Sample Preparation — the First Step of Successful Research

Abstract

The overall goal of our research project is to study the unfrozen water mass and mobility in frozen soils. Frozen samples of standard clays with different adsorbed cations will be analyzed to determine their surface potential, micro-fabric, and how they interact with unfrozen water. To be successful, our first step was to develop standard procedures for sample preparation. During the past six months, we have developed and tested a set of methods for preparing clay samples, which included crushing source rocks into clay- sized samples with a suitable grain size distribution and exchanging cations for each type of clay. We experimented with different crushing methods, including using a ball mill, and mortar and pestle. Repeatable hydrometer test results indicated that our final combination of methods will produce clay samples with grain size distributions that are acceptable for future testing. Next, we exchanged the adsorbed cations with Ca2+, Mg2+, K+, and Na+ using chloride salt solutions, and flushed the excess chloride from the soil. Each cation-saturated clay required a different number of flushes due to the changes in surface chemistry. Sample preparation may seem simple, but all great research begins with a sound scientific foundation.