聚丙烯纤维掺量对再生混凝土抗折疲劳性能影响的试验研究

Experimental research on the effects of polypropylene fiber content on recycled concrete flexural fatigue performance

掺加聚丙烯纤维可提高再生混凝土抗折强度及抗折疲劳性能。制作了聚丙烯纤维掺量分别为0 kg/m^3、0.7 kg/m^3、1.0 kg/m^3、1.3 kg/m^3、1.6 kg/m^3的5种再生混凝土棱柱体试件,分别开展了抗折强度试验和在0.6、0.7、0.8 3种应力水平下的抗折疲劳试验,得到了其抗折强度和不同条件下的抗折疲劳寿命。试验结果表明,掺加聚丙烯纤维后,再生混凝土的抗折强度和抗折疲劳寿命可得到明显提升:聚丙烯纤维掺量为1.0 kg/m^3、1.6 kg/m^3时,抗折强度较不掺加聚丙烯纤维时可分别增长16.7%、23.9%,抗折疲劳寿命可分别增长至不掺加聚丙烯纤维时的1.9倍、2.5倍。根据疲劳试验数据,拟合得到了考虑聚丙烯纤维掺量的再生混凝土抗折疲劳S-N曲线方程,该方程适用于0~1.6 kg/m^3的常用聚丙烯纤维掺量范围内再生混凝土的抗折疲劳设计及计算分析。

By adding polypropylene fibers, the flexural strength and flexural fatigue properties of recycled concrete improved significantly. Five groups of different prism specimens of different polypropylene fiber contents were made to test flexural strength and flexural fatigue properties under three different stress levels. The five different contents were 0 kg/m3 , 0.7 kg/m3 , 1.0 kg,/m3 , 1.3 kg/m3 , 1.6 kg/m3 , and the three different stress levels were 0. 6,0. 7, 0. 8. The results showed that by adding polypropylene fibers, flexural strength and flexural fatigue life of recycled concrete improved significantly. When the content of polypropylene fiber was 1.0 kg/m3 ,flexural strength d recycled concrete increased by 16. 7% than that without polypropylene fiber, and the flexural fatigu~ life increased to 1.9 times of that without polypropylene fiber. While the content of polypropylene fiber was 1.6 kg/m3 ,flexural strength of recycled concrete increased by 23.9% than that without polypropylene fiber,and the flexural fatigue llfe increased to 2. 5 times o[＂ that without polypropylene fiber. The S-N curve equation of flexural fatigue life of recycled concrete when the content of polypropylene fibers were considered was fitted on the basis of the fatigue test data. This equation is applicable to the design, calculation and analysis of recycled concrete flexural fatigue life in the common range of polypropylene fiber from 0 to 1.6 kg/ms.