Determining the effect of superabsorbent polymers, macrofibers, and resting time on the rheological properties of cement mortar using analysis of variance (ANOVA): A 3D printing perspective

This study aims to analyze the effect of SAP dosage, presence of macrofibers, and resting time on the rheological properties of cement mortar. Accordingly, we measured the static yield stress, equilibrium shear stress, thixotropic area, and nonlinearity (shear thinning/thickening) using a rheometer, and analysis of variance (ANOVA) was utilized to statistically analyze whether each factor (explanatory variable) has any effect on rheological properties (response variable) at the 95% confidence level. The results demonstrated that while equilibrium shear stress and thixotropic area are influenced by SAP dosage, presence of macrofibers, and resting time at a statistically significant level, static yield stress is influenced by SAP dosage and resting time. In contrast, material nonlinearity is only influenced by SAP dosage at a statistically significant level. In addition, statistical models for the rheological properties of cement mortar with SAP and macrofibers were proposed using only the factors selected by ANOVA. The prediction models were found to have a high R² of more than 0.9 on average, excluding nonlinearity. The findings of this study can serve as basic data for determining suitable mixtures for 3D printing concrete incorporating SAP and macrofibers.