Apr 01, 2022Four Recycled Materials Civil Engineers Can Reuse

Civil Engineers Help the Environment with Recycled Construction Materials

You might not think of building things like roads and bridges as the most environmentally-friendly endeavors, but in fact, civil engineers reuse recycled materials more than most industries.

The structures we design and build are meant to last for many years. They need to be sturdy, safe, and cost-effective, and they need to withstand the elements and minimize their impact on the world around them. Recycled construction materials are part of what makes that possible.

Recycled Materials Reused in Civil Engineering

There are many different types of materials used in civil engineering work. Each type plays a unique and important role in the design and construction of highways, bridges, waterways, and other structures.

Some of the most commonly used (and reused) materials are also some of the most commonly recycled materials. Specifically, we use and/or produce:

• Recycled Asphalt Pavement (RAP)
• Fly Ash for Concrete and Recycled Concrete
• Bridge Steel, and
• Recycled Plastics

Recycled Materials: Asphalt

Recycled asphalt pavement, also known as RAP, can comprise up to 38 percent of the asphalt paving for a new road. The asphalt is milled, hauled, ground, and remixed in with virgin asphalt and other aggregate materials, and finally with liquid asphalt cement to bind it all together.

A 2020 article titled “Asphalt Industry Upholds Stellar Reputation as Top Recyclers“ published by the National Asphalt Pavement Association (NAPA) asserts, “According to the latest industry survey by NAPA in partnership with the Federal Highway Administration (FHWA), our industry reclaimed 97 million tons of RAP for future use, saving enough landfill space to fill up the dome of the U.S. Capitol 1,223 times.”

Recycled Materials: Concrete

One of the other most common recycled construction materials we use is cement. Recycled cement can be a component of highway pavement, piers, abutments, and substructures for bridges below the deck.

Like asphalt, concrete is often made from recycled materials, and it can also be recycled itself to form aggregate to go back into other asphalt and concrete mixes.

One of the recycled materials that often goes into cement is fly ash, which is a waste byproduct of major industrial processes like coal-burning electricity generation. Instead of letting it go into the air or a landfill, we’re able to repurpose it to make pavement.

Recycled Materials: Bridge Steel

Steel is a primary material in bridges. While it can take as long as a century to need replacement, when it’s time, there’s a lot of steel to scrap and reuse. Even small bridges can contain many millions of pounds of steel.

Because it can be recycled repeatedly without losing its structural strength, steel scrap is a widely available and valuable recycled material for many construction projects - even new bridges!

Additionally, the state of Ohio has started a pilot campaign to upcycle old state-owned steel stringers and give them to county agencies. The Ohio Department of Transportation has recently released a video on their most recent collaboration with the Muskingum County Engineer's Office. For more information, visit the Ohio Department of Transportation's website.

Recycled Materials: Plastics

You might not imagine plastics as a recycled construction material, but we can use it in a number of ways. Recycled plastics can actually go into some asphalts used in highway construction.

We also use recycled materials to replace the lumber on highway guardrail posts. You drive by them every 12 feet, and historically, they’ve been anchored by a 6x6 inch block made of timber. Now we can spare the trees by using a block of recycled plastic instead.

Talk to Us about Recycled Materials for Your Projects

If you want to hear more about recycled construction materials or if you have a project you think we could help you with, please contact us to get the conversation started.