Study Of Chloride Ion Permeability And Steel Corrosion In Low-Quality Fly Ash Concrete

Along with the quick development of the electric power industry, the amount of generation of fly ash has increased year by year, and the utilization of fly ash has not kept up with the growth of fly ash generation, causing the fly ash piled up in large quantities, take up the land, and pollute the environment seriously. Whether in the test research, or the product development of higher quality fly ash, the substantial progress has been made. But the researches and exploitations of low-quality fly ash are still at an early stage. Therefore, it is necessary to pay attention to the research of the â…¢ class fly ash, and improve the utilization of low-quality fly ash.There are plenty of problems needed to be broken in the application of low-quality fly ash in civil engineering. In generally, most of the researches mainly study the basic mechanical properties of low-quality fly ash concrete, but pay little attention to the Chloride ion permeability and steel bar corrosion in concrete containing low-quality fly ash. The researches on Chloride ion permeability and steel corrosion in low-quality fly ash concrete are carried on in this text.The main achievement of this thesis includes the following aspects:(1)The experiment results of the mechanical properties of low-quality fly ash concrete show: at early curing ages (7 days for example), the compressive strength of fly ash concrete, which is lower than the strength of the normal concrete, decreases along with the increase of the content of fly ash. The 90 days strength of fly ash concrete has already caught up with or exceeded the strength of normal concrete. According to the test, the strength of â…¢ class fly ash concrete is not evidently lower than the â… class fly ash concrete.(2) Rapid chloride permeability experiment is adopted to test the anti-chloride ion permeability of the low-quality fly ash concrete. The result shows that the electric shock of the chloride permeability of fly ash concrete decreases greatly. It shows that adding the fly ash to concrete can raise the ability of anti-chloride ion permeability of concrete, and the best content of the fly ash is related to the grades of the concrete. In this thesis, in C30 class and C40 class concrete, when the amount of fly ash attains 30 percent, the concrete has the best anti-chloride ion permeability, and in C50 class concrete, when the amount of fly ash attains 40 percent, whether adding â… class fly ash or adding â…¢ class fly ash, the electric shock going through the concrete within 6 hours is in the lowest level, and the concrete has the best ability of anti-chloride ion permeability. According to the experiment result, the anti-chloride ion permeability of the â…¢ class fly ash concrete is not lower than the â… class fly ash concrete.(3)The influence of the quality and the content of fly ash on steel bar corrosion is similar to that on anti-chlorine ion permeability. It shows that adding the low-quality fly ash can improve the ability of anti-eclipse of reinforce bar. Under the same mixture ratio, the protection of the â…¢ class fly ash concrete of reinforce bar is not lower than that of theâ… class fly ash concrete.