Materials
What happens to scrap steel and clean concrete after a demolition?
- recycling
- scrap steel
- concrete
Published
Scrap steel is separated on site and sent to a scrap metal recycler, where it's sorted, processed and melted into new steel. Clean concrete, kept free of wood, soil and garbage, goes to a crushing facility and is processed into aggregate that can be reused as base material.
Both only work if the material is kept separate from mixed debris during the demolition. Here's how that happens and what it depends on.
Separating on the ground
Separation starts as the building comes down. The excavator operator pulls metal out of the pile and sets it aside, and concrete and masonry are stacked away from wood and mixed waste. On a house, the metal might be ductwork, roofing, siding and appliances. On a commercial or industrial building, it's structural steel, decking, cladding and racking.
It's easier to separate as you go than to sort a mixed pile afterward, so the order of work is often set with separation in mind.
Where the steel goes
Metal is loaded into a trailer or bin and taken to a scrap recycler. There it's:
- Weighed and graded by type
- Cut or sheared to size
- Sent on to mills where it's melted and made into new steel
Where clean concrete goes
Clean concrete and masonry go to a facility that crushes them into aggregate. Rebar is pulled out by magnet during crushing. The aggregate can be reused as road base, fill or backfill, depending on the grade.
"Clean" is the key word. Wood, plastic, drywall and soil mixed into the load can mean the facility won't accept it, and it goes to landfill instead.
What stops material being recycled
Some materials can't go to a normal recycler. Asbestos-containing materials must be removed under O. Reg. 278/05 and disposed of as asbestos waste, which is why the designated substance survey required under section 30 of the Occupational Health and Safety Act comes before demolition. Painted concrete or brick with lead paint may need testing. And some facilities don't accept concrete mixed with brick or block.
What it depends on
How much gets recycled depends on the building, the space on site to keep piles apart, and what the nearby facilities accept at the time. A tight lot in Woodbridge might limit separation; an industrial lot in Concord usually has room for several piles.
Other materials that can be recovered
Steel and concrete are the big ones, but they aren't the only materials that can leave a demolition site for reuse rather than landfill. Depending on the building and what local facilities accept at the time, recovery can also include:
- Clean wood and dimensional lumber, which some facilities chip for fuel or mulch
- Copper wiring and piping, graded separately from steel
- Aluminum windows, siding and flashing
- Brick and block, where a facility takes masonry
- Asphalt from driveways and parking areas, which is recycled on its own
Keeping records
Some owners and builders want to know where material went, especially on commercial projects with sustainability targets. Scrap and recycling facilities issue weigh tickets for each load. If you need them, ask for them in the scope before work starts so they're collected as the loads go out.
A note on hauling
Concrete and steel are both heavy, so trailers and bins reach their weight limits well before they look full. Loads are sized to stay legal on the road, which is part of why separate loads are planned from the start.
What we do about it
On every structural demolition and concrete removal job, we separate metal and clean concrete from mixed debris on the ground. We'll tell you at the site visit how much room we'll need for separate piles on your lot. Request a free estimate to start.
Frequently asked questions
- Is all demolition steel recycled?
- Most metal from a demolition can go to a scrap recycler, as long as it isn't contaminated with materials the recycler won't accept.
- What makes concrete clean?
- Concrete and masonry without wood, drywall, plastic, soil or garbage mixed in.
- Does rebar stop concrete being recycled?
- No. Rebar is usually removed by magnet during crushing.
- Can crushed concrete be used back on my site?
- Sometimes, as base or fill, depending on the grade and your engineer's or builder's requirements.