3D Printing of cement composites

The aims of this study were to investigate the feasibility of generating three-dimensional (3D) structures directly in rapid hardening Portland cement (RHPC) using 3D printing (3DP) technology. 3DP is an additive layer manufacturing (ALM) process that generates parts directly from CAD in a layer-wise manner. Three-dimensional structures were successfully printed using a polyvinylalcohol/RHPC ratio of 3:97 w/w, with print resolutions of better than 1 mm. The test components demonstrated the manufacture of features, including off-axis holes, overhangs/undercuts, etc. that would not be manufacturable using simple mould tools. Samples hardened by 1 day post-build immersion in water at RT offered modulus of rupture (MOR) values of up to 0·8±0·1 MPa, and, after 26 days immersion in water at RT, offered MOR values of 2·2±0·2 MPa, similar to bassanite based materials more typically used in 3DP (1-3 MPa). Post-curing by water immersion restructured the structure, removing the layering typical of ALM processes, and infilling porosity.