【作者】 韩建宏；

【导师】 娄宗科；

【作者基本信息】 西北农林科技大学 ， 水利水电工程， 2010， 硕士

【摘要】 层布式混杂纤维混凝土(LHFRC)是将高弹性模量的纤维均匀分布于混凝土上下表面一定厚度的表层内,而将聚丙烯等有机纤维三维乱向分布于整个混凝土构件内部的一种新型混凝土。这种新型混凝土一方面发挥了两种纤维的混杂效应,另一方面则在结构上充分利用了路面混凝土的受力特点,正是由于这种形式和结构上的双重优势,进一步改善了纤维混凝土的力学性能和耐久性能,已经被越来越广泛地应用于公路路面设计。目前的研究主要集中在钢纤维-有机纤维混杂的混凝土上,而关于碳纤维-聚丙烯纤维混杂的新型层布式混凝土的研究报道尚未见到。本文便以层布式碳纤维-聚丙烯混杂纤维混凝土为研究对象,首先对其力学性能做了简要分析,在此基础上对其冻融损伤过程进行了探讨,以便为今后在工程中的应用提供参考。本文主要开展了以下几个方面的工作:(1)采用四因子二次回归通用旋转组合设计,研究了水胶比、粉煤灰掺量、聚丙烯纤维掺量和碳纤维掺量对LHFRC力学性能的影响。结果表明,二次多项式回归模型可用于表征层布式混杂纤维混凝土28d抗压强度和抗折强度,当水胶比为0.3,粉煤灰掺量、聚丙烯纤维掺量和碳纤维掺量均为0时,混凝土28d抗压强度最大值可达到68.21MPa;当水胶比为0.3,粉煤灰掺量为0,聚丙烯纤维掺量为1.2%,碳纤维掺量为1.6%时,混凝土抗折强度可达到最大值8.84MPa。该结果进一步表明了聚丙烯纤维和层布式的碳纤维对混凝土抗压强度影响不大,对抗折强度影响显著;(2)采用快速冻融法,研究了素混凝土、层布式碳纤维混凝土、整体式聚丙烯纤维混凝土和层布式碳纤维-聚丙烯混杂纤维混凝土经受100次冻融循环作用后的相对动弹性模量、质量、冻后力学性能以及表观性状的变化情况。研究表明,层布式碳纤维-聚丙烯混杂纤维混凝土抗冻能力最强,并且冻后抗折强度损失最少;(3)研究了素混凝土、层布式碳纤维混凝土、整体式聚丙烯纤维混凝土和层布式碳纤维-聚丙烯混杂纤维混凝土的损伤演变规律,确定了具体参数,得出其损伤演变方程。试验结果表明,本文所选择的混凝土损伤演变模型可以较好的表征该条件下上述四种混凝土的冻融损伤演变过程。更多还原

【Abstract】 The layer hybrid fiber reinforced concrete is a new concrete that the fiber of high elastic modulus is bestrewed in the upper and lower surface of a certain thickness, and the polypropylene fiber is distributed in the whole concrete members uniformly. This concrete occurs hybrid effect through doping two types of fiber in form on the one hand , and utilizes the stress characteristics of the pavement concrete in structure on the other hand. The study about the new concrete that intermixes the carbon fiber and the polypropylene fiber is not multiple. This paper analyzes the mechanical properties briefly according to LHFRC, and discusses its freezing-thawing damage primarily on this basis, so as to provide reference for the application of pavement engineering in the future. Main works as following:The first, it studies the effects of the main factors, such as water-binder ratio, the content of fly ash, the content of the polypropylene fiber and the content of the carbon fiber on the 28d mechanical properties of the layer hybrid carbon fiber-polypropylene fiber reinforced concrete by using the second-degree current spinning combination design of four factors. The result shows that, quadratic polynomial regression model can be used to establish the regression equation of the 28d compressive strength and flexural strength of the layer carbon fiber and polypropylene fiber. When the water-binder ratio is 0.3, the content of fly ash、the content of the polypropylene fiber and the carbon fiber are all 0, the 28d compressive strength of the layer carbon fiber and polypropylene fiber can reach the maximum 68.21 MPa; While the four factors respectively are 0.3、0%、1.2% and 1.6%,the maximum 28d flexural strength is 8.84 MPa. The effect of polypropylene fiber and the layer carbon fiber on the concrete compressive strength is little, but significant on the concrete flexural strength;The second, with the rapid frozen thaw method, this paper comparative studies the frost resistance of the ordinary concrete(OC)、layer carbon fiber reinforced concrete (LCFRC)、polypropylene fiber reinforced concrete(PFRC) and layer hybrid fiber reinforced concrete(LHFRC) after 100 times freeze-thaw cycles. The study shows that, the frost resistance of the LHFRC is the best, and its loss of flexural strength post freezing is least;The third, this paper studies the damage evolutional law of the above four types of concrete, determines the concrete parameters, regresses the damage evolutional equation. The results show that the model of damage evolution is suitable for that four types of concrete of our test conditions, and it can characterize their freezing-thawing damage evolution process better.更多还原