When I approached my neighbor’s construction site, Edward Small of Sheridan Brick & Stone Work was chiseling off construction waste— mortar from old bricks to be exact. He suspects they were salvaged from a nearby Maine paper mill, and his eyes lit up when he spoke of putting them to use in a wood-burning Russian masonry stove. There is a small revival of brick craftmanship in Maine, literally with the same materials as buildings are being deconstructed and repurposed.
Breaking down construction waste
In addition to the wonderful aesthetic possibilities, this practice is a sustainable alternative to disposing of demolition waste in landfills. In 2013, 530 million tons of construction waste (and demolition waste too) was generated in the United States, according to the U.S. Environmental Protection Agency. The materials are a hodgepodge of lumber, drywall, metals, brick, concrete, carpet, plastic, tile, and other materials. Portland cement comprises over half of all demolition waste, with wood products coming in a distant second. In fact, cementatious concrete is the second most widely used material in the world, second to water.
Encouraging construction and demolition waste recycling
Rising landfill costs help make the recycling of demolition waste more economically feasible in addition to being more sustainable. Construction projects that are seeking Leadership in Energy and Environmental Design (LEED) certification can also earn points for recycling construction and demolition waste, helping to create a market for waste management facilities that are offering such services. This often involves sorting wood, metal, cement, gypsum and other waste on-site into containers. This approach is most advantageous when there is enough space and large quantities of just a few waste materials. Waste management companies then look for local needs for such materials. Ideally, the recycling of this waste prevents the extraction of virgin materials and can help reduce transportation emissions when there are opportunities to use the materials locally.
Some demolition waste recycling facilities can process and recycle loads of mixed materials, eliminating the need to sort materials on the construction site. This is especially helpful when space is limited and it isn’t possible to have multiple dumpsters for different types of materials. As demolition waste recycling advances, the cost of processing this waste may also come down, making it more profitable. Like some other types of recycling, the sorting of demolition waste can be labor intensive. This in turn drives up recycling costs, but also creates green jobs.
Advancing construction waste recycling
Regulations have also helped push the construction and waste management industries to seek greener uses of construction waste. In the European Union (EU), the Waste Framework Directive requires EU member states to recover a least 70% of construction and demolition waste by 2020. This is urging the industry to mature, both cutting costs and boosting efficiency and environmental performance. Recycling technologies are advancing that allow materials to be more readily sorted and cleaned, creating more recycling possibilities. This helps make demolitions waste more profitable, encouraging future growth. As the volume of recycled demolitions waste increases, new uses and markets will open up for these materials.
“I think we need to look beyond the quantity and focus on the quality of the recycled materials that we produce,” said Peter Craven, head of marketing at CDE Global. “Many of the countries in the EU are well on course to comfortably meet the targets of the Waste Directive so we need to move on to the next level in terms of how we can extract maximum value from this waste stream and further enhance the quality of recycled products.”
Concrete and asphalt recycling
A majority of construction and demolition waste is Portland cement and some of this is recycled and used to make aggregate. This process typically involves grinding up concrete and sometimes asphalt for use in making roads as an aggregate base, aggregate subbase, or shoulders. It is also sometimes used for resurfacing gravel roads, as a base for building foundations, and as fill for utility trenches. Although these uses may not sound glamorous, they do help prevent the extraction of primary materials.
Wood product recycling
Demolitions and demolition waste commonly contains lumber, trim, and wood pallets that can be reused in a variety of ways. Recycled wood combined with adhesives can be used to make many kinds of engineered wood products. Common products include oriented strand board, particle board, and plywood. Aside from some of the adhesives containing volatile organic compounds such as formaldehyde, a toxic air pollutant – recycled wood products can be quite green because they make use of scraps or recycled lumber. It is also inspiring to see closed loop recycling, where one product is recycled to make a similar product, reducing the need for virgin materials.
Some recycled wood feedstock is also used to produce biofuels and electricity. Greenleaf Power with its headquarters in Sacramento, California is a good example. The company operates five biomass to electricity plants that use tree trimmings, agricultural waste, and clean construction and demolition debris to power homes and businesses.
Wood waste is also used as landscape mulch, soil conditioner, animal bedding, and as a compost additive. However, some wood products are treated with flame retardants, chromate copper arsenate, and other products to preserve the wood. These treatments can be harmful to people, pets, and wildlife and may not be desirable in landscaping products.
Like other types of recycling, wood waste must be separated from other types of waste, cleaned to remove contaminants and fasteners, and processed by grinding or chipping the wood. The final use of the recycled wood often depends on how clean the recycled wood feedstock is.
Reusing construction materials
Similar to other types of waste materials, reusing demolition and spare construction materials like Edward Small does is one of the greenest options as it reduces the energy and other resources needed in processing. Local networks exist that vary by location for sourcing such materials. Habitat for Humanity’s ReStore accepts used building materials that are in good condition. Doors, plumbing materials, spare tiles or carpeting, cabinets, and appliances are typically accepted. Because Habitat for Humanity is a 501c3 nonprofit organization, donations may be tax deductible. Shopping at the ReStore also provides some green construction options when completing construction and remodeling projects.
Feature image credit: Amy Johansson / Shutterstock