Construction and demolition (C&D) materials are generated when new building and civil-engineering structures are built and when existing buildings and civil-engineering structures are renovated or demolished (including deconstruction activities). Civil-engineering structures include public works projects, such as streets and highways, bridges, utility plants, piers, and dams.
C&D materials often contain bulky, heavy materials such as Concrete, Wood (from buildings), Asphalt (from roads and roofing shingles),
Gypsum (the main component of drywall), Metals, Bricks, Glass, Plastics, Salvaged building components (doors, windows, and plumbing fixtures), Trees, stumps, earth, and rock from clearing sites.
C&D materials constitute a significant waste stream in the United States. These various C&D materials can be diverted from disposal and managed into new productive uses. EPA’s waste characterization report, the Advancing Sustainable Materials Management: 2018 Fact Sheet, estimates the C&D material generation and the mass quantities of the generated materials that were directed to next use or sent to landfills in the United States.
The 2018 Fact Sheet shows:
- 600 million tons of C&D debris were generated in the United States in 2018, which is more than twice the amount of generated municipal solid waste.
- Demolition represents more than 90 percent of total C&D debris generation, while construction represents less than 10 percent.
- Just over 455 million tons of C&D debris were directed to next use and just under 145 million tons were sent to landfills.
- Aggregate was the main next use for the materials in the C&D debris.
C&D waste generated during construction, demolition and Repairs
- According to the Technology Information, Forecasting and Assessment Council’s, or TIFAC’s, thumb rule if a new construction generates 40-60 kg of C&D waste per sq m, then taking an average of 50 kg per sq m, India has already generated 50 million tonnes (MT) of C&D waste in 2013. Over the last eight years, India would have produced 287 MT of this waste.
- As per TIFAC demolition produces 300-500 kg of waste which is 10 times of that generated during construction. If it is assumed that five per cent of the existing building stock gets demolished and rebuilt completely annually, then about 288 MT more of C&D waste would have been generated in 2013 alone because of demolition.
- TIFAC also says building repair produces 40-50 kg per sq m of waste. Assuming that one-third of the existing building stock underwent some sort of repair or renovation in 2013, India must have generated an average of 193 MT of C&D waste just from repair and renovation in that year.
Reducing the effects of construction and demolition (C&D) waste
Building materials account for almost half the solid waste generated worldwide. In Australia alone, about 40% of waste generated from construction and demolition is disposed into landfills. For this reason, Governments worldwide are turning to specific regulations and legislation to encourage the recycling of these materials into new revenue streams and new business opportunities.
What are some of the methods used by government agencies to manage C&D waste more effectively?
1. Waste Levies: Significant levies are often imposed upon C&D waste to encourage construction companies to look for alternative uses for the waste rather than sending it to landfills.
2. Waste Minimisation Funds: Funding collected via these levies is often used to set up waste minimisation funds which are then used to fund research and development projects in the recycling sector.
3. Waste Data: Another popular method is employing regulations that make the collection and reporting of waste data and information mandatory. This enables regulators to be more informed of the types of waste going to landfill so they can then look at ways to target specific waste streams in efforts to reduce their environmental impact.
4. Waste Mass Balance Reporting: This is another useful tool for regulators to gain greater visibility on the movements of waste materials through the waste facilities within their region. Waste Mass Balance Reporting requires all participants, typically licenced waste facilities and operators, to provide detailed quality data on the waste materials they receive and what is then done with them. This can be an essential tool in stockpile prevention and understanding what waste types are prone for illegal dumping.
NSW Environment Protection Authority (EPA) is a good example of a Government agency who is focused on reducing the effects of construction and demolition (C&D) waste. They recently announced a series of proposed reforms aimed at improving how C&D waste operators handle these types of waste. In addition, it is intended that they will address major concerns from within Government, industry and from the public around the transport of C&D waste from NSW to Queensland where it is cheaper to dispose of rather than recover and reuse in NSW.
Reducing the amount of C&D materials disposed of in landfills or incinerators can:
- Lead to fewer disposal facilities, potentially reducing the associated environmental issues, such as methane gas emissions, which contribute to global climate change.
- Offset the environmental impact associated with the extraction and consumption of virgin resources and production of new materials.
- Create employment and economic activities in recycling industries and provide increased business opportunities within the local community, especially when deconstruction and selective demolition methods are used.
- Reduce overall building project expenses through avoided purchase/disposal costs, and the donation of recovered materials to qualified 501(c)(3) charities, which provides a tax benefit. Onsite reuse also reduces transportation costs.
- Conserve landfill space.
Builders, construction teams, and design practitioners can divert C&D materials from disposal by practicing source reduction, salvaging, recycling and reusing existing materials, as well as by buying used and recycled products.
Source reduction reduces life-cycle material use, energy use and waste generation. UN’s EPA gives it the highest priority for addressing solid waste issues. While reuse and recycling are important methods to sustainably manage waste once waste has already been generated, source reduction prevents waste from being generated in the first place.
