Strength development and microstructural characteristics of soft dredged clay stabilized with basic oxygen furnace steel slag

Abstract

This paper presents the results of the strength development and macrostructure properties of soft dredged clay stabilized with basic oxygen furnace steel (BOS) slag, using the vane shear test, the unconfined compression test, and scanning electron microscope. The results indicate that the flowability exhibited a strong correlation with the undrained shear strength. A dormant period was observed, during which the BOS-treated clay strength did not increase during the 0.5–2 h curing times. Moreover, the strength development can be classified into three zones according to the strength increment rate in the log-log scale graph: 1) inactive zone (0.5–5 h), 2) active zone (5 h to 3 d), and 3) moderate zone (3–90 d). Empirical equations for each zone were proposed based on the volumetric solid content, initial water content, strength at 1 h of curing, and strength increment coefficients. Finally, the reticulation structure of the amorphous C-S-H gel and platy AFm phases on all samples were observed, with intergrowths of rod-like ettringite within the flat clay structure and flocculated clay-cement cluster, and the cementitious compounds became more evident with an increase in the BOS content and curing time.