Mechanical Properties of 3D-Printed High-Ductility Cementitious Composite with Sulphoaluminate Cement and Modified Crumb Rubber (2025-06)¶

A novel high-ductility cementitious composite (HDCC) for 3D printing was developed by incorporating NaOH surface-modified CR as a sustainable aggregate replacement and polyethylene (PE) fibers, while substituting ordinary Portland cement with sulphoaluminate cement (SAC) and fly ash to minimize greenhouse gas emissions. The study systematically investigated the influence of modified CR and varying fiber volume fractions (FVFs) on the balance between printability and mechanical performance. The proposed 3D-printed HDCC was assessed for flowability and printability to determine the optimal mix proportions, followed by an evaluation of their mechanical properties, including compressive strength, flexural strength, tensile properties, bending strength, and interlayer/intralayer bonding strength. Experimental findings showed that all HDCC specimens, except for specimen RPE-1.5, were successfully printed. The compressive anisotropy coefficient was higher than the flexural anisotropy coefficients for all 3D-printed HDCC specimens, with specimen RPE-1.2 emerging as the optimal mixture. Increasing FVFs had a positive effect on tensile, bending, interlayer/intralayer bonding strengths of 3D-printed HDCC specimens, while decreasing the compressive strength. Additionally, the incorporation of CR resulted in an increase in the flexural, bending and tensile properties, and a slightly reduction compressive strength of 3D-printed HDCC specimens.