Crushed Concrete: Uses, Grades, and Cost

Every year the US demolishes enough concrete to rebuild a mid-sized city, and most of it gets a second life under someone’s driveway. Crushed concrete — old slabs, foundations, and curbs run through a crusher and screened to size — sells for 20 to 40 percent less than virgin limestone or granite gravel while compacting into a base that is, for many jobs, functionally better. Contractors have quietly preferred it for decades. Here is how recycled concrete aggregate is graded, where each grade belongs, what it costs by the ton and yard, and the few places you should still pay for new stone.

What Crushed Concrete Is

Recycled concrete aggregate (RCA) starts as demolition debris trucked to a recycling yard, where crushers reduce it, magnets pull out rebar and mesh, and screens sort the product by size. The result looks like gray angular gravel flecked with the original stone. Because the crushed particles carry residual unhydrated cement, RCA does something virgin gravel cannot: after compaction and a few wettings, the fines partially re-cement, locking the layer into a semi-bound crust. That self-binding behavior is why a crushed concrete driveway stops shifting and rutting sooner than one built on plain washed stone.

Quality varies by source. A yard crushing clean highway slab sells a consistent product; mixed demolition debris can carry brick, asphalt chunks, or fragments of tile. Ask what feedstock the yard crushes, and eyeball a handful before ordering 20 tons.

The Grades That Matter

Recycled concrete is screened into the same size designations as quarry stone, with regional naming quirks:

• CA6 / road base / 21AA (crushed concrete version) — 3/4 inch down to dust, fines included. The workhorse grade: compacts to near-solid, self-binds, and forms the base under driveways, slabs, patios, and sheds. In some regions this is sold as “crusher run” or “dense grade” RCA.
• #57 crushed concrete — clean 3/4-1 inch stone with the fines screened out. Drains freely, will not compact into a crust, and does the jobs washed #57 gravel does: French drains, pipe bedding, drainage layers behind retaining walls, and top-dressing muddy lanes.
• #2 / 3-inch minus — large 2-4 inch chunks for stabilizing soft subgrades, building construction entrances, and choking mud before finer lifts go down.
• Screenings / fines — 1/4 inch minus, the sand-like byproduct. Levels paver bases in a pinch and fills trenches, though concrete-derived fines are alkaline; keep them away from planting beds.

Where Crushed Concrete Excels

Driveway bases are the flagship use. A typical residential build-up runs 4 inches of compacted CA6-grade RCA under 2 inches of a finer top course, compacted in 2-3 inch lifts with a plate compactor. Within a season, the surface knits into a firm crust that sheds rain and resists washboarding better than loose gravel — many rural owners simply run crushed concrete as the finished surface and re-dress it every few years.

Beyond driveways, RCA base performs under concrete slabs, paver patios, retaining wall footings (the clean #57 version behind the wall for drainage), gravel parking pads, walkways, and as backfill where free drainage matters more than looks. Highway departments across the country now spec RCA for road base, which tells you everything about its structural credibility — it routinely meets the same compaction and bearing standards as virgin dense-graded aggregate.

Cost: Crushed Concrete vs. Gravel

Prices swing by region and hauling distance, but the recycled discount is consistent:

• Crushed concrete (CA6-type base): $12-$25 per ton, or roughly $18-$38 per cubic yard
• Crushed concrete #57 (clean): $16-$30 per ton
• Virgin limestone road base: $20-$40 per ton
• Virgin washed #57 gravel: $28-$50 per ton
• Delivery: $75-$150 per load within 15-20 miles, often waived on 15+ ton orders

Figure quantities at about 1.4 tons per cubic yard of compacted base. A 12×50-foot driveway at 4 inches deep needs roughly 7.5 cubic yards — call it 10-11 tons — which lands around $180-$280 in recycled material versus $300-$450 in virgin stone. On a big rural drive the savings buy the plate compactor rental several times over. Many recycling yards also charge tipping fees to accept old concrete ($10-$40 per load), so if you are demoing a patio and building a base in the same season, one yard can handle both sides of the transaction.

Limitations and When to Buy Virgin Stone

Crushed concrete has a short list of honest drawbacks. Fresh RCA can leach alkaline runoff (pH 11-12) for its first months, which matters next to ponds, sensitive plantings, and some drainage codes. The re-cementing fines that make it a great base make it a mediocre decorative topping — it dusts white in dry weather and never has the washed, uniform look of pea gravel or granite. Quality control depends entirely on the yard, and stray brick or asphalt is common in cheaper mixes. And for exposed decorative work, drainage stone inside perforated-pipe systems where fines could clog fabric, or spec jobs that require certified virgin aggregate, buy new stone and be done with it.

Skip RCA, too, as the aggregate inside new structural concrete unless your mix designer specifically engineers for it — recycled aggregate absorbs more water and changes mix behavior. For a homeowner, its place is under and around concrete, not in it.

Crushed Concrete vs. Crushed Asphalt (RAP)

Recycling yards usually sell both, and they behave differently enough to matter. Recycled asphalt product (RAP) — milled-up old blacktop at $10-$25 per ton — binds in hot weather as its residual tar softens, packing into a darker, slightly tacky surface many people like for driveways. Crushed concrete binds through cement chemistry instead, cures harder over time, and stays inert in summer heat, but never gets RAP’s semi-paved look. Pick RAP when you want the driveway surface itself to feel closest to asphalt; pick crushed concrete when you want the strongest compacted base under something else, or a lighter color. Some yards sell a blend, which splits the difference for lane surfacing.

One more comparison worth pricing: in regions with cheap local quarries, virgin crusher-run limestone sometimes lands within a couple of dollars of RCA per ton, erasing the discount. Get quotes on both with delivery included — hauling distance, not the material, often decides the winner on any given address. As a rule, RCA holds its price advantage best within 20 miles of a metro recycling yard; deep rural addresses sometimes find the local quarry cheaper simply because the truck drives half as far.

Ordering and Installation Tips

Order by the ton from a recycling yard rather than by the bag; bagged anything costs 5-10 times bulk rates. Tell the yard the use — “compactable base” gets you the fines-included grade, “drainage” gets you clean stone — because names vary and the wrong screen ruins the job. Place material in lifts no thicker than 3 inches, wet each lift lightly, and compact with a plate compactor ($90-$110 per day rental) before the next. Crown driveways an inch or two to the center so water sheds, and let the surface cure through a few rain cycles before judging it: crushed concrete genuinely improves for its first month as the fines lock down. Done this way, a recycled base is not the budget compromise — it is the contractor’s pick that happens to cost less.

Two final field notes. Lay woven geotextile fabric ($0.15-$0.30 per square foot) under the base on soft or clay subgrades — it stops the expensive stone from slowly disappearing into the mud and can halve the depth of material a bad subgrade demands. And when a driveway needs topping up years later, order the same fines-included grade rather than clean decorative stone; new CA6-type material knits into the old crust within weeks, while a layer of washed gravel on top just skates around like marbles on a countertop.