Abstract:

The particles aggregation states and apparent volume of the stacked glass beads at different liquid content are studied experimentally. It shows that the liquid mainly exist as liquid bridges at low liquid content, while that in different pores connects to each other at higher liquid content. The apparent contact angle of water on particle surface determines the critical moisture content which separates the low and high moisture content. The transformation of liquid morphologies induces the variation of the liquid action on particles, which finally influences the particles aggregate state and leads to the change in the sample apparent volume. A model is developed to determine the critical liquid content by the apparent contact angle, from which the liquid begins to mainly exist as interconnectedness morphology other than isolated liquid bridges. The prediction from the model is in good agreement with the experimental data.

Key words: porous medium, mesoscale, morphology, contact angle, critical liquid content

摘要：

实验研究了不同含湿率时堆积颗粒聚集状态和试样表观体积的变化,并分析了内在影响机理。含湿率较低时液体在试样内部的主要存在形式为液桥,含湿率较高时液体主要以联通液的形式存在,两种形态水分发生转换的临界含湿率由水在颗粒表面的表观接触角决定。试样内部液体形态及分布的演化,导致液体对颗粒的作用力发生变化,进而影响颗粒的聚集状态以及试样的宏观表观体积变化。利用建立的模型推导了液体形态发生转换的临界含湿率与表观接触角之间的函数关系,计算结果与实验具有较好的一致性。

关键词: 多孔介质, 介尺度, 形态, 接触角, 临界含湿率