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Title: HYDRATED LIME STABILIZATION OF SULFATE-BEARING VERTISOLS IN TEXAS
Accession Number: 00978555
Record Type: Component
Record URL: Availability: Transportation Research Board Business Office 500 Fifth Street, NW Find a library where document is available Abstract: Sulfate-bearing subgrade soils treated with calcium-based stabilizers often experience heaving problems (three-dimensional swell) caused by chemical reactions with the sulfate or sulfide minerals. Two research questions were addressed: (a) what sulfate content results in deleterious chemical reactions using traditional (no mellowing) lime stabilization and (b) how effective mellowing, double lime application and increased moisture content are at reducing swell in high-sulfate soils. To determine what concentrations of sulfate are too high for stabilization with lime in Texas, a soil from the Vertisol order was selected for three-dimensional swell measurements. This soil did not contain any detectable sulfates. Two different compounds were added to the soil: sodium sulfate (Na2SO4) and gypsum (CaSO4-2H2O). The sulfates were added to individual samples at concentrations of 0; 1,000; 2,000; 3,000; 5,000; 7,000; and 12,000 parts per million (ppm). The samples were then subjected to a three-dimensional swell test for a minimum of 45 days. Results of systematic swell experiments revealed that sulfate contents up to 3,000 ppm could safely be treated with traditional lime stabilization. Coarse-grained sulfates take longer to swell, but still swell and form deleterious reaction products. Mellowing is effective at treating sulfate concentrations up to at least 7,000 ppm, higher molding moisture contents (2% above optimum moisture) reduce swell better than optimum moisture, and single application of lime reduces swell better than double application. With systematic laboratory experiments, empirical field observations of sulfate limits presented by other investigators were confirmed.
Supplemental Notes: This paper appears in Transportation Research Record No. 1868, Soil Mechanics 2004.
Monograph Title: Monograph Accession #: 00978551
Language: English
Corporate Authors: Transportation Research Board 500 Fifth Street, NW Authors: Harris, J PSebesta, SScullion, TPagination: p. 31-39
Publication Date: 2004
Serial: ISBN: 0309094623
Features: Figures
(8)
; References
(17)
; Tables
(1)
TRT Terms: Uncontrolled Terms: Geographic Terms: Subject Areas: Geotechnology; Highways; I42: Soil Mechanics
Files: TRIS, TRB, ATRI
Created Date: Sep 27 2004 12:00AM
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