A broken-up slab looks harmless in a pile. It is not: broken concrete weighs about one ton per cubic yard — the same order as soil, far above a renovation dumpster that fills with wood and drywall. That is why concrete never goes into the renovation box, and why the rental is not billed by volume.
One size goes out: the 20 yard. The price covers 7 tons included, 12 tons maximum; each additional ton is prorated from the disposal facility's weigh ticket — real weight, never rounded. And the box fills three quarters at most (45 inches from the floor): the truck's legal load is reached well before the rim. Our drivers say it on every jobsite — a concrete dumpster filled to the brim would never leave your driveway.
What derails a concrete load is not the weight — it is drywall. Gypsum is calcium sulfate, and the City of Montreal caps water-soluble sulfate in recycled concrete at 0.20% where the aggregate will sit against concrete, 0.60% elsewhere. A few broken sheets in the bin are enough to downgrade the trip. Concrete also carries a signature neither brick nor asphalt has: a high pH, from the hydroxyl ions in cement paste — water running through a pile of crushed concrete comes out alkaline, and that is what governs how it is stored. Crushed, your concrete becomes a recycled granular material graded by its concrete content, and it goes back into road and sidewalk foundations. It does not become structural concrete again.