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