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海工高性能混凝土及其使用寿命预测研究

信息来源:hunningtu.biz  时间:2005-07-25  浏览次数:410

  ABSTRACT
  In the past few years, much progress has been made in the theory study of HPC used in Marine and the prediction of its service life, but few has been achieved in engineering application technique of these theories. From the angle of engineering application, this article analysed the corrosion characteristics and damage causes of the current structural used concrete in the region of Hangzhou gulf, on the basis of on-site survey of all the Marine concrete projects in that area. Taking HPC used in Marine as research objective, this article put great emphasis on the influence of the composition cementing material system to concrete performance, and make a preliminary probe into the action mechanism of the composite effects of various mineral materials in improving the performance of concrete by laser measuring size machine and EMPA. Through experiments, the article discussed how chloride ingression in concrete will be effected by such factors as exposure time, chloride binding, environment temperature, stress and cracks conditions; and also analysed the symptoms of these factors in the model of concrete service life prediction by conference to all related research reports both home and aboard. On the foundation of abovementioned research, this paper brought up an engineering model of service life prediction of marine concrete, which is based on chloride-induced corrosion.
  The innovative research work and main conclusion are as follows:
  1. The corrosion characteristics and damage reason of the current structural used concrete in region of Hangzhou gulf have been studied and analysed. It is suggested that, under marine environment, chloride ingression is a main cause to the concrete construction breakage and therefore mostly determined the service life of concrete construction. The service life of the concrete construction is also in a large extent decided by the flunctuation of the thickness of concrete cover and the apparent diffusion coefficient Da of chloride.
  2. The influence of the composition cementing material system to concrete performance has been studied. The research results indicated that the performance of concrete, particularly the performance of resistance to chloride ingression, has been greatly improved by adding various reactive mineral materials, such as ground granulated blast furnace slag, fly ash and silica fume. As a result, the service life of the concrete construction will also be lengthened. The action mechanism of the composite effects of various mineral materials in improving the performance of concrete has been researched by the application of laser measuring size machine and EMPA. It is found out that those mineral materials composite could bring mutual advantages into action. With composition of those mineral materials, the concrete performance, particularly the performance of resistance to chloride ingression, has been improved more than any one of them alone.
  3. Experiments show that chloride ingression in concrete is influenced by many factors. The research indicated that chloride ingression is largely determined by exposure time, chloride binding, environment temperature, stress and cracks conditions, the symptoms of which could be found with the modifier of the apparent diffusion coefficient Da of chloride, in the model of concrete service life prediction.
  4. In the research of the model of the service life prediction of marine concrete, the Fick’s II laws is taken as the basic mathematics model, considering the effect elements, such as exposure time, chloride binding, environment temperature, stress and cracks conditions, and united reliability analysis method, which established the model of the service life prediction of marine concrete and its calculation software SLPMC.
  It provided scientific evidence for HPC applied in marine concrete by acquiring the necessity experiment data by the spot investigation to study the usage appearance of the current structural used concrete in region of Hangzhou gulf.
  It has a certain economical, technical and social meaning to promote an efficient use of mineral admixture so as to deepen the technique level of HPC applied in marine concrete, and accelerate the development of concrete admixture technique through the study of the composition cementing material system applied to HPC in marine and the discussion of the action mechanism of the composite effects of various mineral materials in improving the performance of concrete.
  The engineering application model of the service life prediction of marine concrete based on chloride-induced corrosion and its calculation software is established in this article by analysing all factors influencing chloride ingression and referring to some other researchers conclusions. All of those conclusions can be used to predict the service life of concrete in marine environment, provide a guiding idea for the endurance design of marine project intending to build, offer necessity basis for establishing of quantity control system of marine project in building, and predict the current structural used concrete in marine so as to establish relevant maintenance and repair scheme. In this way, it is also expected to have a certain practical meaning.
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