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Impact of Gypsum Bearing Water On Soil Subgrades Stabilized With Lime or Portland Cement

Mohn, Douglas M
http://rave.ohiolink.edu/etdc/view?acc_num=akron1430836216

Abstract Details

2015, Master of Science in Engineering, University of Akron, Civil Engineering.
Use of calcium based stabilizes to enhance clay’s engineering properties is a common practice in road subgrade improvement. The addition of a calcium based stabilizer increases the calcium content of the soil to reduce the diffuse double layer by cation exchange and leads to flocculation and agglomeration of the clay microstructure. The addition of calcium hydroxide (Ca(OH)2) allows cementitious hydrates to form, via pozzolanic reactions, that increase soil strength. Problems can arise when sulfate and alumina are readily available within the natural state of the soil. Reactions can occur that produces the ettringite mineral that can facilitate sulfate induced heave depending on the amount formed. Although sulfate induced heave is caused by ettringite, ettringite is not a direct correlation to heave. Meaning, the presence of ettringite does not automatically indicate swell since ettringite is a necessary component that increases the strength of cement. Ettringite is only problematic when formation occurs after the mineral consumes all available void space. When this occurs, the ettringite mineral will exert and outward pressure from within the soil and cause heaving of the soil. The ultimate goal of this research was to determine if sulfate concentration in water can contribute to, or even cause, sulfate induced heave. There were four tasks identified to achieve this goal: 1) obtain soil samples from areas of concern, 2) subject soil to mechanical and chemical characterization, 3) chemically stabilize soils and subject to swell test, and 4) asses dominant or limiting factor(s) associated with heave by comparison of pre and post characterization. Results demonstrated that pure kaolinite stabilized with 4% lime will swell excessively when subjected to water. Lime and cement stabilization proved successful when swell was below the set threshold of acceptable swell of 1.5%, as set by ODOT Supplemental 1120. Excessive swell was experienced by a high sulfate (SO4) soil that tested positive for gypsum when stabilized with either lime or cement. Cement stabilization of the high SO4 soil exhibited maximum swell being reached three times faster and a higher unconfined compression failure strength than lime stabilization of the same soil. The saturated gypsum water subjected to the stabilized soil had numerically higher swells than stabilized soil subjected to distilled DI water, but was not statistically proven (p>0.05). All soils stabilized, with the exception to kaolinite, had ettringite within the soil with the amount formed varying.
Teresa Cutright, Dr. (Advisor)
Ala Abbas, Dr. (Advisor)
John Senko, Dr. (Advisor)
183 p.
Civil Engineering

Recommended Citations

Citations

  • Mohn, D. M. (2015). Impact of Gypsum Bearing Water On Soil Subgrades Stabilized With Lime or Portland Cement [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430836216

    APA Style (7th edition)

  • Mohn, Douglas. Impact of Gypsum Bearing Water On Soil Subgrades Stabilized With Lime or Portland Cement. 2015. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1430836216.

    MLA Style (8th edition)

  • Mohn, Douglas. "Impact of Gypsum Bearing Water On Soil Subgrades Stabilized With Lime or Portland Cement." Master's thesis, University of Akron, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1430836216

    Chicago Manual of Style (17th edition)

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