asphalt pavement, glass, brick, compost, and other recycled materials can successfully be used as substitute aggregates in road construction.

According to the U.S. Geological Survey (USGS), more than 330 million tons (300 million metric tons) of crushed stone were used in road base during 1996. The mining of such stone, however, is "increasingly being constrained by urbanization, zoning regulations, increased costs, and environmental concerns."1 In some parts of the country, the supply of local stone has been exhausted, requiring long hauls and higher prices.

Using recycled materials in road construction offers opportunities to use huge quantities of recycled materials while extending the supply of traditional construction materials and ensuring good-quality roads. The USGS calculates that even though the use of recycled crushed concrete aggregates increased by 170 percent between 1994 and 1996, it still constituted only 0.4 percent of the total aggregates consumed in 1995.2

The Texas Department of Transportation (TxDOT) initiated a program in 1994 to encourage the use of recycled materials in Texas road construction and maintenance projects. TxDOT has learned a great deal from its five-year initiative to use more recycled materials, and although these lessons are presented from the perspective of a state department of transportation (DOT), the ideas also apply to local road and bridge departments.

The lessons are presented in seven steps. TxDOT’s experience is provided for each step.

Step 1 — Designate a Point-of-Contact

Designate someone to be responsible for collecting and disseminating information about recycled materials to the many players in the road construction industry. This person will help provide focus for a program that will span the many aspects of transportation operations — from bituminous pavements to traffic safety devices to right-of-way vegetation. This point-of-contact must be the recycled materials champion. This person does not necessarily have to be an engineer, but he or she must be comfortable analyzing technical information and must communicate well. The full support of top department managers for this person’s efforts is also a requirement for success.

The TxDOT Experience

At TxDOT, four people are working full-time to advance recycling and the use of recycled products and to get the message out to 14,500 department employees, the Texas contracting community, and the state’s local road-building partners. The four are the program manager, a communication specialist, a specialist in data gathering and analysis, and a Geographic Information System (GIS) analyst.

In addition, a statewide network of part-time construction and maintenance recycling coordinators (CMRCs) serve as the incoming and outgoing communication contact for their region regarding recycled roadway materials. CMRC responsibilities are typically fulfilled by the director of construction or director of operations in each district. Headquarters engineering-related divisions also designated CMRCs. (This network of CMRCs is in addition to the regular recycling coordinators who typically work in an office or warehouse setting and help promote TxDOT’s recycling program.)

Step 2 — Assess the Situation

Scour your internal tracking systems for information regarding the quantity and types of traditional materials used in construction and maintenance projects. These quantities represent the total materials demand and will establish the baseline. These data are sometimes difficult to get for the entire state, but estimates may be available from your DOT materials staff or directly from suppliers. Some information may also be available from USGS.

Next, it is necessary to gather information about the available materials supply. The supply is made up of two components: traditional (virgin) materials and recycled materials. Information about traditional materials sources may come at the same time and from the same source as the usage information. It would be very helpful to know the expected supply life of these sources although these data may be very difficult to obtain because of their proprietary nature.

Information about the potential supply of recycled materials may come from as many sources as the recycled materials themselves. Recycled materials can come from the municipal solid waste stream (i.e., glass or tires), from industries (i.e., fly ash from utility plants), or from agricultural sources (i.e., compost). Your state environmental protection agency and trade associations may have data about the types, volumes, and sources of recycled materials.

The materials demand data should be compared with the supply data. By understanding the availability of traditional aggregates, sands, and other construction materials within the state, it should be possible to identify regions where there are materials shortages. It will be easier for recycled materials to gain a competitive edge in these areas because they may offer a significant cost advantage due to shorter transportation distances.

The TxDOT Experience

TxDOT approached this step backward, by focusing first on the availability of recycled materials. There was an anecdotal understanding that certain areas of the state had no native aggregates, but there was not a readily available source of data about materials usage throughout the entire state. The department conducted a survey of some of Texas’ largest manufacturers to learn about their recyclable materials with potential in road construction operations. TxDOT also surveyed its existing materials suppliers to determine if they were willing and able to process recyclable materials.

