Study On The Application Of Smart Concrete In Monitoring Corrosion And Protecting Of Reinforced Bars

The brief research in this dissertation is twofold: one is the monitoring of the corrosion of reinforced bar in concrete by using the compression sensibility of smart concrete; the other is the prevention of the corrosion of reinforced bar by using the smart concrete pn junctions. Due to the two subjects, the following researches are carried out.1. The monitoring of the corrosion of reinforced bar by using the compression sensibility of smart concrete: 1) A new model of corrosion expansion of reinforced bar are upbuilt to calculate the corrosion expansibility based on the analysis of research situation of reinforced bar corrosion. In this model the anisotropic constitutive models of concrete are introduced according to its different behaviors under compressive stress and tensile stress, and it is considered that a certain amount of rust product is carried away from the rust layer around the reinforcement and deposited within the open cracks after the cover cracked, which will reduce the expansive pressures. 2) The mechanisms of compression sensibility of smart concrete are studied, and the methods of applying its compression sensibility to monitor reinforcement corrosion are explored. It shows that it can effectively monitor the state of the reinforced barby bundling uniformly smart concrete around the reinforced bar.2. The prevention of the corrosion of reinforced bar by using the smart concrete pn junctions. 1) The conductivity of SFRC is tested in experiments. The test studies show that SFRC has better electric conductivity than plain concrete, while the resistance is still remarkable because of the corrosion of steel fiber. At the beginning of the curing period, the resistance of SFRC increases rapidly, and then tends to stable. And the resistance will decrease with the increasing of the volume fraction of steel fiber. 2) The cement-based pn-junctions are tested in experiments. Experiments show that the cement-based pn-junctions have a good unilateral conductivity. The inverse saturation current decline as time goesby and depend on the volume fraction of fiber. 3) The applications of smart concrete on the prevention of reinforcement corrosion are primarily explored. (1) CFRC can effectively reduce the driving voltage required by catholic protection because of its good electric conductivity; (2) Applying cement-based pn-junctions on the prevention of reinforcement corrosion. In the interface of p-type region and n-type region of pn junctions a self-built electric field will be formed, and its direction is from n-type region to p-type region. If the reinforced bars are bundled uniformly by the cement-based pn-junction and the SFRC is close to the reinforced bars, which can enhance the electron work function without any loss of the performance of structure, the cement-based pn-junctions will prevent the reinforced bars from corroding.