Crushed Concrete

Crushed concrete starts as demolished slabs, sidewalks, foundations, and pavement that gets run through a crusher and screened into graded sizes. Processors pass the material over magnets to pull out steel rebar, then screen it into grades ranging from fine crusher-run dust around 0-5mm up to 20-40mm base rock, with coarser 1-3 inch angular chunks kept separate for drainage or fill. This is where the fines versus washed distinction matters. Material sold with fines intact packs tighter and locks harder, which is exactly what you want under a driveway or paver patio. Washed crushed concrete has had the dust and fine particles rinsed out, leaving a cleaner, more open-graded product that drains faster but compacts less densely. If you are building a load-bearing base, ask for material with fines. If you need water to move through quickly, ask for washed. Because it comes from demolition sources rather than a quarry, quality varies by batch, so confirm the grade and source with your supplier before ordering.

Start by excavating to the depth needed, typically 4 to 8 inches for a driveway base, then grade and lightly compact the subgrade soil before adding material. Spread crushed concrete in lifts of no more than 3 to 4 inches, wetting lightly and running a plate compactor or roller over each lift before adding the next. Skipping this step and dumping the full depth at once is the most common reason bases fail, since uncompacted material shifts and ruts under load. For driveways or paver bases, crown or slope the surface slightly for runoff since the material sheds water well but still needs positive drainage. Once compacted, the surface should feel solid underfoot with no visible movement. If you plan to leave it as a finished driving surface rather than topping it with pavers or asphalt, expect to top-dress periodically as the surface wears and migrates from traffic.

Compared with limestone base (virgin crushed stone). Crushed concrete usually costs 30 to 50 percent less than comparable virgin limestone base and compacts just as well thanks to its angular shape and leftover cement paste. Limestone offers more uniform sizing and color since it is quarried, not demolished, so if visual consistency and predictable spec matter more than price, limestone wins.

Compared with decomposed granite or stone dust. Crushed concrete is a coarser, structural aggregate built for base and drainage work, not a finished walking surface. Decomposed granite and stone dust are fine, uniform-colored products chosen for smooth patios and paths. Use crushed concrete underneath, and a fines-based finish material on top if appearance matters.

How much crushed concrete do I need. Multiply length by width by depth in feet, then divide by 27 to get cubic yards. As a shortcut, one cubic yard covers about 108 sq ft at 3 inches deep or 81 sq ft at 4 inches deep. For tonnage, figure roughly 1.2 to 1.5 tons per cubic yard, though wetter or finer loads can run lighter or heavier. Always round up slightly to cover compaction loss and uneven subgrade.

How it is sold and delivered. Crushed concrete is sold by the cubic yard or by the ton, typically in bulk truckloads dropped at your driveway or job site rather than in bags. Grade and size should be specified at order time, whether that is fine crusher-run with fines for a compacted base, washed coarse material for drainage, or larger 1-3 inch chunks for fill. Minimum load sizes and exact grade names vary by supplier.