Study On Concrete Damage Evaluation Based On Acoustic Emission Detection Method

Acoustic emission(AE)method is a dynamic nondestructive testing technology developed in recent years,The localization and monitoring for damage of which are of great significance to the health monitoring and residual life prediction of concrete structures.In this paper,the optimization method of AE damage location and the characteristics of axial compression damage process for concrete were studied at meso-level.The AE pencil lead break test and elastic wave velocity test were carried out on concrete cube specimens.The arrangement of AE sensors and the selection method of AE experimental wave velocity were optimized based on the experimental results.A mathematical prediction model of AE experimental wave velocity for early-age concrete considering the influences of coarse aggregate volume rate,coarse aggregate maximum particle size and curing age was established.And the influences of coarse aggregate characteristics on the accuracy of AE damage location for concrete was evaluated.Simultaneously,the damage process of concrete has been analyzed by AE method combined with continuous axial load working condition(working condition I)and graded axial load working condition(working condition II),the velocity-stress relationship of concrete AE elastic wave considering the influences of coarseaggregate volume rate and maximum particle size was established.The optimization results in this study can reduce the error of traditional AE damage location to 20% at most,which has important guiding significance for identifying the potential location of future deterioration for structures.At the same time,the damage process of concrete was characterized by AE characteristic parameters and elastic wave velocity.The quantitative relationship between wave velocity and load holding stress level was established,which provides a theory for determining the service stress state of concrete structures or stress components in service,to make an effective warning at the early stages of degenerative process.