Choosing the method

Self-Loading Mixer, or Truck Mixer and Pump?

Two contractors on the same road package can pay very different prices for the same cubic metre of concrete, and the machine is rarely the reason. What separates them is how many cubic metres each machine places in a day, how many people stand around while it does, and what happens when the pour turns out to be fifteen cubic metres instead of sixty.

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The principle

The short answer: two numbers decide it

The cost of placing concrete, as opposed to the cost of buying it, behaves like this:

cost per m³ = (fixed cost of one working day ÷ m³ placed that day) + variable cost per m³

The fixed part is where the two methods diverge. A pump crew has to be mobilised, set up, primed and stood down whether you pour 20 m³ or 200. A self-loading mixer has almost no fixed cost outside its own working day: it drives up, loads, mixes and discharges from the same seat, and if the pour is smaller than expected it simply makes fewer batches.

So the pump's cost per cubic metre is nearly flat and falls slowly, while the mixer's falls steeply as the daily volume rises. Above a certain volume the pump's efficiency wins outright. Below it, the pump crew is being paid to stand next to a pour that is too small to carry them.

One caution before the numbers: if you buy ready-mix instead of batching on site, the delivered price already bundles the plant's buying power and its labour. That is a materials question, not a placing question, and it has to be compared on its own line. Everything below is about placing.

Side by side

Where the two methods actually differ

 Self-loading mixerTruck mixer + pump
People on site1 operator, plus 1 at the chute4–6: driver, pump operator, two or three on the hose
Set-up at each pourNone — drive up and discharge1–2 hours to position, set outriggers, prime the line
Practical output80–190 m³ in 10 hours150–300 m³ in 10 hours
Smallest pour that makes senseOne batch, 2.6–4.5 m³Often 30–60 m³ before the mobilisation is worth it
AccessChassis 2.8–3.1 m wide, 35° gradability6 m truck plus pump standing area plus a route for the line
When the pour is half a loadBatch fewer buckets — nothing is wastedPart-load premium, or a returned load and a cold joint
When the ground is softLoaded chassis around 9 tonnes26 tonnes plus outriggers — sometimes it cannot reach at all
MaterialsYou buy aggregate and bagged cement yourselfDelivered concrete, priced per m³ with a minimum per truck

Only two of these rows are about money in the ordinary sense. The rest are about time: the hour spent setting up a pump is an hour of payroll, and a returned load is a day of someone else's schedule.

The arithmetic

At what volume does the pump take over?

Strip it to the smallest honest form. Let D be what the self-loading machine costs you per working day — depreciation, maintenance, insurance, finance — and w one operator's daily wage. Let R be the pump crew's day rate including mobilisation and the four or five men on it.

If both were placing the same number of cubic metres, the mixer would be cheaper whenever D + w < R. But they are not placing the same number, so the comparison has to be made at each machine's own output. In practice that means one question: how many cubic metres will this site actually take, per day, for the next three months?

Daily volume, one siteWhat dominates the billWhich method usually wins
Under 40 m³, spread over several locationsMobilisation and per-pour fixed costSelf-loading mixer — one machine, no set-up
40–120 m³, one site, haul under 3 kmCrew size and cycle timeSelf-loading mixer; close if the haul is long
120–250 m³, one siteWhether the pump is fully utilisedDepends on the number of pours per week
Over 250 m³, continuousPlant efficiency per m³Ready-mix and pump

The trap in the third row is a pump that is booked for a full day and used for four hours. A pump on standby is the most expensive equipment on any site, because it bills by the day and produces nothing. Contractors who pour three or four times a week often find that a self-loading mixer at two-thirds of the pump's daily output is the cheaper machine, simply because it is never on standby.

Longmai self-loading concrete mixer travelling on a rural road with the drum turning

The haul is a cost line, not a detail. Every extra kilometre is four to six minutes of the cycle, and the drum keeps turning while you pay for it.

Hidden lines

Five costs that never appear in the quote

None of this argues that a pump is a bad machine. It argues that the pump's day rate is only the visible half of the pump's cost, and that comparisons built on the visible half flatter the pump and then disappoint.

The honest other side

When the pump is the cheaper answer

Four situations, and they are common enough that we would rather name them than talk around them:

Outside those four, the deciding factor is almost always the number of separate pours per week — not the size of any one of them.

Your own numbers

Six questions, ten minutes, one answer

Write these down before you talk to either supplier. Any quotation that cannot be read against all six is not a comparison.

QuestionWhy it changes the answer
How many m³ per day, on the busiest week?Sets the fixed cost per m³ for whichever machine you choose
How many separate pours per week?Each pour carries a fixed cost of its own; this is the number that kills pumps
What is the longest one-way haul?4–6 minutes per kilometre of cycle time, for the mixer
What is the narrowest point on the access road?Decides whether a 6 m truck can reach the pour at all
Who supplies cement and aggregate, and at what price?The materials line, which is separate from placing and often larger
What does a day of delay cost you?The line that never appears in either quote, and usually the biggest one

If your answers sit in the 30–150 m³ a day range, spread across more than one location, the arithmetic will point at a self-loading machine long before it points at a pump. If they sit above 250 m³ on one site, it will point the other way — and we will tell you so.

FAQ

Questions this article usually raises

Is a self-loading mixer cheaper per m³ than ready-mix concrete?

Not necessarily, and it depends on what you are comparing. Site-batched concrete avoids the part-load premium, the minimum order and the delivery charge, but you buy cement in bags at retail rather than in bulk. On small and scattered pours the site-batched route usually wins; on one large site with a plant nearby, ready-mix generally wins on materials.

How many people does each method need?

A self-loading mixer needs one operator, plus one man at the chute. A truck mixer with a pump needs four to six: the driver, the pump operator and two or three on the hose. Labour is often the single largest line in the placing cost, which is why this row matters more than the machine price.

What is the smallest pour that justifies a pump?

It varies with the local pump market, but as a rule of thumb, below 30–60 m³ the mobilisation and the minimum charge dominate, and a pump stops being economical. A self-loading mixer places a single 3.5 m³ batch without any set-up cost at all.

Should I buy the machine or hire one?

Buy if you will work it more than about 120 days a year and can keep a stockpile within reach of the pour points. Hire if the work is seasonal and concentrated in one place. The crossover is about utilisation, not about the purchase price — an idle machine costs the same per day whether it is owned or rented.

What about fuel?

Fuel is a variable cost and it scales with cubic metres, so it rarely decides between the two methods. It does decide between models: a 4.5 m³ drum burns more per hour than a 2.6 m³ one, but it carries more per cycle. Per cubic metre the difference is smaller than most buyers expect.

Next step

Send us three numbers — cubic metres per day on your busiest week, the number of separate pours, and the longest haul — and we will tell you which method the arithmetic favours. If that turns out to be a pump and a plant, we will say so; we would rather lose a quotation than sell a machine into the wrong site.

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Read next

How to choose a self-loading mixer size →  Four questions in the right order: road width, haul distance, discharge height, then cubic metres.

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