The GAB (Guggenheim–Anderson–de Boer) equation is explored to describe the relation between equilibrium soil water content (w_equil) and water activity (relative humidity) of structured kaolinitic soils along the drying path. The equation is chosen as it has the advantage of a theoretical basis and can describe sorption behaviour of soils over a wide range of water activities. The GAB parameters evaluated from desorption experiments with de-structured specimens were successful in predicting the equilibrium water contents of structured kaolinitic specimens along the drying path. Insight into the influence of water activity on moisture desorption from structured soil specimens is obtained from energy requirements to desorb water molecules and by estimating the relative affinity (distribution constant) of water molecules for retention in soil pores or to undergo desorption.

中文翻译：

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GAB方程的结构化高岭土标本的土壤水分与水分活度关系

探索了GAB（古根海姆-安德森-德布尔）方程来描述平衡土壤含水量（w_等于）和沿干燥路径的结构化高岭土的水分活度（相对湿度）。选择该方程式是因为它具有理论基础的优势，并且可以描述在广泛的水分活动中土壤的吸附行为。通过解构样品的解吸实验评估的GAB参数成功地预测了沿干燥路径的结构化高岭土样品的平衡水分含量。通过解吸水分子的能量需求以及估计水分子在土壤孔隙中的保留或解吸的相对亲和力（分布常数），可以洞察水分活度对结构化土壤样品中水分解吸的影响。