This data was fed into a Geographic Information System (GIS) to facilitate an analysis of the supply of recycled materials for the entire state. A GIS, sometimes referred to as a "smart map," links tabular data to a graphic image. This is a powerful tool that can simplify data analysis and significantly increase the insights. Each type of data is displayed as a different layer. By combining layers on a single map, one can see, for example, where a recycled material generator is located near a company that can process the material to meet the specifications. By overlaying upcoming construction projects, TxDOT can identify the potential demand for these recycled materials. Knowing where recycled materials are located will help the department to direct people to materials actually available in their region at a reasonable cost.

Much work remains in this area. TxDOT needs more data about the state’s traditional materials usage volumes and sources of municipal wastes with potential for use in road construction. This information will help the department to identify where recycled materials can help address material shortfalls. Adding information about the quality of traditional materials will also show where recycled materials can offer alternatives to poor-quality native sources.

Compost, shown here being applied with a manure spreader, helped establish right-of-way vegetation where numerious previous efforts had failed.

Step 3 — Identify Competitive Recycled Materials

A great deal of research has already been done on many recycled roadway materials through organizations such as the Federal Highway Administration (FHWA), the Recycled Materials Research Center, the Transportation Research Board (TRB), the National Cooperative Highway Research Program (NCHRP), state DOTs, and industry associations. This research can take many forms: synthesis reports; laboratory work; or, in many cases, local demonstration or pilot projects.

Research should strive to identify recycled materials that offer promise. Recycled materials, like most new products that compete in the marketplace with entrenched competitors, have to offer an advantage. The new recycled products can frequently gain a competitive advantage by solving problems.

A prime example is recycled plastic manhole adjusting rings. To visualize these products, picture brown, stackable, Hula-Hoops. These products, despite their unusual appearance, offer many advantages over the traditional manhole-adjusting rings made of concrete. The recycled plastic rings are lighter in weight, which makes them safer for workers to transport and install. They are less fragile than the traditional rings, making them less likely to get broken during transport, and the plastic rings are strong enough to withstand the pressure of vehicles driving across them. This is an example of a recycled product with superior engineering performance, a life-cycle cost advantage, and environmental benefits.

To identify competitive products, research should begin by verifying the engineering properties of recycled materials. Recycled materials must meet or exceed existing engineering standards to be usable. Fortunately, though, there is a wide array of recycled materials that not only meet the standards but actually exceed them. Many times, recycled materials offer performance advantages not attainable with virgin materials. Compost, for example, not only provides soil nutrients necessary for plant growth along highway rights of way, but it also improves soil texture and water-holding capacity in ways that traditional fertilizers cannot.

Engineering standards are key, but the analysis also has to address the environmental quality of recycled materials. Even recycled materials generators, who have the most to gain economically from finding markets for their materials, want to ensure that the materials are being used correctly. An environmental quality requirement is comforting to DOT engineers, road construction workers, contractors, environmental regulators, and recycled materials generators.

In addition to engineering and environmental quality, recycled materials for use in road construction must also be cost-effective. Research and demonstration projects can help determine this as well. Recycled materials must be available for a reasonable cost. However, the definition of the term "reasonable" varies. In some instances, it means the same price as the corresponding traditional material. Sometimes it means much less expensive. This kind of big cost differential is especially important until the material has proven its usefulness. In some cases, the price of the recycled material may be reasonable even if it exceeds the price of the traditional material because the recycled material provides superior performance.

The TxDOT Experience

In Texas, the slogan used to convey the value of recycled materials is: "Recycled roadway materials work. They’re good-quality, cost-effective, and good for the environment." The order of the benefits is purposeful. Environment considerations are very important; however, the initial evaluation of the use of a recycled material must focus on the engineering quality and the cost-effectiveness of the material. Otherwise, the use of recycled materials will never be sustainable.

TxDOT holds recycled materials to the same engineering standards as traditional materials. A recently completed environmental specification outlines the steps that must be taken to ensure environmental quality. This specification requires that recycled materials be compared to traditional materials and that any supplemental legal reporting requirements and documentation be addressed. (Refer to

A number of demonstration projects have been conducted throughout the state. These projects helped build partnerships on the local level and offered an opportunity to invite other participants to gain first-hand experience.

