基于孔结构参数的混凝土气体扩散模型

Gas Diffusion Model in Concrete Based on Pore Structural Parameters

关键词:  混凝土  分形维数  气体扩散系数  水饱和度

Key words:  concrete  fractal dimension  gas diffusion coefficient  water saturation

摘要:

提出了一种反映混凝土孔结构特征的毛细管束几何模型，并运用分形维数表征了孔数目、孔隙率和曲折度等参数.通过水饱和度与气体有效扩散空间的关系，建立了考虑水饱和度影响的混凝土气体扩散模型，并运用该模型分析了水饱和度、水灰比和环境温度等对气体扩散系数的影响.结果表明：水饱和度是影响混凝土中气体扩散性能的一个主要参数，当水饱和度达到85%（质量分数）时，对气体扩散系数的影响最为显著.

Abstract:

A geometric model of capillary tubes was proposed to characterize the pore structure of concrete. The pore structure parameters, such as pore number, porosity and tortuosity, were represented as functions of the fractal dimension. Depending on the relationship between water saturation and effective space for gas diffusion, the gas diffusion model in concrete was established. Numerical simulations were carried out to investigate the effects of water saturation, water cement ratio and environmental temperature on the gas diffusion coefficient in concrete. Results show that, water saturation is the main parameter influencing the gas diffusion coefficient in concrete. When the water saturation is of 85%(by mass)，the effect is more significant.