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Concrete 3D Printer FAQ

Q1: How to adjust the concrete mix ratio to ensure good interlayer adhesion?

For optimal interlayer bonding, use a mix with 30–35% sand, 15–20% cement, and a water-cement ratio of 0.35–0.4. Add 0.5–1% of PCE to improve fluidity without reducing strength. Test the extrusion consistency before printing; if layer separation occurs, increase the cement ratio by 2–3%.

Q2: How to calibrate extrusion pressure for large-scale concrete 3D printing?

Start with an initial pressure of 2–3 bar for small test prints, then adjust according to the layer height. For large-scale structural printing, increase the pressure to 4–5 bar to ensure full material filling, and monitor the first 3–5 layers to confirm uniform extrusion. Use the printer's built-in pressure sensor to maintain stability during long prints.

Q3: What key points should be noted when preparing concrete slurry for 3D printing?

Control the slump of the slurry at 6–8cm to balance pumpability and extrudability; compound PCE with a small amount of retarder and thickener to avoid rapid setting. Ensure the aggregate particle size is less than 5mm to prevent pipeline blockage, and stir the slurry continuously before printing to maintain uniform consistency.