By Tom Peterson, Contributing Author
Asphalt pavements have a long history of sustainable success. For many years, the asphalt industry has supported sustainability goals and has partnered with agencies to implement a variety of materials, design practices, construction standards and maintenance applications that are considered sustainable.
These practices are now becoming part of everyday project delivery.
A number of states, including Colorado, have implemented benchmark reporting programs that include Environmental Product Declarations (EPDs) to track, monitor and evaluate the environmental impact of construction materials including asphalt, asphalt materials, cement, concrete, and steel.
The Colorado Asphalt Pavement Association (CAPA) and the other construction materials associations are partnering with the Colorado Department of Transportation (CDOT) to implement the new program and comply with the enabling legislation.
The learning curve has been steep for all involved.
Asphalt producers now have a couple of construction seasons under their belt in submitting the EPDs and understanding the impact that different assumptions and material components have in the results.
Variables that impact the EPD results incude the amount of asphalt binder, modified versus unmodified binder, different aggregate types and the percent of sizes of recycled asphalt pavement, lime or no lime and haul distance.
In response to the EPD requirement, CAPA has established an Environmental and Sustainability Committee with the mission of advancing sustainable practices within the asphalt industry. The goal is to promote innovative solutions, reduce environmental impact and foster responsible stewardship to benefit Colorado’s communities and industry.
The committee guides the use of best practices to move the industry forward. The committee’s co-chairs are Mike Skinner, CAPA’s director of engineering, Erin Kunkel, environmental manager, and Martin Marietta. They have been instrumental in providing guidance on asphalt industry environmental initiatives.
“Being proactive allows the industry to be well represented and help ensure that proposed environmental regulations and requirements are as practical as possible, and give the industry the best opportunity to comply,” said Kunkel.
Green Asphalt
Asphalt is the most recycled material in the United States. The asphalt industry is proud of its efforts to be good neighbors, reduce its carbon footprint and become a leader in sustainability in the construction industry.
To that point, the asphalt industry of Colorado recognizes three elements within our business that are low hanging fruit to further increase an already environmentally friendly process and reduce the EPDs.
Streamline Warm Mix Asphalt: Innovative technologies known as Warm Mix Asphalt / Workability Mix Additive (WMA) are making asphalt an even more sustainable material. Warm-mix technologies employ a variety of methods and materials; what they have in common is the ability to reduce the temperatures at which pavement material is produced and placed on the road.
Expand Recycled Asphalt: The asphalt industry reuses and recycles nearly 100 million tons of its own product every year, making it America’s number one recycler. It saves hundreds of acres of landfill space each year. Most statewide agencies currently allow for the inclusion of RAP (approximately 20% - 25%). A positive adjustment would be to incrementally increase the usage of RAP and implement new Balanced Mix Design Approach.
Allow Alternative Anti-Striping Agents: Colorado is one of the last few states that does not allow for the use of liquid anti-strip. There is a potential of significant reduction in carbon dioxide (Co2) by allowing the use of liquid anti-strips. A positive adjustment would be to evaluate the use of liquid anti-strips.
Green Streets Colorado
The pressure on public works officials to implement sustainable practices in project delivery is growing. It is not uncommon for elected officials to suggest the use of materials or practices that are well intended but may adversely impact quality, performance, cost or that do not take into consideration the sustainable practices already being used.
To address this, we have launched a Green Streets Colorado Initiative that will provide recognition to those entities that have adopted specifications and standards that support sustainability in materials use, pavement design and construction.
The asphalt industry is responding proactively to EPD requirements and enhancing the sustainability of asphalt pavements.The industry has a great story to tell regarding what is already being done and are aware of numerous possibilities to make asphalt pavements even more sustainable.
The future is bright for the industry, and we look forward to supporting asphalt users at all levels with sustainability initiatives. RB
Thomas Peterson, P.E., is the executive director of Colorado Asphalt Pavement Association (CAPA), which is a 277-member organization and the voice of the 9-million-ton asphalt industry of Colorado. He can be reached at [email protected].
