Technical gazette, Vol. 27 No. 6, 2020.
Original scientific paper
https://doi.org/10.17559/TV-20200530041557
Numerical Simulation of the Ion Transport Behavior in Concrete under Coupled Axial Loading and Sulfate Attack
Wenzheng He
; 1) School of Civil Engineering, Chongqing Jiaotong University, 2) School of Urban Construction Engineering, Chongqing Radio & Television University, No.15 Siyuan Road, Hechuan District, Chongqing, China
Linsheng Xu*
; School of Civil Engineering, Chongqing Jiaotong University, No.66 Xuefu Road, Nanan District, Chongqing, China
Lili Wang*
; School of Management, Cardiff Metropolitan University, Llandaff Campus, Western Avenue, Cardiff,CF5 2YB, Wales
Abstract
During a sulfate attack on concrete, ions, which are transported to the interior of concrete through pores, react with the concrete components. The transport characteristics are affected by various factors. A chemical-mechanical coupling method for accurately evaluating the transport behavior of sulfate ions in concrete under stress conditions was proposed in this study to investigate the transport characteristics of these ions. The diffusion-reaction equations of sulfate ions were obtained based on the diffusion-reaction approach in combination with the mechanism of volume expansion under a sulfate attack and the influence of load on the concrete voidage. The constitutive response and crack density of the matrix were calculated according to the volumetric strain caused by external load and ettringite growth. Then, the diffusion coefficient of the equation was dynamically corrected. T'his phenomenon was a strongly coupled moving boundary problem, and the equations were solved using numerical method. A case study was conducted to analyze the distribution law of ionic concentration and volumetric strain obtained using the proposed method. Results demonstrate that the crack damage due to volumetric strain plays a major role in the diffusion of sulfate ions. The load has minimal effect on the transport behavior under a low stress level, and the water-cement ratio is negatively correlated with ion transport capacity. The proposed method serves as a reference for evaluating the durability of an underground structure in a sulfate formation.
Keywords
concrete; coupling; diffusion; modeling; sulfate attack
Hrčak ID:
248212
URI
Publication date:
19.12.2020.
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