Ordering the wrong quantity of ready mix concrete is one of the most common causes of delay and unnecessary cost that we see here at SRC Group. Order too little and you’re left waiting for a second load whilst the first pour starts to go off; order too much and you’re paying for concrete that you didn’t need, plus the cost of disposing of it. Getting the calculation right from the start can help you to keep on-track with both your timeline and budget. That’s why we’ve put together this ready mix concrete ordering guide.
The starting point for any ready mix concrete order is a simple volume calculation: length × width × depth, with all measurements in metres. This gives you a volume in cubic metres (m³), which is how ready mix concrete is ordered and priced.
For example, a slab measuring 5m long, 3m wide and 150mm (0.15m) deep, would need: 5 × 3 × 0.15 = 2.25m³.
At SRC Group we understand that getting your quantities right isn’t always straightforward, particularly when you’re dealing with several differently-shaped areas. If you’re unsure how much concrete you’ll need, our friendly team are always happy to help.
The above calculation is the theoretical volume of the finished pour but it’s not quite the amount that you should order. This is because ground is rarely completely level and formwork isn’t always perfectly sealed; some material may be lost to spillage and compaction as well as minor variations in depth. At SRC we always recommend ordering roughly 10% more than your calculated volume as a standard allowance.
Applying that to the example above, a 2.25m³ pour with a 10% allowance would mean ordering closer to 2.5m³, rounded up to account for any amounts that might be lost. As ready mix suppliers only deliver in specific volumes rather than exact fractional amounts, it’s always worth checking a supplier’s smallest deliverable load size when placing an order. For example, at SRC our smallest load would be 1.0m3.
A barrel mix is batched at one of our plants and delivered ready-to-pour, which works well for larger, continuous pours where the total volume has been calculated in advance and is unlikely to change. A volumetric mix on the other hand, is batched on-site from individual ingredients, meaning that the concrete can be mixed on-site according to the quantity required; helping to minimise waste on projects where the final volume is harder to predict, such as irregular groundworks or projects with restricted access.
If you’re working on a smaller or less predictable pour, it’s worth asking whether a volumetric mix is more suitable, since it can often reduce the risk of over-ordering altogether.
Even when the right quantity is calculated beforehand, a few common issues can still cause delays on delivery day.
Site access: Ready mix wagons are large vehicles and a standard load typically carries around 8m³ of concrete. Our drivers will need enough space to access the pour point and turn safely. If your site has restricted access, it’s worth discussing this with us in advance so that the right vehicle, or a volumetric mix, can be arranged.
Discharge time: Concrete hydrates from the moment that it’s batched and ordinarily needs to be discharged within around two hours, although this can vary depending on the mix and ambient temperatures. With the use of specialised additives, this can be increased to 8+ hours.
Make sure that your site is genuinely ready to receive concrete before it’s dispatched, not just before it arrives.
Ordering the wrong mix: Specifying the wrong mix reference, particularly for structural pours that need to meet a specific standard, can mean a load being rejected on-site. Double-checking your mix requirement against your project’s specification before ordering can avoid this entirely.
Unrealistic delivery windows: Booking a delivery slot that doesn’t account for site preparation time is one of the most common causes of on-site hold-ups that we see. Building in a buffer between site readiness and your requested delivery time can reduce the risk of the wagon arriving before you’re ready for it.
Where possible, we’d recommend placing your ready mix concrete order at least 24 hours in advance, though this may need to be longer if you require a larger pour or specialist mix. To avoid delays once your order is placed, it helps to have the following ready when you get in touch with the team:
Getting the Right Mix for Your Project
At SRC we supply a full range of ready mix concrete, including standard and high-strength mixes, as well as 5 low-carbon STRC options; available from all seven of our plants and compliant with BS8500-2 and NHBC specifications. Our low-carbon mixes also incorporate recycled aggregates covered by SRC’s Environmental Product Declaration (EPD), which provides independently-verified environmental data for the recycled materials used within the mix.
Get in Touch with SRC
Whether you’re calculating ready mix concrete quantities for a small DIY pour or planning concrete deliveries for a large commercial groundworks project, getting your order right from the start can help to keep things on-track. If you’re unsure about quantities, mix requirements, additives or delivery options, contact our friendly team to talk through your project or request a quote.
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