Construction and Demolition Debris Recycling

Urban wood waste is the portion of the wood waste stream that can include:

• Sawn lumber
• Pruned branches
• Stumps
• Whole trees from street and park maintenance

Wood waste is, by far, the largest portion of the waste stream generated from construction and demolition activities.

Treated Wood Waste

Wood treated with chemicals for preservation against insects, microbes, etc., may need to be managed using alternative methods. CalRecycle has an LEA guidance on treated wood waste handling.

Processing

• The wood waste processors vary in what they require for a feedstock.
  • Some request only clean wood that is untreated or unpainted, while others will take a mixture of waste wood.
• Disposal fees vary with each facility, and some facilities may pick up loads and supply drop-off boxes. Contact the wood waste processors in the area to determine the most cost-effective option for each situation.

Videos

Wood and Organic Waste: YouTube (00:04:12)

Drywall is made of a sheet of gypsum covered on both sides with a paper facing and a paperboard backing. Gypsum is calcium sulfate dihydrate (CaSO4·2H2O), a naturally occurring mineral that is mined in dried ancient sea beds.
Drywall can be recycled into new products, resulting in:

• Creating business opportunities
• Saving money
• Helping local governments reduce disposal

Problems of Traditional Handling Methods

• Landfill: Hydrogen sulfide gas may be produced when landfilling gypsum, particularly in a wet climate.
  • Several conditions are required, including a moist, anaerobic environment and a low pH.
  • Hydrogen sulfide gas is toxic at high concentrations (~1,000 parts per million) and has a foul, rotten-egg odor.
• Incineration: Incineration may produce toxic sulfur dioxide gas. Drywall is not incinerated in California.

Drywall waste can be reduced by:

• Constructing standard-sized walls and flat ceilings.
• Ordering custom-sized sheets for nonstandard walls.
• Finding substitutes that are reusable, such as modular demountable partitions for commercial buildings.

Drywall waste can be reused in the following ways:

• Gunite Support: Gunite is a concrete sprayed on at high pressure. Pieces of new construction drywall can be used to support gunite as it is being sprayed.
• Construction Site Reuse: Drywall scraps can be placed in the interior wall cavities during new construction. This will eliminate the disposal and transportation costs.
• Donation: Habitat for Humanity is a nonprofit organization that builds affordable homes with donated materials. Several local chapters accept new drywall sheets of half size or larger.

Siting

Siting a drywall recycling plant may require certain state and local permits, such as air, water, zoning, and possibly solid waste.
Businesses starting or expanding into recycling activities may get financial, technical, marketing, business, and permitting assistance from their Zone Contacts.

Asphalt shingle scrap can be used in a variety of products, including:

• Asphalt pavement,
• Aggregate base and subbase,
• Cold patch for potholes, sidewalks, utility cuts, driveways, ramps, bridges, and parking lots,
• Pothole patch,
• Road and ground cover,
• New roofing, and
• Fuel oil

Asphalt roofing shingles are made of a felt mat saturated with asphalt, with small rock granules added, and are described as follows:

• Asphalt cement: 19 to 36 percent by weight. Asphalt used in shingles is considerably harder than asphalts used in pavement.
  • Organic shingles contain 30 to 36 percent asphalt.
  • Fiberglass shingles contain 19 to 22 percent asphalt.
• Mineral filler/stabilizer (limestone, silica, dolomite, etc.): 8 to 40 percent (90 percent is smaller than .15 mm, 70 percent is smaller than .08 mm.)
• Mineral granules (ceramic-coated natural rock, sand-sized): 20 to 38 percent.
• Felt backing (mat): 2 to 15 percent. There are two types of mats:
  • Organic felt, made with paper (cellulose).
  • Fiberglass felt.
  • Waste Stream Composition

Siting

Siting a shingles recycling plant may require certain State and local permits, such as air, water, zoning, and possibly solid waste. Businesses starting or expanding into recycling activities may get financial, technical, marketing, business, and permitting assistance from their Zone Contacts.

One of the primary uses of cold patch is filling potholes, so it is also called a pothole patch.
Cold patch can also be used to:

• Construct sidewalks
• Fill utility cuts
• Repair driveways
• Fix bridges
• Repair parking lots

Recycled-Shingle Cold Patch

Recycled-shingle (R-S) cold patch can be made with either manufacturing scrap or old tear-off roofing shingles. The patch could use virgin aggregate or reclaimed aggregate, which is obtained from crushing asphalt pavement.

The benefits of using recycled-shingle cold patch include:

• Improved pavement performance
• Possible economic savings
• Ease of use compared to traditional patches in the following ways:
  • Lighter weight with a lower weight-to-volume ratio.
  • No equipment is needed. Just fill the crack or pothole and tamp it down with a shovel or drive over it.
  • Time flexibility. It doesn’t harden as quickly as HMA, so there’s no hurry to use it. After applying, traffic can be allowed over the area immediately.
• Landfill space savings
  • The amount of asphalt roofing shingles landfilled in California is estimated at 1.2 million tons per year or about 3 percent of the waste stream.
• Resources Savings
  • All the asphalt needed in the patch can be supplied by the shingles.

California Specifications

One key to opening California markets for R-S cold patch is to have the product tested by the Caltrans maintenance department. Caltrans’ testing of new road products adds a high level of confidence to a product or method.
For information on Caltrans procedures, visit the Working with Division of Engineering Services.

Pavement is the surface layer of a roadway. Asphalt pavement is usually referred to as asphalt concrete, or AC. The benefits to recycling asphalt shingles in asphalt concrete include:

• Saving landfill space
• Possible economic savings
• Improved pavement performance
  • Asphalt used in shingles is harder than pavement asphalt, which provides:
    • Proved resistance to rutting
    • Increased stability
    • Decrease in temperature susceptibility
    • Improved compaction
    • Improved rideability index

California Specifications

The key to opening large California markets for asphalt shingles in asphalt pavement is to allow the shingles in California’s construction specifications. The specifications most widely used in California are Caltrans specifications and the Greenbook.

• The Paint Stewardship Program ensures that leftover paint is reused, recycled, or properly disposed.
• The Carpet Stewardship Program ensures postconsumer carpet is reused, recycled, or properly disposed.