Volumetric / On-Site Mixed Concrete in Kent

The lorry is a mobile batching plant. Raw materials travel in their own bins, and the mix is metered and combined through an auger at the back of the vehicle as it is discharged. Nothing is mixed until it is asked for.

That single difference drives everything else about volumetric. There is no batch sitting in a drum from the moment it leaves a plant, so the working life of the concrete starts when it is made, on your site, in front of you.

Paying for what you use

Because the material is only mixed as it comes out, the quantity is settled at the end of the pour rather than at the start of it. You take what the job turns out to need.

That is what most of our approved suppliers mean by a pay-for-what-you-use basis, and it is the reason volumetric suits jobs where the volume is genuinely unknown until the pour is under way. An irregular excavation, a trench that has been dug wider in places, a void of unknown size, a levelling pour over uneven ground: none of these can be measured accurately in advance, and all of them are awkward to order as a fixed load.

Changing the mix without leaving site

A volumetric lorry can change what it is producing between one part of a pour and the next, because the ingredients are still separate. That covers the jobs where one visit has to do two things: a stiffer mix for a haunching and a flowing one for the trench, or a lean fill under a slab and a stronger mix in the slab itself.

That flexibility is in the vehicle, not in the specification. Where a designation is specified, by an engineer, on a drawing, or by building control, that is what gets batched, and a mix change during a pour should be a change between two designations that were both settled before the lorry arrived.

Is volumetric concrete BS 8500 compliant?

It can be, and what decides it is the producer rather than the mixer. BS 8500 and BS EN 206 are the standards concrete is specified and supplied against in the UK, and neither is a specification for a type of vehicle. The two UK certification schemes that sit behind them, QSRMC and the BSI Kitemark scheme for ready-mixed concrete, each state that their scope covers mobile batching vehicles as well as static plants.

The gate is certification. The designated concretes under BS 8500, the GEN, RC, FND and PAV families, are supplied on the strength of third-party product conformity certification held by the producer. A volumetric operator that holds it can supply them. One that does not cannot, and neither can a static plant without it. A producer without certification is working to the standardised prescribed mixes, the ST range, which are made to fixed proportions rather than to a performance requirement.

So the useful question is not whether the concrete is volumetric. It is whether the supplier is certified, and for which mixes. Kent Readymix passes that question to the approved supplier when you tell us the pour needs a specific designation, and you should ask for the designation to be confirmed and recorded on the delivery ticket.

That ticket is your record of what went into the ground. It is the document a building control officer would want during construction and a surveyor might ask for years later, and it is worth keeping with the rest of the paperwork for the job.

What changed for volumetric mixers, and what did not

The rules that changed for volumetric mixers between 2017 and 2018 were transport rules. The exemptions these vehicles held from annual testing and from operator licensing were removed, and a timetable was set for their weight limits to fall into line with other heavy goods vehicles.

Those are vehicle and haulage regulations. They did not change how concrete is specified, how a mix is designated, or how a producer demonstrates conformity. The two are worth keeping apart, because the change is often repeated second-hand as though it had been a judgement on the concrete, and it was not.

When volumetric is the right choice, and when it is not

Volumetric earns its place where the quantity is uncertain, where the mix needs to change, where a pour is spread across a long working period, or where a small overrun would otherwise mean ordering a second load.

It is not automatically the right answer. A large, well-defined, continuous pour with a known volume is normally better served by a drum mixer, sometimes by several in sequence, because the delivery rate is higher and the pour finishes sooner. Where a floor or a raft has to go in as one continuous placement, rate of supply matters more than flexibility. Kent Readymix will say which of the two suits the pour you describe rather than defaulting to one.

What a volumetric lorry needs from your site

A volumetric mixer is a large vehicle carrying its materials as well as its plant, and it is neither small nor light. It needs a firm standing, room to position, and clearance to work the discharge chute.

The practical checks are the ones you would make for any heavy vehicle: the width of the approach, overhead cables and branches, the load-bearing capacity of a private drive, and whether there is a soakaway, an inspection chamber or a septic tank in the ground it would stand on. Give us that detail with the enquiry and an approved supplier can confirm whether their vehicle fits before anyone commits to a date.

Volumetric and the delivery window

Many of our approved suppliers can deliver next day, and for commercial customers on an agreed contract, delivery within hours is sometimes possible depending on location and availability.

Your approved supplier confirms the window, because it depends on where the nearest available vehicle is and what else it is booked to do that day. Your quotation, delivery and payment are agreed directly with the approved supplier appointed to your pour.

Arranging on-site mixed concrete

Tell us what you are pouring, your best estimate of the volume, how confident you are in that estimate, and where the lorry could stand. The uncertainty is useful information here rather than a problem: it is the reason volumetric exists.

Where the volume is firm and the pour is large, we will say so and quote a standard delivery instead.