The Concrete Carbonation Depth Prediction Research Based On The Modle Of Similarity Theory

With the development of the industrialization process,the atmospheric CO₂ concentration is rising,the concrete carbonation has become one of the important factors affecting the durability of reinforced concrete structure.The carbonization model established by the existing concrete carbonation research methods is mainly based on the theoretical model of diffusion theory and empirical model based on carbonization test or engineering data.The rapid carbonization test can study the relationship between the influence conditions and the depth of concrete carbon by controlling the temperature,humidity and CO₂ concentration.This method can shorten the carbonization time and reduce the test cost.However,due to the difference between the environment of concrete in the rapid carbonation test and the carbonation conditions under natural conditions,the results of the study do not fully reflect the actual carbonization.By establishing the numerical relationship between natural carbonation and rapid carbonization,this paper can improve the accuracy of rapid carbonization test and can reflect the actual situation of concrete carbonization more accurately.In order to find the quantitative relationship between natural carbonation and rapid carbonization,this paper studies the microscopic direction based on the macroscopic direction based on multivariate nonlinear summation and the theoretical direction based on diffusion theory.?1?The data of the laboratory have been analyzed and carbonized for long time.?2?Using the multivariate nonlinear research method,the experimental data are processed,and the rapid carbonation depth prediction model and the natural carbonation depth prediction model of concrete based on multiple nonlinear research are established respectively.Based on the rapid carbonation depth prediction model and the natural carbonation prediction model,the carbonation time proportional model and the carbonation depth ratio model between natural carbonation and rapid carbonization were established.?3?According to Fick's first law,the diffusion coefficients of different carbonation times and different carbonization times were established.Based on the concrete compressive strength of natural carbonization and rapid carbonization,considering the mixing ratio and the combination ratio The diffusion coefficient model is established and the carbonation depth prediction model of concrete corresponding to the diffusion coefficient is established.?4?According to the basic theory of diffusion of carbonation of concrete,the natural carbonation and rapid carbonation arrays with the same depth of carbonization were selected.The ratio of temperature ratio coefficient,ratio of CO₂ concentration ratio and water-cement ratio were established between natural carbonation and rapid carbonization And the fly ash content ratio coefficient of carbonation time proportional relationship model.?5?Select the carbonation time of 28 d natural carbonation and rapid carbonation array.The relationship between the multi-factor influence coefficient and the water-cement ratio,the fly ash content,the concrete compressive strength,the water-cement ratio and the fly ash production and the water-cement ratio and the fly ash deformation coefficient were established.Based on the carbonization depth ratio relationship model.?6?Based on the data obtained from the natural carbonation test of long time,the model of the two methods was tested and compared.The results show that both models can be used for carbonization depth prediction and the carbonation time ratio model and the carbonization depth ratio model High degree of coincidence.