1. Effect of retarders on gypsum paste(a) Setting time vs content of retarder; (b) Fluidity vs content of citric acid (CA) in the gypsum paste; (c) Shear elastic modulus vs shear stress; (d) Yield stress vs content of CA

2. Effect of thickener on gypsum paste(a) Setting time vs content of thickeners; (b) Fluidity vs content of thickener; (c) Shear modulus of elasticity of HPMC with different dosage; (d) Yield stress vs content of HPMC

3. Structures and microstructures of printed 3D gypsum(a, d) Scaffold structure with three horizontal lines and three vertical lines appearing alternately and periodically in the Z-axis, the cross angle is 60°; (b, e) Spider structure consisting of alternate layers of radial and circular rods; (c, f) Scaffold structure with three horizontal lines and three vertical lines appearing alternately and periodically in the Z-axis, the cross angle is 45°; (g-i) Microstructure of printed gypsum parts

4. Compressive strength of different gypsum samples3 Discussion

5. XRD patterns at different hydration time for gypsum pastes with different agents(a) 0.6% (in mass) citric acid gypsum at different hydration time; (b) 0.6% (in mass) citric acid and 0.3% (in mass) HPMC at different hydration time

6. SEM images of gypsum at different hydration time(a-d) Gypsum with 0.6% (in mass) CA at different hydration time ((a) 5 min, (b) 12 min, (c) 20 min, (d) 300 min (final setting time)); (e-f) Gypsum with 0.6% (in mass) CA and 0.3% (in mass) HPMC at different hydration time ((e) 5 min, (f) 12 min, (g) 20 min, (h) 320 min (final setting time))