Across the ready-mix industry, an estimated 1 to 5 percent of all concrete produced, and in some cases as much as 10 percent, comes back to the plant as returned concrete. NRMCA surveys find that less than 1 percent of those returns are due to quality or specification problems, which means the overwhelming majority is simply over-ordering by the customer.
For a hardscaper, that over-order turns into the worst jobsite outcome: a wheelbarrow of leftover concrete setting up on a client’s brand-new lawn, or a returned-concrete charge on the bill. The fix is pay-for-what-you-pour metered (volumetric) supply. It batches on site and meters to the quarter-yard, so you re-estimate near the end of the pour and shut it off when the forms are full. You pay only for what actually went down, with no leftover pile and no returned-concrete charge.
This article is about the waste and the economics of over-ordering, not about cracking or scaling. For whether decorative concrete cracks in a Calgary winter, see the freeze-thaw article. For estimating your yardage in the first place, see the how-much-concrete article.
How much concrete actually gets wasted?
More than the industry likes to admit, and almost all of it for one reason.
The clearest source is NRMCA’s technical note on returned concrete. In its words, “Estimates of returned concrete from producers vary from 1 to 5%, and in some cases as high as 10%, of the volume produced at the plant.” Then the part that matters most: “Based on NRMCA surveys, the volume of returned concrete due to inadequate quality or specification non-compliance is less than 1%. This suggests that most of the returned concrete results from over-ordering by the purchaser.” (Source: NRMCA TIP-19, “Reuse of Returned Concrete”.)
Read that again. The concrete isn’t coming back because it failed a test. It’s coming back because someone ordered more than the job used.
Independent waste research points the same way. A study of ready-mixed concrete waste found that over-ordering accounts for the majority of leftover volume, alongside the often-cited industry figure of roughly 5 percent of production returned. (Source: ScienceDirect, “Waste generation from the production of ready-mixed concrete”; the abstract is paywalled, so re-verify the exact percentage at refresh.)
NRMCA also notes a wrinkle that lands close to home: “Higher return volumes are often reported at plants with smaller footprints in urban areas.” Urban Calgary hardscape jobs, served by urban plants, sit squarely in that profile.
Why do contractors over-order in the first place?
Because running short is worse than running over, on most jobs.
If a drum truck empties before the forms are full and the first concrete sets before a top-up arrives, you get a cold joint, a weak seam where two pours didn’t bond. So the trained instinct is to pad the order. The trouble is that with a fixed truckload, the padding has nowhere to go. It becomes a pile on the lawn or a line item on the invoice.
There’s a real habit underneath this, and it’s not wrong for every material. Paver-base guidance actively tells installers to over-order. Inch Calculator advises estimating “an additional 20% of material so that when compacted, it reaches the correct depth” for the gravel base, plus a “5–15% waste factor depending on pattern complexity” for the pavers, and to round up to avoid running short.
(Sources: Inch Calculator paver base; Western Interlock; Unilock.)
That advice is sound for crushed gravel. Compaction really does eat 20 percent, and a loose paver here or there is cheap. But the same instinct applied to the concrete elements, the footings, slab bases, and step cores, is what creates the leftover pile. The fix isn’t to stop over-ordering everything. It’s to over-order the gravel and meter the concrete.
What does over-ordering cost?
Two ways: the concrete you paid for and didn’t use, and a charge for sending it back.
Plant price lists bill returned concrete directly. One Ontario list (Dufferin) charges unused concrete at $50.00 per cubic metre.
(Source: Dufferin 2025 price list, p.5; Ontario, validate Calgary quotes.)
So padding an order by a single cubic metre “to be safe” can cost about $50 in a return charge on top of the wasted material itself. For the full fee math, see the short-load-fee article rather than re-running the tiers here.
Then there’s the cost that doesn’t show on an invoice. A leftover pile setting up on a new lawn is a reputational mark on a premium job, and disposing of returned concrete is a genuine industry sustainability problem, ending up in windrows or landfill or recycled into aggregate. NRMCA’s note lists those disposal routes precisely because none of them is free or clean. Ordering the exact amount is the cleanest waste avoidance there is.
