有机纤维对“客运专线”用C40高性能混凝土性能的影响

Effects of Organic Fiber on Properties of C40 High Performance Concrete for Passenger Dedicated Line

目的为增强混凝土早期抗塑性开裂性能及耐久性,研究了有机纤维种类、长度及掺量对混凝土工作性能、力学性能及抗碳化性能的影响.方法采用坍落度试验、抗压与抗折强度试验、混凝土碳化试验及平板约束法测试进行研究.结果聚丙烯腈(PAN)纤维对混凝土工作性能影响最大,坍落度降幅达86%;掺入19 mm聚丙烯(PP)单丝纤维,坍落度下降25%;加入0.15%PP纤维,坍落度降幅达28.7%,含气量增加25.9%;掺入聚乙烯醇(PVA)纤维后,混凝土7 d、28 d抗压强度降幅最大,分别达30.4%、23.5%;12 mm PP单丝纤维体积掺量为0.15%时混凝土的抗裂效果明显好于0.05%掺量,而碳化深度较基准低30%.结论混凝土中掺入有机纤维后,早期抗塑性开裂性能明显增强;混凝土的抗裂效果随纤维长度和掺量增加,效果越来越明显;有机纤维的加入明显提高混凝土的抗碳化力,力学性能有所降低,但降幅不大.

To enhance the early concrete plastic cracking resistance and durability, this paper studied the effect of the types, length and content of organic fbers on concrete working performance, mechanical properties and carbonization resistance, through the slump test, compressive strength and flexural strength test, concrete carbonation test and flat restraint method. The results show that PAN fiber has the greatest impact on the performance of concrete, slump has a drop of 86% ; after adding 19 mm PP monofilament fibers, slump decreases by 25% ;when adding 0. 15% PP fibers,concrete slump has a drop of 28.7% ,air content has an increase of 25.9 % ; after the incorporation of PVA, compressive strength for 7 d, 28 d of concrete give the largest declines,respectively,which are 30. 4% ,23.5% ; while 12 mm PP monofilament fiber volume fraction reached 0. 15%, the effect of concrete cracking is obviously better than 0. 05% of the dosage, but the carbonization depth is lower than the benchmark by 30%. The conclusion indicates that after adding organic synthetic fibers to concrete, the resistance to plastic cracking of concrete at early age significantly is en- hanced. The effect of the resistance to cracking of concrete is getting better and better along with the increase of fiber＇ s length and content. The carbonation resistance of concrete is obviously improved after adding the organic fibers, but the mechanical properties reduce a little bit.