August 6, 2026

What Is Volumetric Concrete and How Does It Work?

Most people picture a rotating drum on the back of a lorry when they think of concrete delivery. Volumetric concrete works differently. Instead of mixing the concrete at a plant and driving it to site, a volumetric mixer carries all the raw materials separately and mixes them fresh on arrival. The result is concrete that is always the right consistency, always the right volume, and never at risk of going off in transit. It is a smarter way to get concrete where it needs to go, and once you understand how it works, the difference is hard to ignore.

What Is Volumetric Concrete?

Volumetric concrete is concrete that is batched and mixed on site rather than at a plant. Understanding what that means in practice starts with how the truck is built and how it differs from the traditional approach.

The mixer truck carries separate compartments for aggregate, cement, water, and any additives, and combines them at the point of delivery using a continuous mixing auger. The operator controls the output in real time, which means the volume, mix grade, and consistency can all be adjusted during the pour if conditions change.

How It Differs From Traditional Delivery

Traditional ready-mix concrete is produced at a batching plant, loaded into a drum, and delivered within a fixed time window before it becomes unusable. The drum keeps the mix moving during transit, but the clock starts the moment it leaves the plant.

Volumetric concrete has no clock running before it arrives. The materials travel separately and are only combined when the truck is on site and ready to pour. This removes the risk of the concrete arriving too stiff, too wet, or already partially set, which is a real problem with plant-mixed deliveries when journey times are unpredictable.

What the Truck Carries

Volumetric mixers are large vehicles fitted with separate storage bays for each raw material. On arrival, everything feeds into a single mixing chamber:

Sand and coarse aggregate stored in separate compartments at the rear
Cement held in a sealed silo to prevent moisture getting in during transit
Water in a tank with a metered feed into the auger
Additives such as fibres, plasticisers, or accelerators in separate compartments

The operator controls all of this from a panel at the rear of the truck, adjusting the ratios and output rate as the job requires.

How Does Volumetric Concrete Work?

The process runs in five clear stages, from loading at the depot to cleanup after the pour. Each stage is straightforward, and together they explain why the finished product is consistently fresh regardless of how long the journey takes.

Loading at the Depot

Before the truck leaves the yard, each compartment is filled to the quantity specified in the order:

Aggregate bays loaded with sand and coarse stone to the required mix proportions
Cement silo filled and sealed to keep moisture out during transit
Water tank filled and set to the metered rate for the specified mix
Any additives such as fibres, plasticisers, or accelerators loaded into their own compartments

Nothing is mixed at this stage. Loading is simply a matter of getting the right amount of each ingredient on board.

In Transit

Nothing is mixed while the truck is on the road. The raw materials sit in their individual compartments throughout the journey. Whether the truck takes ten minutes or two hours to reach the site, the materials arrive in the same condition they left in. This is the key practical difference between volumetric and plant-mixed delivery.

Mixing on Site

When the truck is in position at the pour point, the operator activates the conveyor and auger system. The materials move from their compartments into the mixing chamber in the correct ratios, producing fresh concrete mix that flows directly to the chute.

The operator monitors the mix as it comes out and can adjust on the spot if needed:

Consistency can be loosened or stiffened by changing the water ratio
Output rate can be slowed to match the pace of the pour team
The mix grade can be changed if site requirements shift during the job

Controlling the Volume

Precision is one of the strongest practical advantages of volumetric delivery. Here is how the volume control works in practice:

The operator produces concrete continuously until the required volume is reached
If more is needed during the pour, production simply continues
If less is used than estimated, the auger stops, and unused raw materials return to the depot
The truck returns with dry materials rather than wasted mixed concrete

This also means there is no fixed minimum order. You pay for what you use, which makes volumetric delivery practical for small jobs where a traditional plant load would mean ordering far more than you need.

Not sure how much concrete your job requires? A quick call with the Pro-Mix Concrete team can help you estimate the volume so nothing is wasted and nothing runs short. Get a Volume Estimate for Your Pour today.

Adjusting the Mix During the Pour

If site conditions require a different consistency or strength partway through the pour, the operator can adjust the ratios on the spot. The mix can be made stiffer or slacker, stronger or lighter, without stopping the job. This flexibility is useful on complex pours where different sections may have different requirements, or where the weather or subgrade conditions change unexpectedly during the work.

What Happens After the Pour?

The process does not end when the last of the concrete leaves the chute. There are a few quick steps that wrap the job up cleanly and get the truck ready for the next delivery.

Once the required volume has been delivered, the operator stops the auger. What happens next:

Unused raw materials stay in their compartments and return to the depot for future use
The chute and auger are cleaned on site before the truck moves off
No hardening concrete needs to be washed out of a drum

There is no wasted mix to dispose of and no need to rush the cleanup against a time deadline as the mix sets. The whole process from arrival to departure is typically faster and cleaner than managing a traditional drum mixer when exact volumes matter.

Is volumetric concrete the same quality as plant-mixed concrete?

Yes, the raw materials are identical and mix designs apply. Volumetric concrete meets the same standards as plant-batched concrete. The difference is in the process rather than the quality of the finished product.

Can volumetric mixers produce any mix grade?

Most standard grades from Gen 0 through to C40 and beyond can be produced on a volumetric mixer, along with fibre-reinforced and rapid-setting options. The supplier will confirm what is available for a specific application before the order is placed.

Is there a minimum order?

No, because only the volume needed is mixed, there is no fixed minimum. You can order as little as a quarter of a cubic metre, which makes volumetric concrete practical for small residential jobs where a traditional plant load would result in significant waste.

Can the mix be changed during a pour?

Yes, the operator can adjust ratios and consistency in real time throughout the pour. This is one of the features that sets volumetric delivery apart from plant-mixed concrete, where the mix is fixed from the moment it leaves the batching plant.

Takeaway

Volumetric concrete works by keeping the raw materials separate until the truck is on site and the pour is ready to begin. That single difference removes the time pressure of traditional delivery, eliminates waste from ordering too much, and gives the operator real control over the mix right up to the end of the job. For projects where precision, flexibility, and fresh concrete matter, it is the more reliable option.

Pro-Mix Concrete operates volumetric mixers across London and the surrounding areas, delivering fresh concrete to the exact specification and volume required for residential and commercial projects of all sizes. Every load is mixed on site, so what arrives is always fresh, always the right grade, and always the exact volume ordered with nothing wasted. If the job is a small garden base or a larger structural pour, the team can advise on the right mix and confirm availability for your postcode.

Get in touch to discuss your project and get a quote.

Author

Dennis Broderick

Dennis Broderick is the founder and owner of Pro-Mix Concrete Company, a trusted name in ready-mix concrete solutions across the UK. With over 20 years of hands-on experience in the construction and concrete industry, Dennis brings unmatched expertise, practical insights, and a commitment to quality on every project - from residential driveways to large-scale commercial developments.

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