Abstract
In order to solve the technical problem of damage localization in the concrete damage process, the Computerized Tomography (CT) scanning test and Acoustic Emission (AE) damage localization test was carried out under uniaxial compression. In addition to the three-dimensional meso model, the porosity variation law of concrete pore or cracks at different loading stages are obtained. A damage variable is created based on CT images and AE damage points. A damage variable based on CT image and AE damage point is established. The results show that the change of porosity, pore volume and damage variable is consistent with the loading process. The rapid increase of concrete pore volume and damage variable can be the precursor of concrete damage. The whole process of the development and evolution of concrete cracks was observed and analyzed comprehensively by using the three-dimensional reconstruction images and acoustic emission damage location map. A new method for analyzing the evolution and localization of cracks in concrete is presented.
Highlights
Concrete is a kind of complex multi-phase composite material, initial defects such as micro cracks and pores generate in concrete structure in the process of pouring for the reason of hydration heat release, shrink, etc
The current research of concrete is based on the conventional mechanics test method, that is speculate the mechanical character of structural materials through comparative analysis of test data instead of using the change of the internal meso structure directly to explain the damage evolution process under the load [2]
CT is short as Computerized Tomography, compared with other methods, CT test has its incomparable advantage on nondestructive detection and real time observation in concrete material under various loading condition
Summary
Concrete is a kind of complex multi-phase composite material, initial defects such as micro cracks and pores generate in concrete structure in the process of pouring for the reason of hydration heat release, shrink, etc. A large number of concrete CT tests were carried out in China, and abundant research results were obtained: academician Chen Houqun using CT real time scanning to observe the meso failure process of concrete under the uniaxial compression, the whole process CT images of internal meso cracks from initiation, expansion to coalescence was got, quantitative analysis methods based on concrete CT images was established in the cracks area. As the unique passive detection technology in nondestructive testing, acoustic emission detection technology can monitor and evaluate the whole concrete structure in real-time, acoustic emission signal can reflect the change situation of the internal structural damage accurately except for its defects that can’t be observed evolution of pore and damage in structures directly. The meso structure of concrete and its changing process was analyzed with the feature of CT images, the order of damage evolution in concrete is described by damage variable based on CT images
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