Compressibility Behavior of Dunkirk Structured and Reconstituted Marine Soils

Oedometer tests were performed to determine the compression behavior of Dunkirk structured and reconstituted marine soils. The cement-/lime-treated soils can be considered as “artificially structured marine soils” that show “false over-consolidation.” The effect of additive on the compression curves and yield consolidation stress was investigated. For marine soils with a water content of 90.9%, cement content should be larger than 2% to form artificially structured soils. Cementing additive leads to a higher initial void ratio at compression starting point. increases with cement content, but a lime addition higher than 2% can not significantly increase . From the curves, Cc peaks at 4–6 times of and finally stabilizes with higher . For Cc-ωL, Cc-ω0, and Cc-e0, the relationships as Cc = 0.036(ωL − 50), Cc = 0.027(ω0 −50), and Cc = 0.9(e0 −1.48) can be found for structured marine soils. For Cc-ωL of eight clays, the upper and lower boundary can be found and expressed as Cc = 0.015(ωL −19) and Cc = 0.006ωL. To identify the effect of soil structure, the concept of Δe was introduced. Δe increases with until the maximum at , and then decreases with higher . Different intrinsic state lines were found for soils with different additives. Test data of cement-treated reconstituted soils fit the Burland's equations better than lime-treated soils.