Experimental evaluation of the pore-access size distribution of sands

A simple experimental method is presented for evaluation of the pore-access size distribution of sands and, more generally, of cohesionless granular materials. The water-retention curve of a sand specimen is evaluated using a technique similar to the hanging column method (ASTM 2008) [ASTM D6836: Standard Test Methods for Determination of the Soil Water Chararcteristic Curve for Desorption Using a Hanging Column, Pressure Extractor, Chilled Mirror Hygrometer, and/or Centrifuge, Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2008] by application of a step-by-step variation of suction and measure of the corresponding changes in water content. The pore-access size distribution is then evaluated from the water-retention curve using the Young-Laplace law, which links the suction to the pore-access radius. The efficiency of this experimental method is demonstrated by studying the influence of various parameters such as the shape and the size of the grains, the spreading of the grain-size distribution, and also the relative density of the specimen on the pore-size distribution.