How one public works department developed a spec using recycled aggregate that includes toilets
| June 07, 2012 |
Recycling has reached a new level for the transportation construction industry.
The Public Works Department of the city of Bellingham, Wash., pushed the limits of recycled materials use with a street project that included 400 old toilets incorporated into concrete. The Public Works Department developed a specification using recycled aggregate, which allows for the use of recycled brick, concrete, tile, toilets, and other similar types of construction waste.
“We did it because it was the right thing — and it was fun,” Anthony Freeman, P.E., project engineer for Bellingham, tells Equipment World, Better Roads and Aggregates Manager magazines. “We got to play mad scientist. I think it [this project] really speaks about local partnerships, though.”
Freeman said the city was actively looking at using recycled concrete on the sidewalks. “Now, we have a spec that allows the city to do that,” Freeman says. “We are not only using toilets, but looking into capturing a bigger waste stream. There is not a huge market for recycled concrete, but we are going to enhance market for it.”
The city’s recent work on a recycled concrete aggregate spec for flatwork (curb, gutter, sidewalk, and driveway) concrete served as the foundation for the creation of Poticrete, Freeman says. The new spec — and Poticrete — meet a goal to reduce the use of virgin materials and to improve the regional market for crushed concrete, he says.
When Freeman received a call in February 2011 from Sustainable Connections, a local non-profit with both waste-reduction and green-building initiatives, he was asked if he could find a place in a city project for 400 high-flow toilets from a federally funded housing retrofit project. The city worked with the retrofit contractor and Cowden Gravel and Ready Mix to collect and crush the porcelain, then mix the aggregate in a few different batches for testing, Freeman says.
Eventually Cowden determined the best mix included about 20 percent porcelain by volume, and the city set about incorporating 40 cubic yards of Poticrete into a street project, Freeman says. The final product met all requirements for sidewalks, driveways, and curb/gutter installations.
Although this type of project does decrease the need for virgin aggregate, it’s not going to economically hurt aggregates operations, Freeman says. “We’ll always need our local aggregate suppliers for high-strength virgin aggregate,” he says. “But for applications that don’t take extensive structural loads, why not use recycled concrete? It’s also a developing market that our aggregate and concrete suppliers can be part of.”
The Meador/Kansas/Ellis trail project includes an asphalt overlay, new sidewalks, new curb and gutter, landscaping, storm water management, and several regional sidewalk and trail connections. A key intersection of two trails and three sidewalks provided a showcase location. The city installed 2,100 square feet of Poticrete along with a decorative band and educational plaque that provides public information on the city’s efforts to work with local businesses both to provide economic opportunity and to build more environmentally responsible public projects, Freeman says.
Currently, Whatcom County’s two regional solid waste management companies accept toilets for a small fee and provide them for future Poticrete installations. This use, along with other options for recycled aggregate, will help the city include more than 400 tons of recycled materials in concrete alone in street projects each year, Freeman points out.
“This is a situation where everyone wins,” he says. “This project and this use of toilets is an example of the strategic risks that public agencies need to take in this day and age to encourage local markets that support recycled materials and more sustainable road projects.”
This project received the first GreenRoads certification, according to Freeman.
Be sure to check out Equipment World’s (EW) sister publications, Better Roads and Aggregates Manager, either in print on the Web or in their digital editions (It’s very cool, just like EW’s digital edition — it flips just like a magazine), in the July 2012 issue.
(The photos for this blog post were courtesy of Anthony Freeman, P.E., with the Public Works Department for the City of Bellingham, Wash.)