Pore Size Distribution Studies

Pore-size distribution data for pores of diameters down to 0.016 μm were obtained by mercury porosimetry for a number of laboratory-prepared specimens. Statically-compacted specimens of a kaolinite, an illite, and Boston Blue Clay were evaluated, and changes in the pore-size distribution of the kaolinite were followed as a function of increasing amount of static compaction. In this clay several distinct classes of pore sizes were recognized. Initial compaction reduced the gross pore sizes without influencing the finer classes. After the elimination of the gross pores, further compaction was at the expense of an intermediate class of pores above about 0.14 μm in diameter, pores finer than this being unaffected. Specimens of the kaolinite prepared from a slurry or by sedimentation showed substantially different pore-size distributions from the compacted clay. Drying shrinkage tended to eliminate the larger pores while leaving the smaller ones unaffected. Pore-size distribution appears to be a sensitive parameter with which to follow the effects of microstructural changes which may influence the engineering behavior of the material.