不同骨料级配透水混凝土的性能研究及其孔隙识别

依据体积堆积理论采用5~10、10~15、15~20 mm单粒级的碎石骨料设计和配制孔隙率分别为15%、20%、25%的透水混凝土，利用相关数学模型探究实测孔隙率与透水混凝土性能相关性，通过平面孔隙二值化识别透水混凝土内部孔隙结构特征。结果表明:透水混凝土的实测孔隙率能达到设计孔隙率的90%以上，与表观密度呈现良好的线性关系，与透水系数和抗压强度均呈现良好的幂函数关系。设计孔隙率的变化对骨料粒径较小的透水混凝土的透水性能影响较大，较小的骨料粒径有利于增加透水混凝土的28 d抗压强度，较大的骨料粒径有利于增加透水混凝土的透水系数。设计孔隙率与骨料粒径的增大均能使透水混凝土内部孔隙等效直径增大，降低孔隙曲折度，改变骨料级配，但骨料粒径的影响作用更为明显，二者的作用机理不同。

Properties of Pervious Concrete with Different Aggregate Gradations and Its Pore Identification

Three kinds of single-grained gravel aggregates of 5-10，10-15 and 15-20 mm were used to design and prepare pervious concrete （PC） with porosity of 15%，20% and 25% using a volumetric method. We studied correlation between the measured porosity and the performance of PC by mathematical model，and the pore structure of PC was determined by the planar pore binarization. The experimental results show that the measured porosity of PC can reach more than 90% that of the designed demonstrating a good linear relationship with the apparent density，and a good power function relationship with both permeability coefficient and compressive strength. The designed porosity and the aggregate size are important factors affecting the performance of PC. The smaller aggregate size is beneficial to increasing the 28 d compressive strength of PC，while the larger aggregate particle size is beneficial to increasing the permeability coefficient of PC. The increase in designed porosity and aggregate size can increase the equivalent diameter of internal pores of pervious concrete，reduce the porosity tortuosity，and change the aggregate gradation，however，the effect of aggregate particle size is more obvious，and the mechanisms of their actions are different.