Stabilized Dredged Material. II: Geomechanical Behavior

This study presents the results of a detailed geotechnical evaluation of six stabilized dredged material (SDM) blends incorporating various combinations of lime, cement kiln dust, high alkali and slag cements, and Class F fly ash. The dredged material classified as CH/OH soil with an in situ moisture content (MC) of approximately 130% and void ratio of 3.35. Mix designs and unconfined compression strength tests were completed for each SDM blend based on 3-day mellowing characteristics. Compacted dry densities were on the order of $7.8–11.2\text{kN}/{\text{m}}^3$ $\left(49–71\text{lb}/{\text{ft}}^3\right)$ , with MCs on the order of 34–73%. Peak effective friction angles ranged from 20–50° with cohesion intercepts on the order of 30–235 kPa $\left(4–34\text{lb}/{\text{in.}}^2\right)$ using a maximum stress obiliquity criterion. Postpeak effective friction angles (15% axial strain) were routinely in excess of 40° with low cohesion ( $<40\text{kPa}$ ; $6\text{lb}/{\text{in.}}^2$ ). One sample exhibited very strong soil-fabric effects (cohesion) having an effective friction angle of only approximately 9°, but cohesion on the order of 450 kPa $\left(65\text{lb}/{\text{in.}}^2\right)$ . Negligible consolidation of a 28-day cured sample was measured. Also, contrary to expectations based on the high sulfate contents (10,000–30,000 mg/kg) of the SDM blends, negligible swell $\left(<1\mathrm{\%}\right)$ was measured in five of six SDM blends. The main finding of this research is the SDM blends exhibit the strength, compressibility, and bulking characteristics that make them favorable for large fill applications and subgrade improvement applications at costs equivalent to or less than conventional construction materials.