Evaluating the Durability of Lime-Stabilized Soil Mixtures using Soil Mineralogy and Computational Geochemistry

Lime stabilization is a common technique used to improve the engineering properties of clayey soils. The process of lime stabilization can be split into two parts. First, the mobilization and crowding of Ca2+ ions or Ca(OH)2molecules from hydrated lime at net negative surface charge sites on expansive clay colloids. Second, the formation of pozzolanic products including calcium-silicate-hydrate (C-S-H) because of reactions within lime-soil mixtures. The pozzolanic reaction is generally considered to be more durable, while the calcium adsorption has been associated with more easily reversible consistency changes. This study offers a protocol to assess whether the stabilization process is dominated by durable C-S-H (pozzolanic) reactions or a combination of cation exchange and pozzolanic reactions. Expansive clays with plasticity indices >45% from a major highway project in Texas are the focus of lime treatment in this study. The protocol consists of subjecting lime-soil mixtures to a reasonable curing period followed by a rigorous but realistic durability test and investigating the quality and quantity of the pozzolanic reaction product. Mineralogical analyses using quantitative X-ray diffraction (XRD) and thermogravimetric analysis (TGA) indicates the formation of different forms of C-S-H. In addition, geochemical modeling is used to simulate the lime-soil reactions and evaluate the effect of pH on the stability of C-S-H. The results indicate C-S-H with Ca/Si ratio of 0.66 as most the stable form of C-S-H among other forms with Ca/Si ratio ranging from 0.66 to 2.25. The effect of reducing equilibrium pH on C-S-H is also evaluated. A reduction in pH favored dissolution of all forms of C-S-H indicating the need to maintain a pH?=?10.

• Record URL:
  • https://doi.org/10.1177/03611981211007848
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/03611981
• Supplemental Notes:
  • © National Academy of Sciences: Transportation Research Board 2021.
• Authors:
  • Akula, Pavan
  • Naik, Saureen Rajesh
  • Little, Dallas N
• Publication Date: 2021-9

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: pp 1469-1481
• Serial:
  • Transportation Research Record: Journal of the Transportation Research Board
  • Volume: 2675
  • Issue Number: 9
  • Publisher: Sage Publications, Incorporated
  • ISSN: 0361-1981
  • EISSN: 2169-4052
  • Serial URL: http://journals.sagepub.com/home/trr

Subject/Index Terms

• TRT Terms: Calcium hydroxide; Clay soils; Durability; Geochemistry; Geophysics; Highways; Mineralogy; Pozzolanic action; Soil stabilization; Stabilized materials; Swelling soils; Thermogravimetric analysis; X ray analysis
• Geographic Terms: Texas
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 01763780
• Record Type: Publication
• Report/Paper Numbers: TRBAM-21-03000
• Files: TRIS, TRB, ATRI
• Created Date: Feb 4 2021 10:57AM