Research On Durability Of Concrete Structure In Service

The issue is from the National Science Foundation project "durability of concrete in service", grant No.:51068023.Today, the development of roads, bridges, water conservancy projects and other infrastructure construction is focused on in China, but the serious problem of the durability of concrete is exposed in a lot of existing construction projects. A large number of concrete structures are forced to be repaired or ahead of demolition and reconstruction before their expected service life, resulting in huge economic losses, waste of resources, environmental pollution and affecting sustainable development of society.The current study of the durability of concrete in guiding the design of construction is most at the "pure material" concrete stage. There is no full account of mechanical factors, environmental factors and material factors, resulting in the establishment of the theory does not meet the actual situation,causing durability problems highlighted at this stage.Based on the study of the durability of concrete, this paper gives full consideration to the load and environmental factors on the durability of concrete from the perspective of the concrete microstructure, studying the loading system how to simulate pore structure of concrete in service in the laboratory, finding out the relationship between the concrete pore structure and stress level in different strength concrete. Then, we can using the way of testing after loading to find out the relationship between pore structure, stress levels and chemical corrosion.The study finds:after using the loading system, the internal pore structure of concrete distribution in different stress levels of concrete is significantly different; Compared with the pure material, the chemical resistance of loaded specimens is significantly different.Tests show that the new research methods for the simulation of service loading of concrete pore structure distribution is valid, considering load factors, the chemical resistance of concrete in service research is closer to the actual situation. For the low, medium and high-strength concrete, although there are significant differences in water-cement ratio, but taking full account of loads, its chemical resistance is not much different; From the study we can see that the working stress range of different strength concrete should be best kept at about 40%, the working stress of high-strength concrete used in the corrosive environment should be best kept under 40%.