ABSTRACT The aim of this study is to evaluate the strength characteristics of MDS stabilized with cementless binder developed from industrial by-products in Honam area. The new cementless binder, tentatively named Fa-RmLG, derived from a cementitious mixture composed of various industrial by-products such as fly ash (Fa), red mud (Rm), lime (L) and gypsum (G) is proposed and employed. Various mixtures of MDS were prepared with different proportions of Fa-RmLG. The settlement, leaching of heavy metals and the most important property, unconfined compressive strength were evaluated. As a result, an extremely large increase in strength was obtained from the stabilized MDS mixtures when comparing to the untreated MDS ones. The proposed Fa-RmLG binder was found to be feasible to solidify MDS.
INTRODUCTION Dredging operations are necessary to maintain navigation in waterways and access to harbors. Large volumes of sediments are dredged every year in Korea for harbor activities. However, the management of these marine dredged sediments (MDS) has become increasingly complex recently. More than ever, finding an alternative use of these materials in geotechnical applications is essential for a reduction of environmental pollution and sustainability contribution. Therefore, there have been significant interests in the reuse of MDS as alternative materials in road pavement works of onshore constructions in Korea. Meanwhile, large amounts of industrial by-products are produced annually from thermal power plants and chemical industries in Korea, recently. Among them, coal ash and gypsum are the main wastes produced in large quantities. The disposal of these wastes will be a big challenge in the near future for Korea to decrease the harmful environmental effects (e.g., generation of respirable particulate matter and pollution of soil and water due to leaching of heavy metals). For that purpose, it is ideal to develop a new cementless binder derived from industrial by-products (e.g., fly ash, red mud, and gypsum) for MDS stabilization. However, it is necessary to test the feasibility of this solution to construction standards, environmental and human health requirements. Fly ash is a by-product of burning pulverized coal in a thermoelectric power plant. Specifically, it is the unburned residue that is carried away from the burning zone in the boiler by the flue gasses and then collected by either mechanical or electrostatic separators. In Korea, around 60% of fly ash is beneficially reused, and the largest markets for the reuse of fly ash are the cement and concrete industries. However, recent fly ashes in Korea contain relatively high content of unburned carbon particles; thus, it is expected that the amount of disposed fly ash in Korea is increasing due to the regulation of ASTM C618 (Choo et al., 2016).