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FreeseK.the (final comments 2).pdf (4.06 MB)

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Assessment of Sulfate in Ohio Transportation Subgrades

Freese, Kevin M
http://rave.ohiolink.edu/etdc/view?acc_num=akron1404393723

Abstract Details

2014, Master of Science in Engineering, University of Akron, Civil Engineering.
The Ohio Department of Transportation (ODOT) recently implemented global chemical stabilization for new construction or repair involving major road projects. Pavement heave caused the failure of the road surfaces in three projects in Lake County, Ohio. Subsequent soil investigation revealed surface heave was caused by soil swell from the formation of a calcium alumina sulfate hydrate, ettringite (Ca6Al2(SO4)3(OH)12•26H2O) which may occur in sulfate bearing soils chemically stabilized with lime. Failure of pavement in these three projects caused ODOT to question the whether other regions within Ohio had subgrades with high soluble sulfate concentrations. This report is an investigation into natural and anthropogenic sources of sulfate (SO4) in Ohio soils evaluated via literature review and soil testing. The ODOT provided just under 350 soil samples from 39 different counties throughout the state for assessment of soil chemistry and mineralogy. Soluble SO4, often the primary controlling factor in degree of ettringite formation, was measured within soils using colorimetric methods. Several soils were additionally tested for total metal (Al, Fe and Cr) concentrations using acid digestion and inter coupled plasma optical emissions spectrometry (ICP-OES). Total Al concentration within soils was analyzed, as Al and SO4 are the chemicals within ettringite which have their primary source as the prestabilized soil. Total Fe was assessed as a marker for potential areas where sulfate would have formed from the oxidation of pyrite (FeS2). Total Cr concentration was tested as chromate (CrO4) can be a replacement group for SO4 within the ettringite structure. Additionally initial review of literature identified chromite ore processing residue remediation as a potential source of excess SO4 in soils. Finally, soil mineralogy was analyzed via x-ray diffraction (XRD). Results indicate Lake County, Ohio is not the only region with Ohio where ODOT should expect subgrades with problematic soluble SO4 concentrations. Although further soil testing throughout the state is needed, sufficient sulfate concentration (>3,000 mg/kg) for elevated risk of sulfate-induced heave were identified in a number of soils and three key regions within Ohio: Lake County in the northeast, Paulding and Defiance counties in the northwest and Morrow County in the north central. Within both Lake County soils and the Paulding and Defiance area soils, the primary identified SO4 bearing minerals were evaporates, gypsum and anhydrite. The natural origin of these mineral is most likely glacial lacustrine deposits. However, there are anthropogenic sources which likely add SO4 to soils within these regions. The high degree of industrial activities including coal fired power plants add SO4 to soil in Lake County. Whereas the application of gypsum as a farmland amendment is the likely anthropogenic source in Paulding and Defiance counties. Gypsum and pyrite were identified as the primary and secondary sulfur bearing minerals, respectively, in Morrow County soils. The origin of pyrite within this region is from Devonian Shale bedrock. The oxidation of these pyritic shales was identified as the primary source of SO4, in the form of gypsum, in Morrow County soils.
Teresa Cutright, Dr (Advisor)
John Senko, Dr (Committee Member)
Ala Abbas, Dr (Committee Member)
161 p.
Civil Engineering; Environmental Engineering; Geochemistry; Geotechnology; Transportation
Sulfate; Soil Heave; Ettringite; Soil Swell; Subgrade; Gypsum; Pyrite; Lime Stabilization; Soluble Sulfate; Total Metal Concentration

Recommended Citations

Citations

  • Freese, K. M. (2014). Assessment of Sulfate in Ohio Transportation Subgrades [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1404393723

    APA Style (7th edition)

  • Freese, Kevin. Assessment of Sulfate in Ohio Transportation Subgrades. 2014. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1404393723.

    MLA Style (8th edition)

  • Freese, Kevin. "Assessment of Sulfate in Ohio Transportation Subgrades." Master's thesis, University of Akron, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1404393723

    Chicago Manual of Style (17th edition)

akron1404393723
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This open access ETD is published by University of Akron and OhioLINK.