A Numerical Method For Prediction Of The Water Permeability Of Concrete

The water permeability of concrete is a key parameter for estimating the durability of concrete structures. Therefore, it is of great significance to study the pore structures and cracks of concrete and the water transport mechanism in concrete materials and to evaluate the water permeability of concrete for the prediction and design of the service life of reinforced concrete structures.The finite difference method for solving two-dimensional incompressible viscous flow of the Navier-Stokes equations is introduced in this thesis. A unit cell is adopted to simulate fluid flow in concrete. By solving the fluid velocity and pressure fields using the artificial compressibility algorithm, a numerical method is presented for prediction of the water permeability of concrete and the validity of the numerical method is verified. The effects of aggregate shape, the aggregate area fraction, the aspect ratio and inclination angle of elliptical aggregates on the relative water permeability of concrete are evaluated.By introducing periodic boundary conditions, a simulation method is described for the distribution of circular aggregate particles and random cracks in a two-dimensional concrete unit. Based on the simulated mesostructure of concrete, the characteristics of crack tortuosity in concrete are studied and the effects of the aggregate area fraction, maximum and minimum aggregate sizes, and aggregate gradation on the crack tortuosity in concrete are evaluated in a quantitative manner.Based on the developed numerical method, the water permeability for straight, circular arc, and random cracks is discussed and the effects of the crack width, maximum and minimum aggregate diameters, and aggregate gradation on the water permeability of concrete cracks are quantitatively evaluated.