桥梁用聚丙烯纤维增强水泥基复合材料的力学性能

Mechanical properties of polypropylene fiber reinforced engineering cementitious composites for bridges

为了给所提出的一种新型桥梁用聚丙烯纤维增强水泥基复合材料(PP-ECC)的工程应用提供技术支撑,开展了PP-ECC的力学性能研究。首先,考虑粉煤灰掺量对PP-ECC性能的影响,设计了3种配合比方案,测试了3种配合比方案的抗压强度、抗折强度、抗压回弹模量等基本力学性能。接着,从3种配合比中优选出一种配合比方案,通过四点弯曲试验对其弯曲特性进行了全过程表征,并定量评价了其弯曲韧性。结果表明,本文制备的PP-ECC的60 d抗压强度为50~54 MPa,抗折强度达到了7~8 MPa,抗压回弹模量仅为8~10 GPa。本文制备的PP-ECC在四点弯曲试验中表现出了多缝开裂现象和变形硬化行为,试件的弯曲韧性指标达到了37.10,且残余强度指标值几乎都大于1.0,说明这种新型材料具备一定的强度、良好的裂缝控制能力和变形能力,可作为桥梁关键部位建筑材料。

In order to provide technical support for the engineering application of a new polypropylene fiber reinforced cement-based composite(PP-ECC) for bridge,the mechanical properties of PP-ECC were studied. First,considering the effect of fly ash content on the properties of PP-ECC,three matching ratio schemes were designed to test the basic mechanical properties such as the compressive strength,flexural strength and the compressive resilience modulus. Then,a kind of matching ratio scheme was selected from the three matching ratios,and the bending properties were characterized by the four-point bending test for the whole process,and the bending toughness of the PP-ECC was quantitatively evaluated. The results show that the compressive strength of the PP-ECC prepared in this paper is 50-54 MPa,the flexural strength is 7-8 MPa,and the compressive resilience modulus is only 8-10 GPa. In the four-point bending test,the PP-ECC prepared in this paper shows a multi-joint cracking phenomenon and a deformation hardening behavior. The flexural toughness index of the test piece reaches 37.10,and the residual strength index value is almost all greater than 1.0,which indicates that the new material has certain strength,favorable crack control ability and deformation capability. The testing results suggest that the PP-ECC can be used as a building material for key parts of the bridge.