Effects of Pore Size Distribution on Permeability and Frost Susceptibility of Selected Subgrade Materials

It is the thesis of this project that the fabric of a soil, i.e., the composition and arrangement of constituent particles, controls its engineering behavior. In addition, it is believed that the fabric can be described quantitatively by its pore size distribution. Magnitudes of properties can be predicted using pore-size distributions. Results of this study also clearly show that criteria for frost susceptibility based upon grain-size distributions are inadequate; pore-size based criteria are far superior for they acknowledge that a given soil can, and will, exist at many different pore sizes in its existence. A technique has been presented for the useful prediction of the in-service equilibrium water content of compacted clay. Pore size measurements in clean sand have been made for the first time by the use of trace amounts of thermally sensitive polymers which allow retention of the sand fabric. The results of this study suggest we are on the threshold of being able to assure a given property magnitude, in-service, of field compacted soil. The pore size distribution will allow the determination of the compaction procedures that will create the suite of properties that the engineer desires for the project. Thus it is felt that these results are of sufficient importance and promise to warrant an implementation program.