Effects of mixing and grinding methods on the dispersion and physicochemical properties of calcium silicate/polyethylene glycol composites

PEG-400 was employed as a dispersing medium. Three processing methods were compared to examine their effects on the dispersion behavior of C₃S suspensions. Planetary ball milling exhibited the most optimal dispersion performance. After 50 h of standing, no visible sedimentation was observed; the amalgamator and benchtop ball-milled samples exhibited obvious settling. The planetary ball-milled sample had an average particle size of 236.2 ± 11.5 nm, a PDI of 0.126, and a zeta potential of 52.94 ± 5.55 mV. The XRD analysis confirms that all processing methods preserved the crystalline phases of C₃S. Optimizing the planetary ball milling elicited 450 rpm for 4 h as the optimal condition, demonstrating the smallest particle size (197.5 ± 12.9 nm), the lowest PDI (0.038), and the highest zeta potential (60.12 mV). Long-term sedimentation tests indicate that suspensions prepared at ≥450 rpm remained suspended without noticeable sedimentation after three months of storage. Functional validation of the optimized formulation showed a final setting time of 24 h and compressive strengths of 9.004 ± 0.823 MPa and 11.003 ± 1.760 MPa after 7 and 28 days of immersion, respectively. The material also exhibited antibacterial activity against Enterococcus faecalis, Staphylococcus aureus, and Escherichia coli, with inhibition zone diameters ranging from 4.3 ± 0.6 to 7.2 ± 0.3 mm. The results establish a clear processing-structure-property relationship in C₃S/PEG suspensions. These findings indicate that optimized planetary ball milling enhances particle deagglomeration, interfacial homogeneity, suspension stability, mechanical performance, and antibacterial functionality.