|主題||EVALUATION OF DETERIORATION IN CONCRETE BY ACOUSTIC EMISSION ACTIVITY
The evaluation of deterioration in concrete is recently of significant importance, because a large number of concrete structures are going to approach to their service-life limit and require proper repairing for the rehabilitation. For a diagnostic inspection, we have proposed an application of acoustic emission (AE) observation to tests of core-drilled samples from concrete members. AE activity during uniaxial compressive loading is analyzed in a core sample, based on the rate process theory. To gauge of this technique and to quantify a parameter of rate, core samples are selected from reinforced concrete（RC）slab specimens, which have been tested under cyclic loading. Thus, the evaluation of the deterioration in concrete by AE activity is performed, by using core samples of controlled damage.
To assess the deterioration of concrete structures, a method to monitor the AE activity core specimens under uniaxial compressive loading was invesigated. Core samples were extracted from three RC slabs. One of three RC slabs was loaded monotonously up to final failure, and the other were tested by cyclic loading. Thus, controlled damaged concrete members were obtained. Since AE activity becomes high when concrete concrete contains many critical microcracks, the tendency was quantitatively evaluated on the basis of the rate process theory. Although extensive systematic study is still required to link the value of “a” to the deterioration degree of concrete, some quantitative relations between the values of “a” and the crack densities (C.D) of the RC slabs were found. It shows a great promise for the quantitative of deterioration in concrete by AE observation of core tests.