Condition Evaluation of In-Service Chemically Stabilized Subgrades in a High Sulfate Environment
This project included measurements of strength properties, soil properties, and chemical content of natural and chemically stabilized subgrade soil from five projects across Ohio, three from sites that have historically had high sulfate content, and two that have not. The objective was to compare the properties of the soils from the sites and determine if there were crystals of ettringite or thaumasite in the soil, which would indicate potential for heaving. Site testing included portable seismic properties analyzer (PSPA), falling weight deflectometer (FWD), lightweight deflectometer (LWD), dynamic cone penetrometer (DCP), standard penetration testing (SPT), an informal distress survey, and collection of soil specimens for laboratory analysis, which included standard soils tests (Grain size, Atterberg limits, organic content, moisture content, pH, and sulfate content as determined in Ohio Supplement 1122), and chemistry analysis comprising neutralization potential, and X-ray diffraction. In the control sections, measured sulfate levels were low in the natural subgrade and higher in the stabilized subgrade but still below the criterion of concern at 3000 ppm. In the high sulfate sections, natural subgrade had still higher sulfate content, but still usually below 3000 ppm, while the stabilized subgrade generally had content above 3000 ppm, but no more than 6500 ppm to 9500 ppm depending on the site. However, the X-ray diffraction found no measurable quantity of ettringite or thaumasite crystals, indicating that conditions for formation were not met at any of the sites. The pH of stabilized soil at all locations was just above 10, which was one condition that was met. None of the pavements showed any signs of damage due to sulfate heaving. The continued practice of global stabilization of subgrade soil is recommended. The undercut section on LAK-2 showed less variability than the other section, and this approach may be considered where cost effective.
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- Summary URL:
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Corporate Authors:
Ohio University, Athens
Ohio Research Institute for Transportation and the Environment
141 Stocker Engineering and Technology Center
Athens, OH United States 45701-2979Ohio Department of Transportation
Columbus, OH United States 43216-0899Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC United States 20590 -
Authors:
- Sargand, Shad
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0000-0002-1633-1045
- Khoury, Issam
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0000-0003-4856-7535
- Daniels, Natalie Kruse
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0000-0002-8684-1315
- Green, Roger R
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0000-0003-2497-825X
- Redinger, Dane
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0000-0003-3334-6377
- Jordan, Benjamin
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0000-0003-3902-0802
- Kennedy, Kalub
- Publication Date: 2018-1
Language
- English
Media Info
- Media Type: Digital/other
- Edition: Final Report
- Features: Appendices; Figures; Maps; Photos; References; Tables;
- Pagination: 216p
Subject/Index Terms
- TRT Terms: Condition surveys; Ettringite; Frost heaving; Soil stabilization; Soil tests; Subgrade (Pavements); Sulfates
- Uncontrolled Terms: Thaumasite
- Geographic Terms: Ohio
- Subject Areas: Geotechnology; Highways; Pavements;
Filing Info
- Accession Number: 01685236
- Record Type: Publication
- Report/Paper Numbers: FHWA/OH-2017/41
- Contract Numbers: State Job No. 135443
- Files: NTL, TRIS, ATRI, USDOT, STATEDOT
- Created Date: Nov 12 2018 5:15PM