| There is no one definitive test to determine the dispersivity of a soil. The ones that are available carry some uncertainty and need to be compared against one another. Even so, clays may be misclassified. This error can produce hazardous results if these clays are used, for example, in levee or dam systems. However, if there was a feature characteristic of all dispersive clays, some doubt could be eliminated and clays could be used without fear of dispersivity. Scanning electron microscope (SEM) images are able to look at soil surfaces on microscopic levels and note distinct particle associations. In viewing clays of various dispersivity classifications with an SEM, samples with the same dispersivity classifications can be compared and common features can be recorded. This could eliminate some of the uncertainty that arises from any single dispersion test and minimize the time needed to make an accurate classification.;The report includes a discussion of the factors influencing the formation of a dispersive clay, the tests used to detect dispersivity, the technology behind an SEM, and the results and images obtained from the analyses. The report identifies conclusions and recommendations based on the research objectives; (1) classify samples per available dispersivity tests, (2) compare the results and assign a classification, (3) use SEM technology to view the substructure, (4) establish a relationship between a soil's substructure and its dispersivity, and (5) note the effects of a chemical additive on dispersivity using physical tests and SEM imagery. |