Examples of C&D source reduction measures include preserving existing buildings rather than constructing new ones; optimizing the size of new buildings; designing new buildings for adaptability to prolong their useful lives; using construction methods that allow disassembly and facilitate reuse of materials; employing alternative framing techniques; reducing interior finishes; and more.
In addition to changing the design of buildings, building systems and materials, C&D source reduction efforts incorporate purchasing agreements that prevent excess materials and packaging from arriving to the construction site.
Salvaging and Reusing C&D Materials
Demolishing existing buildings and disposing of the debris is not a sustainable practice. Recovering used, but still-valuable C&D materials for further use is an effective way to protect natural resources and save money. Deconstruction is the process of carefully dismantling buildings to salvage components for reuse and recycling. Deconstruction can be applied on a number of levels to salvage usable materials and significantly cut waste.
The major benefit of reusing materials is the resource and energy use that one saves avoided by reducing the production of new materials. Some commonly reused C&D materials and applications include:
- Easy-to-remove items like doors, hardware, appliances, and fixtures. These can be salvaged for donation or use during the rebuild or on other jobs.
- Wood cutoffs can be used for cripples, lintels, and blocking to eliminate the need to cut full length lumber. Scrap wood can be chipped on site and used as mulch or groundcover.
- De-papered and crushed gypsum can be used, in moderate quantities, as a soil amendment.
- Brick, concrete and masonry can be recycled on site as fill, subbase material or driveway bedding.
- Excess insulation from exterior walls can be used in interior walls as noise deadening material.
- Paint can be remixed and used in garage or storage areas, or as primer coat on other jobs.
- Packaging materials can be returned to suppliers for reuse.
Recycling C&D Materials
Many building components can be recycled where markets exist. Asphalt, concrete, and rubble are often recycled into aggregate or new asphalt and concrete products. Wood can be recycled into engineered-wood products like furniture and plastic-composite decks, as well as mulch, compost, and other products. Metals—including steel, copper, and brass—are also valuable commodities to recycle. Additionally, although cardboard packaging from home-building sites is not classified as a C&D material, it does make its way into the mixed C&D stream, and many markets exist for recycling this material.
Sometimes, materials sent for recycling end up being poorly managed or mismanaged. Asking your recycler a few questions, such as whether they are in compliance with state and local regulations, state licensing or registration, and/or third-party certification, can ensure the proper and intended management for your materials.
LafargeHolcim, U.S. Army Corps of Engineers announce agreement to recycle C&D material
LafargeHolcim, Switzerland, along with its subsidiary company, Geocycle, announced a cooperative agreement research project with the U.S. Army Corps of Engineers’ Engineer Research and Development Center (ERDC) in July 2021 to study how construction and demolition (C&D) materials can be used for energy recovery and mineral recycling.
Under this agreement, the ERDC will provide technical assistance and $3.4 million to conduct a waste characterization study and develop a basic research program to demonstrate how C&D debris from across U.S. military installations may be used to create alternative fuels and alternative raw materials for the production of new, more sustainable, construction materials.
“In 2018, the U.S. Environmental Protection Agency (EPA) estimated that approximately 600 million tons of construction and demolition debris was generated in the United States, which is more than twice the amount of generated municipal solid waste,” Sophie Wu, director of Geocycle North America, says. “The partnership with the U.S. Army Corps of Engineers will help us better understand this material and see how we can create a circular economy program leading to a zero-waste future.”
This research will utilize resources at Geocycle’s Holly Hill Research Center in South Carolina and Holcim Ltd.’s Global Innovation Center in Lyon, France. Geocycle, a provider of industrial, agricultural and municipal waste management services with U.S. headquarters in Dundee, Michigan, works to develop innovative waste management techniques combined with proven co-processing technology, the company says.
“We expect this partnership to lead to waste reduction opportunities at Army installations,” Stephen Cosper, an environmental engineer and project manager at ERDC, says. “We’re very excited about how this project can positively impact our military installations and our environment in the future.”
The research team will begin by conducting a waste characterization study at a number of military installations facing significant construction and demolition debris. Construction materials will then be evaluated for possible co-processing opportunities, including energy recovery, mineral reuse and mineral recovery. Information obtained as part of this research will help the USACE identify ways to reduce waste, increase its circular economy, and avoid landfill costs and associated emissions.
“In the U.S., LafargeHolcim’s sustainability goals are at the heart of our research agenda. While we are proud to offer some of the leading low-carbon, sustainable building products in the market today, we want to make sure we develop the next generation of materials needed to reach our net-zero goal,” Toufic Tabbara, CEO of U.S. Cement at LafargeHolcim, says. “This partnership with the U.S. Army Corps of Engineers will help us identify solutions that can help drive the circular economy, reduce landfill waste, and lower our carbon emissions nationwide.” The cooperative agreement is supported by funds appropriated to the Department of Defense, as well as the Army Corps of Engineers’ research organization, the Engineer Research and Development Center.