In an effort to increase the utilization of by-product materials in highway construction projects, the Kentucky Transportation Cabinet authorized the experimental use of residue from an atmospheric fluidized bed combustion (AFBC) process and multicone kiln dust (MKD), a by-product resulting from the production of lime, as subgrade soil modifiers. This report presents information relative to preconstruction and post-construction laboratory evaluations, construction procedures, construction monitoring activities, and performance evaluations of a highway subgrade soil modified using AFBC spent lime, MKD, Type 1P cement, and hydrated lime. An untreated section served as a control section for the project located on Kentucky Route 11 in Lee and Wolfe Counties. The laboratory testing program consisted of determining select engineering properties of the soil in a natural state and in a state altered by the chemical admixtures. Index tests were performed, moisture density relationships were determined, and bearing ratio and swell tests were performed. Based on the laboratory unconfined compression tests and bearing capacity tests, the two waste by-products significantly improved the shear strength and bearing strength of the subgrade soil. Field monitoring activities were comprised of both construction monitoring and post-construction monitoring. Construction procedures were essentially the same for all admixture types and no significant problems were encountered. Satisfactory moisture and density were achieved. Construction activities were documented through moisture content and density compliance tests. In-place bearing capacity tests and Road Rater deflection tests were performed on the untreated subgrade and again after modification. The analyses indicated significant improvement in subgrade strength after admixture modification. Post-construction monitoring included determining in-situ bearing capacities, assessing moisture conditions and determining soil classifications of the treated and untreated subgrade layers. Road Rater deflection tests were conducted to assess the structural condition of the pavement structure. Results of the field monitoring program confirmed that each chemically modified subgrade continued to exhibit greater strength than the untreated subgrade section. However, because of non-uniform mixing, the soil-AFBC subgrade sections exhibited severe differential swelling shortly after construction. The bituminous pavement required milling to eliminate humps on the pavement surface. The pavement was overlaid and apparently the subgrade swelling has ceased. However, due to the expansive nature of the AFBC spent lime, future use as a soil modifier could not be recommended. Results of field monitoring activities indicated that MKD was a suitable soil modifier and future use was recommended.

  • Record URL:
  • Supplemental Notes:
    • See also KTC-89-56, "Preliminary Engineering, Monitoring of Construction, and Initial Performance Evaluation: Use of Ponded Fly Ash in Highway Road Base".
  • Corporate Authors:

    University of Kentucky, Lexington

    Kentucky Transportation Center
    College of Engineering, 176 Raymond Building
    Lexington, KY  United States  40506-0281

    Kentucky Transportation Cabinet

    200 Mero Street
    Frankfort, KY  United States  40622

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Hunsucker, D Q
    • Hopkins, T C
    • Beckham, T L
    • Graves, R C
  • Publication Date: 1993-1


  • English

Media Info

  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 125 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00670457
  • Record Type: Publication
  • Report/Paper Numbers: KTC 93-4, NCP 4E2B5042
  • Contract Numbers: KYHPR-87-117
  • Created Date: Dec 22 1994 12:00AM