Construction material recycling is critical to reducing the total quantity of the waste stream. In areas where construction or renovation is brisk, the impact on local landfills and other solid waste facilities is major.
Percentages of total solid waste in the landfill vary from 15% on the low side to 30% or higher in communities that are growing or rehabbing rapidly. In addition to these impressive quantities that can be kept out of the landfill, another advantage of reducing building material waste is that there are relatively few individuals to convince of the merits of this practice.
Like all recycling, an even better alternative is direct salvage and reuse. This topic is discussed near the end of this page.
Leftover drywall, lumber, and metal studs and other items can be recycled, although not every city will have a convenient recycling plant able to handle these materials. If demolition occurs prior to new construction, the options are even greater. Likewise concrete foundations and walls from the demolition process can be recycled.
Recycling of any leftover construction material or waste from a demolition process reduces the quantity of new materials needed, saving both the costs of mining or manufacturing of the construction materials and the energy involved in transporting those items.
Asphalt shingles are estimated to account for about a third of
construction wastes reaching landfills. Both the torn-off and worn-out
shingles, and the leftover new shingles from re-roofing jobs can be
ground and then analyzed for incorporation into a hot asphalt mixture
used for most paving jobs of any size.
This is a particularly important example, since asphalt shingles might contain as much as 35% asphalt cement in them, a key ingredient required for new asphalt paving. Asphalt from demolished driveways can be recycled also. Even if the existing driveway will be refurbished, almost any asphalt plant with the will to do so can incorporate the "millings," which means the part of the asphalt pavement shaved off the top prior to re-paving, into the hot mix for new asphalt.
Recycled concrete is acceptable as a source of aggregate, an important ingredient in making new concrete. Recently standards for incorporating recycled concrete have been set by the American Society for Testing and Materials (ASTM) and American Association of State Highway and Transportation Officials (AASHTO).
Sources for concrete that could be recycled include former concrete roads, curb and gutter systems, airport runways, or building foundations. There seems to be less experience with recycling concrete than asphalt, so significant learning on the part of the industry still is needed. Crushed concrete also can be used as aggregate alone, what most of us would call gravel at our homes.
Recycled drywall is used in the manufacture of new drywall.
Alternatively, it can be an ingredient in cement or fertilizer. There’s
a fairly low rate of drywall scrap recycling, but if you've ever done a
major home remodeling project, you probably can testify to the fact
that there are actually a number of leftover odd pieces. To date most
of these are headed for the landfill, and the contractor must pay for
All of the above depend on education and persuasion of construction contractors and "do-it-yourselfers" of the importance of recycling to society, or to their pocketbooks if the contractor can do their own recycling. Homeowners also can be helpful through taking advantage of local opportunities to recycle building materials.
In many communities Habitat for Humanity offers ReStore, a place where building supply stores, contractors, demolition companies, and individuals donate surplus construction materials, which Habitat in turns resells in a retail format at a fraction of the cost of new supplies.
Other local versions of construction material recycling may be in operation in your area. In Portland, latex paint recycling leads to blending of paints for re-sale. Metal recycling is plentiful in any large community.
Like many less familiar materials recycling ventures, lack of information about how and where interested parties can recycle, as well as the small inconveniences involved, contributes to a low rate of recycling.
For more information, the Construction Materials Recycling Association offers specialized sites for concrete, drywall, and shingles. New recycling enterprises are emerging at a fast pace, so it is worth checking them out.
We don't want to leave the impression that the only value of construction material recycling is reduction of volume in the landfill. We should emphasize that the very best policy would be to reduce energy use, greenhouse gas emissions, and our carbon footprint in general through not manufacturing or transporting unnecessary items, refusing to demolish what can be renovated or adaptively reused, and then recycling what cannot possibly be reused.
So even though we're on a page that advocates for construction material recycling, preventing waste generation is perhaps an even more important strategy. Surely waste reduction isn't such a radical concept.