基于分形理论的混凝土气泡分布特征研究

依托分形理论的盒维数概念,建立了气泡分布分形模型,提出了气泡分布分形维数计算方法。通过快速冻融循环试验和气泡结构分析试验测定了多组混凝土的抗冻性和气泡结构,分析了掺合料和引气剂对混凝土气泡分布特征的影响,得出了气泡分布特征随掺合料种类和引气剂掺量的变化规律。最后,分析了气泡分布分形维数与相对耐久性指数的关系,结果显示二者具有较高的正相关性,说明气泡分布对混凝土抗冻性有重要影响,可以将气泡分布分形维数作为气泡特征参数用以评估混凝土的抗冻性。

Fractal analysis of air void distribution characteristic of concrete

A fractal model was proposed for calculation of the fractal dimension of air voids size distribution based on the box fractal dimension.The rapid freezing and thawing test and the air void analyzing test were developed on a set of concrete mixtures.The influences of admixtures and air entrained agent on air void distribution characteristics were studied.The change law of air void distribution with admixture kinds and the amount of air-entrained agent were concluded.At last,the statistical relationship between freeze-thaw durability factors and fractal dimension was analyzed,and a fairly high correlation coefficient are obtained,which indicate that air void distribution has important influence on freeze-thaw resistance.The fractal dimension of air void size distribution can be used as an air void parameter to assess the freeze-thaw resistance of concrete.