Numerical solution and damage evaluation for cast-in-situ piles exposed to external sulfate attack: Fid-Bau Portal

Numerical solution and damage evaluation for cast-in-situ piles exposed to external sulfate attack

Xie, Feng / Li, Jingpei / Li, Lin / Zhao, Gaowen / Yao, Minbo

Highlights • Numerical model is capable of describing the diffusion process of concrete cast-in-situ pile exposed sulfate attack. • Numerical solution and stability were presented for the diffusion equation in the cylindrical coordinates. • Damage evolution model was proposed for the cast-in-situ pile under sulfate attack. • Pile radius and w/c showed an obvious impact on the durability for the cast-in-situ pile.

Abstract This paper presented a numerical model and a damage evolution model for cast-in-situ concrete piles under external sulfate attack. Based on Fick’s second law and chemical reaction kinetics, a diffusion-reaction model for describing the time-dependent diffusion behaviour of cylindrical piles exposed to external sulfate was obtained. Then, in order to maintain numerical stability, an improved numerical method using the Crank-Nicolson scheme was presented. Experiments using concrete cylinders exposed to sulfate were executed to validate the diffusion model and numerical method and revealed that the numerical solution was capable of ensuring the stability of the numerical computation and obtaining values that were in agreement with the experimental data. Finally, a damage evolution model was introduced for the chemical damage caused by the ettringite growth. Moreover, the proposed damage model was employed to predict the compressive concrete strength responses to changes in relevant factors, including the pile diameter, sulfate ion concentration and water to cement ratio.