In this paper, comparative experimental study on the performance of steel fiber and PET fiber reinforced concrete has been performed. Experimental tests were carried out to highlight the effect of PET fiber parameters, mainly fiber dimensions, on the mechanical properties and fiber pull-out behavior of concrete. Results indicate that compared with steel fiber the performance of PET fiber is not good to enhance the mentioned properties, especially for compressive strength and modulus of rupture. Results showed that, in contrast to steel fiber, the performance of concrete with short and thick PET fiber is better. The existence of PET fiber in concrete has an influence on the crack bridging and changing the mode of failure of concrete to be less brittle. On the failed concrete surface, pull-out of PET fiber was not observed for concrete subjected to tension and flexure, and specimens were failed after large elongation of the plastic fiber. Analysis of global data was made to develop equations for calculating compressive strength, splitting tensile strength and modulus of rupture. Results of regression analysis indicate that these properties of concrete are dependent on the fiber index (V_f l_f/d_f). Useful limits of fiber index were determined for each property helpful for the accurate using of PET fiber in concrete and avoiding high strength losses.

本文对钢纤维和PET纤维增强混凝土的性能进行了对比试验研究。进行了实验测试以突出 PET 纤维参数（主要是纤维尺寸）对混凝土力学性能和纤维拔出行为的影响。结果表明，与钢纤维相比，PET纤维的性能并不能很好地提高上述性能，尤其是抗压强度和断裂模量。结果表明，与钢纤维相比，PET纤维短而粗的混凝土性能更好。混凝土中 PET 纤维的存在对裂缝桥接和改变混凝土的破坏模式有影响，使其脆性降低。在破坏的混凝土表面上，对于受拉和弯曲的混凝土，未观察到 PET 纤维的拉出，并且在塑料纤维的大伸长率后，试样失败。对全球数据进行分析以开发计算抗压强度、劈裂抗拉强度和断裂模量的方程。回归分析结果表明混凝土的这些性能取决于纤维指数（V _f l _f / d _f )。确定了有助于在混凝土中准确使用 PET 纤维并避免高强度损失的每种特性的有用纤维指数限值。