Influence of Printing Speed and Extrusion Speed on the Performance and Pore Structures of 3D Printed Mortar (2025-08)¶

This paper investigates the influence of printing speed and extrusion speed on the early-age properties (green strength and 24-h shrinkage), mechanical strength (flexure strength, compressive strength, and bond strength), chloride penetration resistance, and pore structure of 3D-printed mortar. Single-factor experiments determined optimal parameters, with a printing speed of 50–75 mm/s and an extrusion speed of 0.25–0.35 r/s identified as optimal. The study also analyzed the effects of parameter variations. As the printing speed increases, the printing material transitions from overlapping to a wavy pattern, decreasing strength, particularly when the speed exceeds 75 mm/s. Conversely, an increase in extrusion speed enlarges the printed material's width and height, enhancing strength. The pore characteristics of typical specimens were analyzed by CT scanning. To evaluate printing quality, the unit length extrusion mass D was introduced. When D reaches within an appropriate range (≥75 g/cm), the material's internal structure becomes denser, and the printed specimen achieves optimal width and height. Consequently, the material exhibits superior strength, reduced 24-h shrinkage, and improved resistance to chloride penetration.