基于声发射技术的高韧性水泥基复合材料开裂损伤特性

研究了同等抗压强度等级的普通混凝土和高韧性水泥基复合材料的抗弯拉力学性能,采用声发射(AE)技术对比检测和分析了二者在三分点弯曲荷载作用下的开裂损伤规律。力学测试结果表明,高韧性水泥基复合材料具有较高的抗弯拉强度和应变硬化能力。AE检测结果表明,随着普通混凝土强度的增大,AE信号幅度增大,但其AE事件总数增长规律和幅值分布规律与强度无明显关系;高韧性水泥基复合材料AE信号的幅值和分布密度均比同等抗压强度等级的普通混凝土小;普通混凝土试件的断裂过程区主要集中在断裂面附近,而高韧性水泥基复合材料基本已覆盖了整个纯弯段,在细密裂缝的扩展过程中高强纤维对裂尖能量进行了有效的吸收和传递。

Study on the Fracture Damage Characteristic of High Toughness Cementitious Composite with Acoustic Emission Technique

This paper presented the research on the bending performance of ordinary concrete and high toughness cementitious composite at the same level of compressive strength,and the fracture process of these two materials under third-point bending test with acoustic emission(AE) technology.Mechanical test results show that high toughness cementitious composite possesses higher bending strength and strain hardening ability.AE test results indicate that AE signal amplitude increases with the rise of common concrete strength while there is no significant relationship between the increase of strength and cumulative number of AE events and amplitude distribution rule.The amplitude and density of the acquired signals for high toughness cementitious composite is lower than ordinary concrete at the same level of compressive strength.The breaking process area of ordinary concrete mainly concentrates near the fracture surface.On contrast,it almost covers the whole pure bending section for high toughness cementitious composite.During the expansion of the multiple cracks,the crack tip energy has been effectively absorbed and transferred by the high-strengh fibers.