Step 4 — Formulate a Plan

Use the data collected thus far to develop a plan. The structure of the plan is not nearly as important as making a list of goals with the strategies to achieve them. The plan may identify geographic locations or particular construction applications (i.e., roadbase or embankment fill) that show great potential. Another option is to focus initially on a small number of the most promising recycled materials.

When formulating the plan, do not overlook other groups that can help achieve the goals. There are many national industry associations with state chapters that can supply information and assistance to promote the use of recycled materials.

The American Coal Ash Association (ACAA) is an example. ACAA promotes the use of fly ash and bottom ash produced when coal is burned to produce electricity. ACAA conducts research, sponsors workshops, and provides other services.

Also, engineering universities will likely be eager to conduct research and help with implementation.

The TxDOT Experience

TxDOT developed a "Roadway Recycling Strategic Implementation Plan" with specific goals and the action steps necessary to achieve them. This plan provided some structure to the department’s recycling efforts and allowed everyone to understand the game plan. (TxDOT’s plan can be viewed at

TxDOT’s goal is to increase the use of recycled materials where they yield engineering or economic advantages and environmental benefits. The four steps to achieve this goal are to: (1) modify specifications to allow for the use of recycled materials; (2) conduct pilot projects to verify the engineering, economic, and environmental benefits; (3) facilitate a consistent supply of high-quality recycled materials; and (4) communicate with members of the road construction industry and recycled materials generators.

One of the groups that was identified as a powerful ally in efforts to increase the use of recycled materials was the Texas Chapter of the Associated General Contractors (AGC). AGC formed a recycling committee to inform contractors about recycled materials.

Step 5 — Develop a Tracking System

If possible, use existing management information systems to track the quantity of recycled materials used. Perhaps, no existing systems can track this information. If not, at least track the use of certain key materials. Without a clear method to estimate the volume of recycled roadway materials used, it is impossible to quantify the benefits of recycling or evaluate program accomplishments.

Ideally, the system should be able to track the volume of materials used, dollar savings, and environmental benefits. This type of information is critical for evaluation purposes, preparing management reports, and applying for awards. These measurement systems should attempt to look at life-cycle costs. For some recycled materials, the up-front cost is higher, but the maintenance and replacement expenses drop significantly. An example is plastic lumber. Plastic lumber is made from plastic or from a combination of plastic and wood fibers. It comes in the normal dimensions for lumber and can be worked with regular woodworking tools. It will not crack, splinter, rot, or be bothered by termites. Once it is installed, it is virtually maintenance-free for years, significantly lowering the lifetime costs.

The TxDOT Experience

TxDOT is currently developing a comprehensive tracking system for recycled roadway materials usage. Contractors are required to report the type and quantity of recycled materials used on their jobs if they want to qualify for a reduced "retainage" amount. (Retainage is a specified percentage of authorized payments that is withheld, as a kind of insurance policy, until the job is satisfactorily completed.) This will be the most comprehensive source available to TxDOT regarding the types of recycled materials used on state projects. Prior to the development of this system, the department primarily tracked the usage of fly ash, glass beads, and tire rubber.

TxDOT tracked the recycled materials used on nine demonstration projects, and the totals were amazing. More than 20,000 tons (18,000 metric tons) of materials were beneficially reused on these projects, keeping 2.4 pounds (more than a kilogram) of material out of the landfill for each person living in Texas.

Step 6 — Create a Level Playing Field

Recycled materials may inadvertently be put at a disadvantage by specification language. Specifications are the gatekeepers for recycled materials. Begin by reviewing road construction specifications for words like "virgin" and "naturally occurring" that obviously prohibit recycled materials. A more subtle specification barrier is one that expresses the requirements in such a way that only traditional materials can compete. For example, a guardrail post blockout may require that each blockout contain a specified number of annual growth rings per inch. Recycled plastic blockouts cannot measure up to a standard stated in this manner.

