Concrete-Printer Bonding Window Curve Explorer (2D)

Process Parameters

Print speed 20 mm/s

Layer height 20 mm

Cure rate 1.0×

Layer pause (time gap) 6 s

Readouts at current gap

Cure at gap

–

Joint quality

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Window (this curve)

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Wall integrity

100%

Good joints

Cold joints

Weak joints

Sim clock

0 s

Good bond — inside the window Cold joint — cured past open time Weak / bulging — deposited too soon

How the curve is built

This is the 3D Concrete-Printer Layer-Adhesion Timing Window model turned inside out: instead of running one animated print and reading off pass/fail, it plots adhesion strength as a function of the layer pause for whatever process settings you choose, so you can see the whole bonding window — and how it shifts — at once.

cure(gap) = 100 · (1 − e^(−gap/τ))
τ = 12 / cure_rate
σ (stability threshold) = clamp(30 · layerHeight/20 · (0.7 + 0.3·speed/20), 8, 60)
open-time threshold = 68% (fixed)

gap < σ-cure     → weak / bulging   (fresh weight lands before the layer can carry it)
σ ≤ cure ≤ 68%    → good bond
cure > 68%        → cold joint      (surface skinned over before the next bead landed)

Print speed — a faster nozzle pass finishes a layer sooner, but the extra deposition rate also adds a little more momentum load onto the layer underneath, nudging the stability threshold σ up.
Layer height — a taller bead is heavier, so the layer below needs more cure before it can carry it: σ scales directly with layer height.
Cure rate — sets how fast the concrete mix itself gains strength (the time constant τ); a faster-curing mix pulls the whole window toward shorter pauses.
Layer pause — the gap you actually choose between printing one layer and the next. Its marker slides along the curve below and drives the animated cross-section at the same time.

The bonding window is the pause range where the curve sits at 100% strength — wide and forgiving for thin, slow-cured layers, narrow and unforgiving for thick, fast-printed ones.

Print head Wet concrete Cured concrete

Wall cross-section

Printing layer 1

Adhesion strength vs. time gap