环绕黏结CFRP-ECC修复混凝土的动态力学和能量特性

Dynamic Mechanical and Energy Characteristics of CFRP-ECC Repaired Concrete with Surrounding Bonding Method

为了研究环绕黏结碳纤维增强复合材料(CFRP)与工程水泥基复合材料(ECC)构成的复合增强层对小尺寸受损混凝土的修复效果,制备CFRP增强ECC-混凝土组合体试件,采用霍普金森压杆对端面粘贴、环绕粘贴CFRP的组合体进行不同气压下的冲击压缩试验。结果表明:两种组合体的峰值应力、峰值应变和动态增长因子均随冲击气压的升高而增大,环绕粘贴CFRP的组合体峰值应力、峰值应变均高于端面粘贴CFRP的组合体,0.5 MPa气压作用下,峰值应力增长达10.9%,峰值应变增长达14.98%。随着气压的升高,两种组合体的动态增长因子均呈增大趋势,两种组合体在0.7 MPa较0.3 MPa作用下,DIF分别提高了56.77%,59.41%,具有明显的应变率增长效应。0.7 MPa气压时,两种组合体的DIF均在1.6左右,因此两者均适用于高动态荷载作用环境。复合增强层为混凝土提供良好的环向约束力,有效抑制裂纹扩展。环绕粘贴CFRP的组合体破坏状态优于端面粘贴CFRP的组合体,抗冲击性能更好。两种组合体的各能量变化趋势相似,均随着气压升高而增大,且环绕粘贴CFRP的组合体较端面粘贴CFRP的组合体能量吸收能力更强,0.7 MPa时的吸收能增幅在5%左右。在小尺寸混凝土修复工程中,环绕粘贴CFRP与ECC构成的复合增强层的修复效果更佳。

To investigate the remediation effect of composite reinforced layer composed of surrounding bonded carbon fiber reinforced polymer(CFRP)and engineered cementitious composite(ECC)on small-size damaged concrete,the CFRP reinforced ECC-concrete combination specimens were prepared.The impact compression tests under various air pressures were carried out on the combination specimens of end-face bonded and surrounding bonded CFRP by using Hopkinson pressure bar.The result indicates that the peak stress,peak strain and dynamic increase factors of both combinations increase with the increase of impact pressure.The peak stress and peak strain of the combination of surrounding bonded CFRP are higher than those of the combination of end-face bonded CFRP.At 0.5 MPa pressure,the peak stress increases by 10.9%,and the peak strain increases by 14.98%.As the air pressure increases,the dynamic increase factors(DIFs)of both combinations show the increasing trend.Compared with the effect under 0.3 MPa,the DIFs of the two combinations under 0.7 MPa increase by 56.77%and 59.41%respectively,indicating the significant strain rate increase effect.At 0.7 MPa air pressure,the dynamic increase factors of both combinations are around 1.6,which are both suitable for high dynamic load environment.The composite reinforced layer provides the good circumferential restraint force for concrete,and effectively inhibits the crack propagation.The failure state of surrounding bonded CFRP combination is superior to those of end-face bonded CFRP,demonstrating better impact resistance.The energy trend of both combinations follow the similar pattern,increasing with the air pressure.Moreover,the surrounding bonded CFRP combination exhibits stronger energy absorption capacity compared with those of end-face bonded CFRP with an approximate 5%increase in absorbed energy at 0.7 MPa.In small-scale concrete repair projects,the repair effect is more significant when using the composite reinforced layer composed of surrounding bonded CFRP-ECC.