Research And Life Prediction On The Durability Of Marine Engineering Concrete Structure

Marine Engineering concrete structures are used in harsh environments. They has long been the erosion of chloride ions in sea water, and are carbonized by the carbon dioxide in the air, Resulting in reinforced concrete structures is easily corroded. Concrete structures faced with severe challenges. Improving the resistance to chloride ions, carbon dioxide corrosion performance of marine engineering concrete has become an inevitable way to improve the life of concrete structures, and reducing the economic cost.Concrete resistivity are tested by means of the RESIR resistivity Tester. Electric flux and chloride ion diffusion properties of concrete are tested. We use resistivity of concrete, chloride ion diffusion coefficient of concrete carbonation depth as characterization. And we studied materials(including water-cement ratio, mineral species, mineral content, etc.) affecting the durability of concrete resistance to chloride ion penetration and anti-carbonation, etc. And at last we put forward concrete life prediction model basing on chloride ion penetration, providing theoretical guidance for practical engineering applications.1、Firstly,this paper studied the effects of material composition for the concrete resistivity of marine engineering concrete. The results show that: The concrete resistivity in the environment 2(RH = 65%) is bigger than the one in the environment in(saturated water).The concrete resistivity is closely related to its internal porosity and pore connectivity degree. The lower the Porosity and pore connectivity degree, the resistivity is large. The amount of cement, water-cement ratio and mineral admixtures influence of resistivity is mainly because of their impact on the concrete porosity and pore connectivity degree. Incorporation of mineral admixtures can significantly increase the resistivity of concrete. And these three mineral admixtures for affecting the concrete resistivity are: silica fume> slag> fly.2、Secondly,this paper studied marine engineering concrete material impact on the composition of chloride ion diffusion performance. The results show that: curing period for resistance to chloride ion corrosion properties has a major impact. The 90 days age of concrete’s electric flux is smaller than 28 days age, the larger water-cement ratio, the greater the electric flux, and inside chloride ion concentration the higher. We should reduce water of marine engineering concrete under the premise of ensuring that other performance. Incorporation of fly ash can improve the flow properties of fresh concrete, reduce coarse pores, but also can improve the resistance to chloride corrosion performance. And the suitable dosage is about 35%. Silica fume can fill the pores and reduces pores finer porosity of the concrete, better resistance to chloride ion penetration performance. But the cost of silica fume is too high, so the suitable dosage is about 3%. Silica fume, fly ash can make full use of the advantages of both, so that the resistance to chloride ion corrosion performance improved greatly.Finally, according to the data, we propose a concrete structure durability life prediction. We pointed out the Fick’s second law can be a simple and effective model to predict the durability of concrete resistance to chloride ion penetration life. We proposed a reasonable choice of concrete cover thickness on the extension of durable life of concrete structures, to reduce the cost of construction is important.