Regression analysis for determination of durability parameter values of marine concrete

The importance of determination of marine concrete durability and lifetime prediction parameters through regression analysis of exposure test results or field measurements is discussed. The parameters considered include the apparent diffusion coefficient, the apparent surface chloride content and the time attenuation coefficient of the apparent diffusion coefficient. According to the analytical expression of Fick's second law, the essential features and the procedure of regression analysis (curve fitting) of chloride profiles are analysed. A new curve-fitting approach for determination of the parameters of marine concrete durability, called the secondary regression analysis method (Sram), is proposed. In this method, the first regression step is to determine the values of the apparent diffusion coefficient and the apparent surface chloride content. Based on the regression results of the vector of different exposure times, the second step is to determine the value of the time attenuation coefficient of the apparent diffusion coefficient and the change of apparent surface chloride content with respect to time. In the first step, the integral transformation method is analysed and used. In the second step, the non-linear equation is transformed into a linear equation. An example calculation shows that the Sram is a new approach for determination of marine concrete durability parameters.