Another way to create a level playing field is to eliminate environmental barriers. For example, a legal stigma is associated with the term "wastes." Some state environmental agencies have established a mechanism whereby certain wastes can be reclassified as non-wastes, co-products, or beneficial uses to reduce the time, expense, and legal liability of using recycled materials. A specification that addresses environmental quality for recycled materials — providing a clear understanding of what is allowed and what procedures have to be followed — can be very desirable, as long as it does not hold recycled materials to standards that no traditional, virgin materials could reach.

It is important to remember that using recycled materials generally does not require changing everything. In fact, it is better to make the fewest changes necessary. The most successful recycled materials will probably not require a change in standards, procedures, or equipment because they can be substituted one-for-one with the traditional material. For example, if recycled roofing shingles can be added to hot mix in the same way as reclaimed asphalt pavement, there is no need for new equipment or procedures. The goal should be to make using recycled materials as easy as possible.

One way to ease into using recycled materials is to try pilot projects on low-volume roads. It is important to

Glass cullet (small pieces of crushed glass) is available from many communities' recycling programs and can be used in roadbase, as it was in Abilene.

install control sections where traditional materials are used under the same circumstances. It is also important to assign someone to collect, tabulate, and evaluate the pilot project results. Road construction personnel frequently do not have the time to take these extra steps. If nobody does, then you will get very general feedback (e.g., "That stuff worked pretty good, but it cost a lot more.") when specific, quantified feedback (e.g., "We achieved a 50-percent improvement in performance for a 10-percent higher initial price.") would be much more useful.

Mandates that force engineers to use recycled materials in every project are not the solution that they may appear to be to some. While mandates have potential, they also have their negative aspects.

The federal Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA) illustrates this point. ISTEA was lauded as landmark legislation that would, among other things, single-handedly solve the scrap tire problem in this country. This law required the use of crumb rubber in hot-mix asphalt pavements, and it imposed severe financial penalties for noncompliance. There was so much opposition, however, that the crumb rubber mandate was ultimately repealed. This mandate did not significantly increase the amount of crumb rubber used, and in some areas, it had a very detrimental effect on the perception of crumb rubber.

An alternative method to encourage the use of recycled materials and to help create a level playing field is to offer incentives. Look for incentives that do not dramatically increase costs.

The TxDOT Experience

TxDOT developed draft specifications allowing for the use of recycled materials. Then pilot projects, endorsed by the district engineers to reduce the perceived risk for the local engineer, were used to field test the specifications. Other steps that TxDOT took to make it easy to use recycled materials included providing recycled material samples, compiling research results that compared recycled and traditional materials performance, and identifying sources for the recycled materials. In Texas, engineering colleges helped monitor the pilot project results and were responsible for modifying the draft specifications to prepare them for use statewide.

One incentive being tried in Texas is retainage. In Texas, the retainage was five percent; however, during the last legislative session, the state legislature reduced the retainage to four percent if recycled materials were used on the project. On a large contract, this one-percent difference is significant; on a million dollar job, it amounts to $10,000. This incentive does not increase the project cost at all. It simply changes the rate at which the contractor gets his money. The reduced retainage just became effective in Texas in September 1999, but it seems to have made some contractors more eager to use recycled materials.

Step 7 — Communicate

Communication and marketing is critical to the success of any effort to increase the use of recycled materials. Without it, the use of recycled roadway materials will not happen. Communication can happen via conferences, information showcases, videos, research summaries, information packets, the Internet, case studies, media coverage, periodical publications, special publications, and so forth.

The message bears repeating many times in many different ways through many communication "channels." One marketing guru stated that consumers need to be exposed to a message 27 times before it has the desired effect.3 Many people in governmental agencies are not comfortable with the stereotype they associate with the word "marketing." Perhaps it would help to think of this step as effective communication.

To be successful, communication efforts cannot just focus on DOT employees. Contractors, materials suppliers, recycled materials generators, and local road construction staff must also be included as target audiences. Generators of recycled materials would love to learn that there is a market for their materials and that there will not be any regulatory problems in using their materials in road construction. Convincing local road construction people to use recycled materials will be easier if the use is approved by the state DOT.

Many local road construction agencies do not have the resources or expertise to do this research on their own. But local road construction projects are ideal places to use these materials. When cities and counties use recycled roadway materials, they reduce their materials costs and their waste disposal costs. They get double savings.

