Self-sensing Of Freeze-thaw Damage And Bending Damage Of Multiphase Electrically Conductive Concrete

Cumulative damage and the degradation of structure or material resistance are the common reasons for the failure of conventional concrete structures like bridges, power station, coastal and offshore engineering and other structures under different load, fatigue or erosion effect or material aging. The security and disaster prevention capabilities of engineering structures have been increasingly favored by people. The features of health monitoring of structures which can assess the internal damage of concrete structures in real time, and consequently can take actions to avoid the emergent fatal accident. As one of the important branchs of smart materials, electrical conduction concrete can sense the strain, damage and temperature due to the sensitivity, which can be used to monitor the strain and stress state of dams, roads, bridges, bridges, power station, coastal and offshore engineering without the need of embedded, attached or remote sensors.On the basis of present situation of domestic and foreign studies, the nano carbon black, carbon fiber and steel fiber have been added to the plain concrete to produce the multiphase electrical conductive concrete. After that, the workability, mechanical properties, conductivity of electrical conductive concrete with diferent kinds and dosages of conductive materials have been investigated. Then the self-sensing of freeze-thaw damage and bending damage of multiphase electrical conductive concrete have been studied. The prime tasks are as follows:(1) The effects of nano carbon black, carbon fiber and steel fiber added to the concrete on the workability have been investigated and compared.(2) The effects of nano carbon black, carbon fiber and steel fiber added to the concrete on the compressive strength have been compared and investigated.(3) The effects of nano carbon black, carbon fiber and steel fiber added to the concrete on the impedance of dry and soaked concrete have been compared and investigated.(4) The relationships of the number of freeze-thaw cycles and the fractional change in impedance of conductive concrete beams with diferent kinds and dosages of conductive materials have been studied. Based on this, the application of these relationships on the the self-sensing of freeze-thaw damage, the estimation and prediction of service life of concrete members in freeze-thaw condition have been investigated.(5) Based on the relationship between the strain of geometrical neutral axis and the fractional change in resistance of electric conductive concrete beams subjected to flexural load which have been found in the previous investigations, and combine the damage mechanics theory, internal damage of the concrete was indicated by the relationship between the degree of damage and resistance. This self-sensing of damage in conductive concrete can be applied in monitoring damage to flexible components as a new way.