Method for obtaining chlorine ion diffusion and combination parameters in cement-based material

Abstract

The invention discloses a method for obtaining chlorine ion diffusion and combination parameters in a cement-based material. The method only needs a total chlorine ion concentration curve, and can simultaneously obtain a chlorine ion effective diffusion coefficient and adsorption isothermal curve parameters through regression calculation. The method comprises the following steps: obtaining a total chlorine ion concentration distribution curve by a non-steady state diffusion test; trying different combinations of to-be-obtained parameters, calculating to obtain a theoretical total chlorine ion concentration distribution curve; carrying out fitting regression of the theoretical curve and the experimental curve by a nonlinear least square method, to obtain a set of parameter values with the highest fitting degree; calculating the confidence interval of each parameter; and further calculating to obtain an adsorption curve, distribution curves of an apparent diffusion coefficient along with the time and space, and distribution curves of total chlorine ions, combined chlorine ions and free chlorine ions in the time and space. The method not only can obtain the diffusion parameter and the combination parameter, but also can obtain the intervals of the parameters.

Description

technical field [0001] The invention relates to a method for obtaining chloride ion diffusion and combination parameters in cement-based materials, and belongs to the field of durability measurement of cement-based materials. Background technique [0002] Corrosion of concrete reinforcement due to chloride ion attack is an important durability issue. In general, chloride ions will be adsorbed and combined with the cement matrix during diffusion and transport, which will reduce the diffusion rate of chloride ions and reduce the concentration of chloride ions on the surface of the steel bar. Although free chloride ions are mainly responsible for controlling corrosion, and combined chloride ions will transform into free chloride ions under certain conditions, so it is of great significance to study the combination and diffusion of chloride ions for the corrosion durability of steel bars in civil engineering structures. [0003] The diffusion ability of chloride ions is usually...

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Problems solved by technology

The equilibrium method cannot reflect the diffusion process; for the natural diffusion method, the acid solution method can obtain a more accurate total chloride ion concentration, but there is a systematic error when the free chloride ion is measured by the water solution method or the filter press method; the diffusion cell method has a long test cycle ; The electromigration method will be affected by the electric field

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