Development of a new cementless binder for marine dredged soil stabilization: Strength behavior, hydraulic resistance capacity, microstructural analysis, and environmental impact

The primary goal of this study is to evaluate the strength behavior, hydraulic resistance capacity, microstructure, and environmental impact of marine dredged soil (MDS) after stabilization and its improvement without the use of cement. In this study, a new cementless binder, referred to as Fa-RmLG, was derived from fly ash (Fa), lime (L), gypsum (G), and red mud (Rm). During the MDS stabilization stage, a pilot experimental program (phase I) was conducted to identify the optimum water content in mixtures. Subsequently, MDS mixtures were synthesized with various proportions of Fa-RmLG, and the optimum water contents were determined (phase II). The general properties of MDS mixtures, including strength, stiffness (evidenced by the secant modulus), and hydraulic resistance capacity (e.g., critical shear stress, critical velocity, and scour rate), microstructure, and environmental impact (e.g., corrosivity, heavy metals), were measured. As a result, all general properties of the stabilized MDS mixtures demonstrated significant improvements (strength, stiffness, and hydraulic resistance capacity) as compared to those of the untreated MDS. In addition, in terms of environmental impact, it was found that the hardened MDS mixtures made with the new cementless binder were classified as nonhazardous materials as their corrosivity and heavy metal leachates were within the acceptable ranges listed in the Code of Federal Regulations of the US government (40 CFR 268.40). In conclusion, the feasibility of using the developed Fa-RmLG binder for the stabilization of MDS has been proven.