(Source: NRMCA TIP-19.)
How do you pour with zero leftover?
You meter it, and you re-estimate at the end. That’s exactly NRMCA’s own mitigation advice: “customers should be requested to re-estimate volume of concrete required towards the end of the placement.”
(Source: NRMCA TIP-19.)
With a fixed truckload you can’t act on that advice, because the concrete is already mixed and on the truck. With a metered volumetric mixer you can, because nothing is batched until it’s discharged. The truck carries cement, sand, stone, and water separately and meters them to the quarter-yard, so as the forms fill you re-estimate, top up the last bit, and shut it off. There’s no pile and nothing to send back. A real Alberta small-load policy states it plainly: “NO CHARGE FOR RETURN OF LEFTOVER CONCRETE,” because there’s nothing to return.
(Source: Mini Batch price list, Edmonton-area, not Omega’s price.)
There’s a phased-pour bonus for hardscapers too. Hardscape volumes are uncertain until you’re building, often spread across days or weeks: footings this week, a wall next, steps after. Metered on-site supply lets you mix exactly what each element needs, when you’re ready, without pre-booking and padding a single large order. That flexibility is its own waste reducer, though it’s a separate topic from the leftover thesis here.
Metered concrete is especially valuable on projects where you’re pouring footings or pads before installing precast elements. If you’re replacing exterior stairs, see How precast concrete steps are made—and set at your Calgary entry in a single morning to understand how a precast installation minimizes site work, reduces concrete waste, and often completes the entire replacement in a single day.
Should I over-order my paver base too?
Yes for the gravel, no for the concrete. Keep the two separate in your head and on your order.
- Gravel base: over-order about 20 percent, because compaction pulls the loose depth down to the finished depth.
- Pavers: add a 5 to 15 percent waste factor for cuts and pattern complexity.
- Concrete elements (footings, slab bases, step cores): meter them. Don’t pad a concrete order the way you’d pad gravel, because concrete you don’t pour becomes a pile or a charge.
That single distinction, over-order the gravel and meter the concrete, is the practical heart of a zero-leftover jobsite.
The clean-jobsite payoff
For a premium-residential hardscaper, the leftover pile is more than a cost. It’s a finish-quality signal in the wrong direction. A clean jobsite is something the client notices, especially on a new acreage lawn where a setting-up pile is impossible to hide. Metering the concrete protects the lawn, the bill, and the reputation in one move.
Calgary’s freeze-thaw climate adds a final reason to clear the site cleanly: a broken-up leftover pile left behind becomes site debris that weathers through the same cycles as everything else. For whether the finished hardscape itself survives those cycles, that’s the freeze-thaw article’s job, linked below.
FAQ
How much concrete gets wasted by over-ordering? Industry returns run about 1 to 5 percent of production, and sometimes up to 10 percent. NRMCA finds most of it is over-ordering, since less than 1 percent of returns are quality or spec problems.
Why do contractors over-order concrete? To avoid running short mid-pour and creating a cold joint. With a fixed truckload, though, the padding becomes a leftover pile or a returned-concrete charge.
What is a returned-concrete charge? A per-cubic-metre fee for unused concrete sent back to the plant, such as $50 per cubic metre on one Ontario list. Validate against current Calgary quotes.
How do I avoid a leftover concrete pile on the lawn? Meter the pour. Re-estimate near the end and shut off when the forms are full. Metered volumetric supply bills only for what you discharge, so there’s nothing left over.
Should I over-order my paver base too? Over-order the gravel base by about 20 percent for compaction and the pavers by 5 to 15 percent for waste, but meter the concrete elements so there’s no leftover.
Does volumetric concrete have a return charge? No. You pay for the metered yards you discharge, so there’s nothing to send back and nothing to charge for.
Why are urban Calgary jobs more prone to leftover problems? NRMCA reports higher return volumes at plants with smaller footprints in urban areas, which is the profile of many urban Calgary hardscape jobs.
