采用聚乙烯纤维( PE) 和聚丙烯塑钢纤维( HPP) 混杂技术制备纤维混凝土，以冻融前后的质量变化、动弹性模量、抗压强度以及弯曲性能等对其抗冻性能进行评价，并结
合SEM 分析从微结构角度对其损伤机理进行探讨． 研究表明: 冻融循环后素混凝土表面受损明显，混杂纤维掺入可以提高混凝土的完整性，表面损伤剥落减少; 冻融循环过程中素混凝土的质量呈先增长后降低的趋势，而混杂纤维混凝土的质量呈持续增长状态; 各配比混凝土的动弹性模量先基本不变而后下降，当纤维掺量为0． 8% + 1． 2%时经受300 次冻融循环作用后的相对动弹性模量仍保持在83． 63%; 各组混凝土抗压强度变化规律与动弹性模量相似; PE 和HPP 粗细纤维的协同作用使混凝土脆性显著改善，混杂纤维混凝土的韧性指数与残余强度随纤维掺量而变化，当掺量为0． 8% + 1． 2% 时优于理想弹塑性材料; 经冻融作用后，混凝土的弯曲韧性有一定的损伤，但没有出现脆性断裂，仍表现出较好的延展性．

In this paper,first,hybrid fiber-reinforced concrete was prepared by using the hybrid fiber of polyethylene fiber ( PE) and polypropylene plastic fiber ( HPP) .Then,the frost resistance of the reinforced concrete before and after the freeze-thaw process was investigated in terms of quality variation,dynamic elasticity modulus,compressive strength and flexural performance.Finally,the damage mechanism of the concrete was analyzed by using SEM analysis technique.The results show that ( 1) freeze-thaw cycles may cause obvious damage to plain concrete,and hybrid fiber can improve the integrity of concrete and decrease the surface damage; ( 2) the quality of plain concrete first increases and then decreases in the freeze-thaw cycle,while that of the hybrid fiber-reinforced concrete continuously increases; ( 3) the dynamic elastic modulus of the concrete with different proportions almost remains unchanged at first and then decreases; ( 4) after 300 freeze-thaw cycles,the relative dynamic elastic modulus of the concrete with a fiber content of 0. 8% + 1. 2% still keeps at 83. 63%; ( 5) the variation rule of compressive strength is similar to that of the dynamic elastic modulus; ( 6) the synergistic effect of fine-PE and coarse HPP fibers significantly improves the brittleness of concrete; ( 7) both the toughness index and the residual strength of hybrid fiber-reinforced concrete vary with the fiber content; ( 8) the prepared reinforced concrete is superior to the ideal elastic-plastic material when the hybrid fiber content is 0. 8% + 1. 2%; and ( 9) freeze-thaw cycles may result in certain damage to the flexural toughness,but still no brittle fracture appears,and the concrete still possesses good ductility.