February 13, 2023
By Bart Fischer, Sr Public Administrator with Joe Carlson, Project Engineer and Amy Fredregill, Sr Director of Sustainability, WSB
Government entities, at all levels, are working on plans to reduce greenhouse gasses. Many cities have been establishing sustainability and climate plans that aim to decrease their carbon footprints while some states have enacted laws to support more climate-friendly building practices.
When it comes to building resiliency and establishing more sustainable practices, pavement isn’t always top of mind. Bart Fischer, Sr. Public Administrator, sits down with Joe Carlson, Materials Project Engineer and Amy Fredregill, Sr. Director of Sustainability to discuss the advancements in sustainable pavement and how cities can help achieve their resiliency goals
BF: First, what is driving the push for more sustainable pavement options?
AF: There is an increased focus across the nation to reduce greenhouse gases and build resiliency. A lot of this is being driven by evolving customer demand and federal, state and local government. I think we’ll start to see more incentives and expanded programs in the coming years related to this developing area of emphasis. For example, the Governor of New Jersey signed the Low-Carbon Concrete Law earlier this year. The bill allows producers to receive an income tax credit of up to 8% of the concrete cost for providing low-embodied carbon products on state projects. It’s thought to be the first tax-incentive-based legislation of its kind in the nation.
JC: We are also seeing this expansion across Minnesota. Recently the Minnesota Department of Transportation (MnDOT) issued a provision to their specifications that allows an increase in the Recycled Asphalt Pavement (RAP) content that new asphalt mixtures can contain. Prior to this adoption, most mixes were only allowed to contain up to 20% RAP. Increasing the allowable RAP content leads to a significant reduction of carbon dioxide (CO2) emissions while simultaneously bringing down the cost of asphalt for owners.
BF: Interesting. I didn’t realize that sustainable pavement options existed until recently. What are you seeing or hearing in the pavement industry?
JC: I’ve been hearing a lot of talk about concrete that has CO2 injected into the mix. This allows CO2 to be incorporated and locked into the concrete mixture and prevents it from being discharged into our atmosphere. Injecting the CO2 into the concrete has benefits including an increase in strength. The cost has little impact on the overall price of the concrete mix.
BF: Stronger concrete and competitive pricing seems like a win for everyone. Anything similar in the market for asphalt?
JC: There is a recycled fiber reinforced asphalt available that is used for mill and overlays that provides performance benefits that dovetail with advancing sustainability goals. The fiber reinforced asphalt contains recycled plastic fibers that prevent what we refer to as reflective cracking. Reflective cracking occurs when there are cracks left in underlying layers of asphalt after milling. These underlying cracks come through (reflect) into the new pavement overlay surface rather quickly. The recycled plastic fibers are said to extend the life of the asphalt and significantly reduce the number of reflective cracks that develop. Extending the lifecycle advances sustainability because it reduces cost, waste, materials use and the overall footprint of a project.
How can cities implement sustainable pavement in their communities?
AF: Sustainable pavement is one area where cities can build resiliency and help reduce their carbon footprint, sometimes as stand-alone efforts, or increasingly as part of climate or sustainability plans adopted by cities we work with across the state. Net-zero goals and climate plans feel overwhelming but starting small has a major impact by testing out new approaches, engaging key stakeholders to get their feedback and build on their expertise, and learn from the experience. Sustainable pavement is one example of a minor change that has lasting impact.
JC: We don’t need to rely on construction materials to make an impact. Our industry tends to overbuild and overengineer leading to more expensive projects, resulting in a larger carbon footprint. Communities can achieve success by ensuring a strong geotechnical exploration program is performed prior to any type of roadway construction or reconstruction. The results of these explorations provide the community with vital information and options for pavement construction or rehabilitation methods. In addition, a robust pavement management plan results in a more strategic approach to maintaining and repairing roads before pavement rehabilitation options become limited and expensive.
Bart Fischer has over two decades of experience in public administration. Throughout his tenure, he’s worked in five Minnesota communities as the city or assistant city administrator. Bart joined our firm in 2019 as a senior public administrator and focuses on lending his public service expertise to our clients.
[email protected] | 651.485.1839
