Study on the Investigation of the Fatigue Behavior of Engineered Cementitious Composites with High Tenacity Polypropylene (HTPP) Fibers

Abstract

In this study, the fatigue behavior of Engineered Cementitious Composites incorporating high tenacity polypropylene fiber was investigated. The strain curves, cycle numbers, crack numbers and stiffness values were obtained from the experiments carried out with the load-controlled fatigue method at 80, 90 and 110% stress level (maximum stress/ultimate static strength). In conclusion, at 80% stress level, average 1127 cycles, 1.37% the unit deformation capacity and 6 cracks were achieved. At 90% stress level, 215 cycles, 1.89% the unit deformation capacity and 8 cracks were obtained. In the specimens where 110% stress level was applied, the average number of cycles was decreased to 38 cycles, the unit deformation capacity increased up to 2.60% and the average number of cracks also doubled and raised to 15 cracks. Additionally, the average stiffness values of 8.68 and 9.57 GPa were obtained in the first cycles at 80% and 90% stress levels, it was observed that the stiffness values gradually decreased with increasing cycles. Although high strain values were achieved at the 110% stress level, micro cracks were formed suddenly due to the very high applied loading and the rigidity values remained low since the first cycle due to the plastic deformation.