What makes a concrete mix hard to pump?

Stiff low-slump mixes, large or angular aggregate, and small pipe diameters all raise friction sharply. A wetter mix with rounded aggregate in larger pipe pumps with much lower line pressure for the same distance.

How is vertical lift handled?

Lifting fresh concrete adds static head of about 0.235 bar for every meter of rise, on top of friction. A tall pour can demand more pressure for the lift than for the entire horizontal run, so vertical distance matters a lot.

Why do bends add pressure loss?

Each direction change forces the concrete column to redirect, which behaves like extra pipe length. The tool adds roughly three meters of equivalent pipe per 90 degree bend, so a line with many bends loses noticeably more pressure.

Is this exact enough to size a pump?

It is a planning estimate that captures the right trends and magnitudes. For a critical or marginal pour, confirm against the pump manufacturer's pressure-versus-distance chart and the concrete supplier's pumpability data.

What is a typical pump rating?

Trailer pumps commonly develop 70 to 130 bar, while large boom pumps can exceed 200 bar. Always leave margin above the calculated requirement for pipe wear, mix variation, and to keep output up at the end of a long run.

What is the Concrete Pump Friction Loss Calculator?

Estimates the pressure a concrete pump must develop to push a mix through its delivery line, combining horizontal friction loss, bend losses, and vertical static head from slump, aggregate size, pipe diameter, and run lengths. Flags whether the pump's rated pressure is enough. It runs free in your browser on Gera Tools, with nothing uploaded.

Concrete Pump Friction Loss Calculator

Name: Concrete Pump Friction Loss Calculator
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Before a pour, you need to know whether your pump can actually push the mix to where it has to go. This calculator estimates the line pressure required by combining horizontal friction, bend losses, and the static head of lifting fresh concrete, then compares it against your pump’s rated pressure.

How it works

Total required pressure is the sum of three parts:

friction  = friction_gradient (bar/m) × horizontal_run
bends     = friction_gradient × (3 m per 90° bend × number_of_bends)
static    = 0.2354 bar/m × vertical_lift
total     = friction + bends + static

The friction gradient rises for stiffer low-slump mixes, larger aggregate, and smaller pipe. The static term comes from the density of fresh concrete, about 2400 kg/m³, which adds roughly 0.235 bar of head per meter of rise.

What the three components mean in practice

Horizontal friction is the dominant factor for long flat runs like basement floors or large ground-floor slabs. The friction gradient depends heavily on mix workability: a 75 mm slump mix in a 100 mm pipe creates much higher line pressure than a 150 mm slump mix in a 125 mm pipe over the same distance.

Bend losses matter most when the line has to navigate a building’s structure. Each 90° direction change behaves like adding roughly 3 metres of equivalent pipe length. A line threading through two floors with six bends adds the equivalent of an extra 18 metres of horizontal run. Reducing bend count by route-planning the hose path can meaningfully reduce peak pressure demand.

Static head from vertical lift is fixed by physics — approximately 0.235 bar per metre of rise regardless of pipe diameter or mix. For a 40-metre vertical pour on a high-rise structure, the static component alone is around 9.4 bar before any friction is added.

Worked example

A 125 mm slump, 20 mm aggregate mix pumped through 125 mm pipe:

Horizontal run: 50 m
Vertical lift: 20 m
Number of 90° bends: 4

Estimated friction gradient for that mix and pipe: approximately 0.06 bar/m

friction = 0.06 × 50 = 3.0 bar
bends    = 0.06 × (3 × 4) = 0.72 bar
static   = 0.235 × 20 = 4.7 bar
total    ≈ 8.4 bar

A trailer pump rated at 70 bar has more than enough capacity; even with a 30% pressure reserve for pipe wear and mix variation, 8.4 bar is well within range.

Tips for keeping pressure manageable

Keep slump in the pumpable range and use the largest practical pipe, minimize bends near the pump where pressure is highest, and place the pump as close as possible to the pour to keep horizontal runs short. Always plan a generous margin: pipe wears, mixes vary batch to batch, and you want full output at the far end of the line.