Development of Sustainable 3D Printing Concrete Materials (2025-09)¶

This study examined nine natural mineral derivatives and industrial/agricultural wastes available in Taiwan: silica fume (SF), fly ash (FA), blast-furnace slag (BF), limestone powder (LP), metakaolin (MK), paper sludge fly ash (PSFA), reactive ultra-fine fly ash (RUFA), oyster shell powder (OSP), and calcium sulfate whisker (CSW). Their effects on 3D printing concrete matrices with 30% cement replacement were evaluated by measuring rheological parameters (static yield stress, dynamic yield stress, plastic viscosity, viscosity recovery) and compressive strength. Results showed that materials with hydraulic activity and fine particle size (SF, MK, RUFA, PSFA) enhanced printability without reducing strength, increasing static yield stress by 30%–61%. FA and BF, with larger particle size, caused no adverse effects, whereas inert materials (LP, OSP, CSW) weakened rheology, reducing static yield stress by 36%–46%. At 30% replacement, SF, MK, RUFA, FA, and BF maintained strength and showed optimal potential for application at levels ≤30%, ensuring print quality while improving environmental benefits. Notably, SF, FA, and BF remained effective at up to 60% replacement, with all mixtures maintaining height loss within 0%–4% and tanθ within 0–0.09, confirming excellent printability and minimal structural deformation.