Numerical simulation is an effective means to study the contact dissolution of cement-based materials; but the problem regarding its 3D finite element modeling has not been effectively solved. In view of this, attempts were made to build a 3D calcium dissolution model. First of all, the governing equation of calcium ion transmission was deduced in line with the mass conservation law, and on this basis a 3D mathematical model of calcium ion transportation was built based on the solid-liquid equilibrium curve, the porosity evolvement model and the effective diffusion coefficient evolvement model. The ion exchange boundary condition is incorporated to reflect the change of calcium ion concentration at the contact boundary, which provides the basis for calculating the quantity of calcium dissolution. Furthermore, according to the Galerkin finite element method, the finite element computing scheme is derived for numerical solution of the proposed model. The proposed model and FEM program is validated with two examples. Result demonstrates that the proposed model is applicable to simulating the multidimensional contact dissolution of cement-based materials. The spatial distribution and temporal distribution of characteristic variables are obtained by the numerical test of three-dimensional contact dissolution of a cylinder specimen. In 3D state, the contact dissolution develops from the surface to the inside, the dissolution rate varies from fast to slow in the same position, and the radial dissolution rate is larger than axial dissolution rate. The research achievements offer theoretical basis and approach for analyzing the impact of dissolution of cement-based material.
Key words
cement-based material /
calcium ion transmission /
contact dissolution /
characteristic dissolution /
three-dimensional finite element model
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
References
[1] B.M.莫斯克文,Φ.M.伊万诺夫,C.H.阿列克谢耶夫等. 混凝土和钢筋混凝土的腐蚀及其防护方法[M]. 北京: 化学工业出版社, 1988.
[2] 李新宇,方坤河. 水工碾压混凝土接触溶蚀特性研究[J]. 混凝土,2002(12): 12-17.
[3] MAINGUY M, TOGNAZZI C, TORRENTI J, et al. Modelling of Leaching in Pure Cement Paste and Mortar[J]. Cement and Concrete Research, 2000, 30(1): 83-90.
[4] NAKARAI K, ISHIDA T, MAEKAWA K. Modeling of Calcium Leaching from Cement Hydrates Coupled with Micro-Pore Formation[J]. Journal of Advanced Concrete Technology, 2006, 4(3): 395-407.
[5] PHUNG Q T,MAES N,JACQUES D,et al. Modelling the Evolution of Microstructure and Transport Properties of Cement Pastes under Conditions of Accelerated Leaching[J].Construction and Building Materials,2016,115:179-192.
[6] WAN K, LI Y, SUN W. Experimental and Modelling Research of the Accelerated Calcium Leaching of Cement Paste in Ammonium Nitrate Solution[J]. Construction and Building Materials, 2013, 40(3): 832-846.
[7] REARDON E J. An Ion Interaction Model for the Determination of Chemical Equilibria in Cement/water Systems[J]. Cement and Concrete Research, 1989, 20(2): 175-192.
[8] BERNER U R. Evolution of Pore Water Chemistry during Degradation of Cement in a Radioactive Waste Repository Environment[J]. Waste and Management, 1992, 12(2): 201-219.
[9] GÉRARD B, LE BELLEGO C, BERNARD O. Simplified Modelling of Calcium Leaching of Concrete in Various Environments[J]. Materials and Structures, 2002, 35(10): 632-640.
[10]NGUYEN V H, NEDJAR B, COLINA H, et al. A Separation of Scales Homogenization Analysis for the Modelling of Calcium Leaching in Concrete[J]. Computer Methods in Applied Mechanics and Engineering, 2006, 195(52): 7196-7210.
[11]WAN K, LI L, SUN W. Solid-liquid Equilibrium Curve of Calcium in 6 mol/L Ammonium Nitrate Solution[J]. Cement and Concrete Research, 2013, 53(11): 44-50.
[12]YU Y, ZHANG Y X. Coupling of Chemical Kinetics and Thermodynamics for Simulations of Leaching of Cement Paste in Ammonium Nitrate Solution[J]. Cement and Concrete Research, 2017, 95: 95-107.
[13]ADINARAYANA K N V, SASIDHAR P, BALASUBRAMANIYAN V. Modelling of Calcium Leaching and Its Influence on Radionuclide Migration across the Concrete Engineered Barrier in a NSDF[J]. Journal of Environmental Radioactivity, 2013, 124: 93-100.
[14]SCHIOPU N, TIRUTA-BARNA L, JAYR E, et al. Modelling and Simulation of Concrete Leaching under Outdoor Exposure Conditions[J]. Science of the Total Environment, 2009, 407(5): 1613-1630.
[15]DE LARRARD T, BENBOUDJEMA F, COLLIAT J B, et al. Concrete Calcium Leaching at Variable Temperature: Experimental Data and Numerical Model Inverse Identification[J]. Computational Materials Science, 2010, 49(1): 35-45.
[16]贾 攀,佘成学. 水泥基材料渗透溶蚀有限元模拟方法研究[J]. 长江科学院院报, 2018, 36(5): 112-119.
[17]JEBLI M, JAMIN F, PELISSOU C, et al. Leaching Effect on Mechanical Properties of Cement-aggregate Interface[J]. Cement and Concrete Composites, 2018, 87: 10-19.
[18]马 强,左晓宝,汤玉娟. 环境水侵蚀下水泥净浆钙溶蚀的模拟与验证[J]. 水利水运工程学报,2017(3): 107-115.
PDF(2432 KB)
