Experimental studies of diphasic electric conduction concrete applying in the diagnosis of the damnification

In order to study the relationship between concrete damage and the electric resistance change of electric conductive concrete, concrete beams containing nano-meter carbon black or carbon fiber subjected to loading were investigated. The relationship between the resistance change rate of concrete beams and the strain of geometrical neutral axis was established using an analogy method and a experimental data regression. Based on the damaging mechanics theory and the relationship above, the expression between degree of damnification and the rate of resistance change was set up. This self-diagnosis of conductive concrete material provides a new way for the measurement of the internal damage. The results show that the relationship between the rate of resistance change of concrete beams and the strain of the geometrical neutral axis can be well fitted by the exponential decay first order curve before cracking. The sensitivity of the electric conduction concretes can be reflected directly by the slope of the fitted curve, and the degree of concrete damage can be also indirectly responded.