A Study Of The Improving Technical Of The Durability Of Concrete Application In High Speed Railway In Frozen Earth Area

With the improvement and perfection of high-speed rail lines(HSR) in China, it is difficult to avoid frozen earth areas that build more and more high-speed rail lines. The serious requirements of quality of high-speed rail construction increased strict due to special environment of frozen earth area and increased drastically running speed. Researching techniques and measures can provide technical support for high-speed railway construction. First, this paper introduced design ideas and design objectives of durability of concrete between China and foreign and the analysis of comparison of experiments methods. Secondly, according to the research of the durability of concrete in frozen earth,through optimization design of materials of concrete can product durability of concrete. Finally, this paper researches the working principle of the controlled permeability formwork liner. The details will shows following:1、By comparing the difference between China and foreign of design ideas, objectives and experiments methods: there is no perfect method of proportion design of concrete that recognized, which under the stage of research and experiments; it is easily find that the some limit values in standard of China are lower than other countries. However, limit values could be corrected and modified with experiments instead of copy foreign standard without destination. This will not only satisfied the requirements of durability of building but also reduced waste of materials.2、According to the features of structure of HSR line, there is a optimal decision of concrete C50 proportion through modifying different proportion of concrete and orthogonal test: water-binder ratio is 0.31, cement: fly ash: micro-silica: large stone: micro-aggregate: sand: water: polypropylene fiber=320:75:75:30:678: 452:664:155:1.3、According to the analysis of key factors that affect concrete durability, frost resistance and permeability resistance, and combined with the working principle of permeable formwork cloth that research the influence of controlled permeability formwork liner on concrete durability increasing by strength test, durability test and microstructure analysis. This research finds out that effect principle of controlled permeability formwork liner effect on concrete durability increasing.4、Through compression test, surface rebound strength test, freeze-thaw cycle test, carbonation resistance test, mercury intrusion porosimetry(MIP), and microscopic test, it is consequently find that the cube crushing strength of durable concrete with modified proportion, polypropylene fiber and construction technology of controlled permeability formwork liner is higher than normal concrete by 29.67%, surface rebound strength increased by 27%, the ability of freeze-haw resistance raised by 27%, resistance of carbonate increased by 77.7%, porosity decreased by 29.28%.Finally, the conclusion of this research figured out that problems and limitations in this project and discussed the direction of this research in the future.