음향방출 기법을 이용한 섬유보강 시멘트 복합체의 정량적 손상평가

Abstract

Dept. of Civil System Engineering, Konyang University, Chungnam 320-711, KoreaABSTRACT Fiber is an important ingredient in fiber-reinforced cement composite (FRCC) which can control fracture of cementcomposite by bridging action. In compliance with the action of the fiber and the aggregate size, it also showed a different failure mech-anism. For practical application, it is needed to investigate the fracture behavior of the FRCC and to understand the micro-mechanismof cement matrix with reinforcing fiber. In order to evaluate a characteristics of fracture process in the FRCC, acoustic emission (AE)technique was used for the analysis and evaluation of FRCC damage by acoustic emission under flexural and cyclic compressive load-ings. The AE signals were monitored by AMSY4 AE instrument during the entire loading period. The specimens are reinforced with0, 1.0, 1.5 and 2.0% (by volume) Polyvinyl alcohol (PVA) fiber. The test results showed that the damage progress of the FRCC wascharacteristic for the fiber replacement ratio. As a result of analyzing the felicity ratio (FR) values, it is shown that this values can beused for evaluating the degree of FRCC damage. On the whole the felicity ratio values of FRCC are shown between 0.4 and 1.1. And,the AE kaiser effect was shown in the all FRCC specimen. In addition, the damage behavior and the microscopic fracture process ofthe FRCC are evaluated using the AE parameters, such as calm ratio, b-value and felicity ratio. The purpose of this reserch was toadvance the state of knowledge regarding the applicability of acoustic emission as an evaluation method for FRCC.Keywords : fiber-reinforced cement composite, bridging action, Kaiser effect, calm ratio, b-value