Fracture Performance of Early-Age Concrete Based on Acoustic Emission Measurement
In order to explore the fracture performance of early-age concrete,20 three-point bending beam fracture tests with precast cracks were carried out for concrete specimens of 5 different curing ages(3,7,14,21,28 d)to obtain their load-crack mouth opening displacement(P-CMOD)curves.Based on these curves,the fracture toughness(crack initiation toughness and unstable toughness)and fracture energy of early-age concrete were calculated.The effect of the curing age on the damage fracture process of early-age concrete specimens was investigated by using the acoustic emission(AE)technique through the curves of ringing counts and cumulative ringing counts versus time.The failure mode of early-age concrete was analyzed by calculating the rise angle(RA)and average frequency(AF).The results show that the fracture toughness and fracture energy of early-age concrete increase with the increases of curing age,the cracking resistance improves and the ductility deteriorates.The growth rate of concrete fracture toughness and fracture energy are faster from 3 d to 14 d,while the growth rate of concrete fracture toughness and fracture energy are slower from 14 d to 28 d.Both ringing counts and cumulative ringing counts can reflect the damage and failure process of concrete in early age.The growth rate of cumulative ringing counts decreases with the increases of curing age.The proportion of shear cracks to total cracks increases with the increases of curing age.
NETL
NSTL
万方数据
维普
