Impact of Low Calcium Fly Ash on Steel Corrosion Rate and Concrete– Steel Interface

The use of fly ash is not only in harmony with the concept of sustainable development, but also beneficial to some mechanical properties of concrete. This paper discusses steel corrosion rate time-changing law in concrete with different replacing ratios of low calcium fly ash(10%~30%) and the microcosmic characteristic of concrete-steel interface. The steel corrosion rate was tested by linear polarization and weak polarization for corrosion monitoring in man-made climate environment, the microcosmic characteristic of concrete-steel interface was observed by Electronic Microscope and Scanning Electron Microscope. The experimental results showed that addition of 10%~30% fly ash increased the ability of concrete to resist steel corrosion, and the concrete with 20% replacement ratio of fly ash had the least corrosion layer thickness. The microscopic and microcosmic results further verified and explained the point of view. The analytical results of present work showed that the addition of fly ash in concrete had dual effects: (a) reducing concrete porosity and (b) improving the concrete-steel interface structure. Therefore, the replacement ratios of 10%~30% low calcium fly ash can be effectively used in structural concrete.