CDOT: EPD Implementation – Q/A
Craig Wieden, P.E., State Materials Engineer/Materials & Geotechnical Services Manager, [email protected]
Hailey Goodale, Sustainable Materials Engineer, [email protected]
What led to the EPD requirements in Colorado and what are the goals?
CDOT's Environmental Product Declaration (EPD) program was developed and implemented to comply with House Bill 21-1303, also known as the "Buy Clean Colorado" Act, which was passed in July 2021. The legislation directed both the Colorado Office of the State Architect (OSA) and the Colorado Department of Transportation (CDOT) to work towards the reduction of greenhouse gas emissions. While both agencies are working under the same overarching goal, they have distinct compliance requirements, including variations in timing, material categories, product quantity limits, and Global Warming Potential (GWP) thresholds. Specifically, CDOT's portion of the bill mandated that the agency collect EPDs for eligible materials, such as cement and concrete mixtures, asphalt and asphalt mixtures, and steel, on projects advertised on or after July 1, 2022. This data was used to establish maximum GWP limits for eligible materials, which were published as policy on January 1, 2025. These limits will go into effect for projects advertised on or after July 1, 2025. Further information on CDOT’s Buy Clean Requirements can be found in the CDOT Field Materials Manual, Appendix O, and on the CDOT EPD webpage. Additionally, the OSA's implementation requirements for the bill are available on their website.
What impacts do you see on the industry and how will the information be used?
While EPD requirements are relatively new to the asphalt industry in Colorado, as a whole, the asphalt industry in the US has been well positioned to succeed with EPD requirements, as the National Asphalt Pavement Association (NAPA) has already established a clear process for developing EPDs. NAPA serves as the Program Operator for the Product Category Rules (PCRs) for Asphalt Mixtures, and it has created a tool that allows asphalt mixture producers to generate EPDs in a consistent manner. The tool aids in collecting and reporting various data, such as plant energy usage, water usage, material haul distances, and the constituents of the asphalt mixtures. CDOT was also mindful of impacts to the industry and has worked to minimize the burden on contractors and suppliers by developing small quantity thresholds and minimum project material cost thresholds. Under these thresholds, the EPD requirements will not apply. For situations where EPDs are unavailable, CDOT will handle requests for waivers on a case-by-case basis. As suppliers become more familiar with the EPD development process, they may identify opportunities for improving their practices, such as using more sustainable burner fuels, increasing the use of recycled materials, reducing haul distances, and optimizing transport methods.
It's important to note that EPDs should only be used for comparisons between materials that meet the same specifications and performance criteria, and they should not be used to compare asphalt with concrete. Additionally, the collection and use of EPDs should never be a justification for not meeting performance or service life requirements. CDOT utilized the EPDs developed for CDOT projects/mixtures to benchmark our current asphalt mixture Global Warming Potential and subsequent Global Warming Potential limits. EPDs will continue to be used to evaluate asphalt mixtures used on CDOT projects related to conformance to the GWP Limits that have been established.
What do you see coming from the Low Carbon Material Grants?
CDOT plans to use the Federal Highway Administration's (FHWA) Low Carbon Transportation Materials (LCTM) grant funding to support the growth and enhancement of its EPD program. Several activities are planned under this initiative, though this list is not exhaustive. One of the primary goals is to ensure that CDOT's EPD program aligns with the Environmental Protection Agency's Interim Determination of Low Carbon Materials. To make the process more efficient, CDOT aims to improve the collection and submission procedures, as well as enhance data analysis capabilities. Additionally, CDOT plans to integrate EPDs into current materials sampling and testing forms and processes. Another focus will be developing methods for selecting and qualifying "low carbon materials" and continuing to update and maintain the GWP limits. One of the LCTM program requirements is to collect Energy Star Performance Scores from manufacturers when available, so CDOT will develop and implement a program to do so. CDOT will also assess the engineering performance of materials, evaluate current specifications, and develop new project-specific provisions for projects where low-carbon materials are to be used. Other activities include laboratory testing and material performance evaluations using instrumented test sections, as well as placing eligible low-carbon transportation materials on applicable construction projects. These initiatives are aimed at advancing the use of low-carbon materials in transportation infrastructure and ensuring that the materials used meet both environmental and performance standards.
