ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- Creators: Kavazanjian, Edward
In this study, laboratory techniques for the determination of soil suction were evaluated, a methodology for determination of the in-situ matric suction of a soil specimen was explored, and the mechanical response to changes in matric suction of natural clay specimens were measured. Suction-controlled laboratory oedometer devices were used to impose partial wetting conditions, similar to those experienced in a natural setting. The undisturbed natural soils tested in the study were obtained from Denver, CO and San Antonio, TX.
Key differences between the soil water characteristic curves of the undisturbed specimen test compared to the conventional reconstituted specimen test are highlighted. The Perko et al. (2000) and the PTI (2008) methods for estimating the relationship between volume and changes in matric suction (i.e. suction compression index) were evaluated by comparison to the directly measured values. Lastly, the directly measured partial wetting swell strain was compared to the fully saturated, one-dimensional, oedometer test (ASTM D4546) and the Surrogate Path Method (Singhal, 2010) to evaluate the estimation of partial wetting heave.
This thesis investigates the application of EICP in a soil collected from the Arizona State University Polytechnic campus. The surficial soil in the region is known to be a clayey sand. Both EICP and MICP have their limitations in soils consisting of a significant percentage of fines. Fine-grained soils have a greater surface area which requires the precipitation of a greater amount of carbonate to increase the soil’s strength. EICP was chosen due to not requiring any living organisms during the application, having a faster reaction rate and size constraints.
To determine the effectiveness of EICP as a method of improving a soil with a significant amount of fines, multiple comparisons were made: 1) The soil’s strength was analyzed on its own, untreated; 2) The soil was treated with EICP to determine if bio-cementation can strengthen the soil; 3) The soil had sand added to reduce the fines content and was treated with EICP to determine how the fines percentage effects the strength of a soil when treated with EICP.
While the EICP treatment increased the strength of the soil by over 3-fold, the strength was still relatively low when compared to results of other case studies treating sandy soils. More research could be done with triaxial testing due to the samples of the Polytechnic soil’s strength coming from capillarity.