While the common goal is to have each audience embrace recycled products, the message may need to be presented in a variety of ways to "speak to" the variety of needs of the different audiences. For example, engineers want to avoid failures. Contractors do not want a failure either, and they seem to be very bottom-line oriented — even more so than DOT engineers.

Attendees at TxDOT's Road to Recycling Conference had an opportunity to visit with vendors to learn more about recycled materials.

One of the most challenging tasks in communicating with all these different audiences is to get them to talk to each other. For the most part, many of these different audiences will have nothing in common except the recycled materials. They do not know anything about the other’s businesses, but they need to learn some basics in order to understand the potential markets. A municipal recycling coordinator, for example, needs to understand that road construction offers a potential market for glass and other materials collected from city residents. This recycling coordinator also needs to understand that there are standards and specifications for this end market — just as there are with other end uses. Road construction personnel need to understand that these recycled materials can meet existing standards and can be substituted for traditional materials. They also need to understand the economic factors to fully tap the potential savings.

Another potential audience is the media. A story in the local paper or on the evening news about the DOT’s positive efforts to use recycled materials and improve the environment will go a long way to counterbalance the negative media coverage that DOTs often receive concerning highway-related problems.

The bottom line is this: Everyone involved needs to understand the tremendous potential of recycled materials to save natural and financial resources, while maintaining a high-quality transportation infrastructure.

The TxDOT Experience

In Texas, more than 18 research projects have been conducted on the use of recycled materials in road construction.

One research project included the monitoring and evaluation of nine pilot projects across the state. Information showcases were held at the pilot project locations to share this knowledge with people outside the project. For those who could not attend, video footage was shot and used to produce a video and CD-ROM. The results of this research have been communicated in two Road to Recycling conferences attended by approximately 200 people each.

In addition, articles have been written for industry publications and a Web site has been developed. The Web site attempts to provide information that would be helpful to any of the different groups involved in increasing the use of recycled materials in road construction activities. It provides research summaries, specifications, department contacts, and much more.

As part of another communication effort, TxDOT proclaimed 1999 to be the "Year of the Recycled Roadway Materials." This year-long campaign communicated information about the potential of recycled roadway materials to the Texas road construction industry. Twelve target recycled materials were featured in a calendar with a picture and some basic facts about the material being highlighted for that month. Each month, to flesh out the featured material, a packet was produced and sent out to DOT engineers, contractors, and local road agencies. These packets included a brief, but comprehensive, assessment of how the material could be used in road construction and maintenance applications. Each packet contained a research summary, case studies, recycled materials availability lists, and specifications all pulled together in one easy-to-digest format.

The packets were mailed monthly to tie in with the calendar and to encourage readership. Mailing the information in small monthly doses seems to have worked. A survey accompanying the April packet revealed that 86 percent of the respondents usually or always read the packets. Also, 75 percent of the survey respondents indicated that the monthly packets made them somewhat or absolutely more receptive to using recycled roadway materials. (Refer to

TxDOT is also in the process of developing customized training programs addressing the specific recycled materials available in eight different regions of the state.


  1. David R. Wilburn and Thomas G. Goonan. Aggregates From Natural and Recycled Sources: Economic Assessments for Construction Applications — A Materials Flow Study, U.S. Geological Survey, U.S. Department of the Interior, Washington, D.C., June 1, 1998, p. 3. (Available online at
  2. Ibid, p. 1.
  3. Scott S. Smith. "May I?" Entrepreneur, October 1999, p. 92.

Rebecca Davio is the manager of the Texas Department of Transportation’s Recycling and Recycled Products Program. She has directed the department’s Recycling Program since its inception in 1993. She currently serves as the TxDOT representative on the Texas Recycling Market Development Board, the external policy chair of the Recycling Coalition of Texas, and the chair of TxDOT’s Environmental Research Technical Assistance Panel. Davio joined TxDOT in 1991, working with the department’s Alternative Fuel Vehicle Program. She has a bachelor’s degree in merchandising and a master’s degree in public affairs, and she is currently pursuing a doctorate in recycling and solid waste management. All her academic work has occurred at the University of Texas at Austin.