Effects of CaCO_3 whisker, hybrid fiber content and size on uniaxial compressive behavior of cementitious composites

摘要

Introduction of hybrid fiber and calcium carbonate (CaCO3) whisker could improve the properties of cementitious composites. Nevertheless, little attention has been paid to influences of steel-polyvinyl alcohol (PVA) hybrid fiber and whisker on stress-strain behavior of hybrid fiber reinforced cementitious composites (HFRCC). In this research, 19 groups of mixtures have been used to explore this topic. The results present that CaCO3 whisker can improve the compressive strength, peak strain and prepeak strain energy of steel-PVA HFRCC. Generally, HFRCCs reach better compressive behavior when the fibers size are grading. For example, 13mm steel fiber+ 6 mm PVA fiber+ whisker and 35mm steel fiber+ 12mm PVA fiber+ whisker are better than 13mm steel fiber+ 12mm PVA fiber+ whisker and 35mm steel fiber+ 6 mm PVA fiber+ whisker. The results are employed to develop formulas for calculating the strength, deformation, and toughness of HFRCC. Two models were developed to evaluate the stress-strain response of HFRCC. The prediction results of prepeak stress-strain curves using Model 2 (piecewise function involves a cubic parabola and a rational fraction) are closer to the experimental curves and lower than those using Model 1 (continuous rational power function). Therefore, Model 2 is recommended if more accurate prediction of the prepeak stress-strain curve is required. Otherwise, the simpler Model 1 can be used.