Utilization of mass stabilized dredged mud and clay as fill and embankment construction material, case City of Helsinki

The technical and environmental properties of stabilized dredged soft sediments have been studied thoroughly at the laboratory scale and in situ in different phases of construction - in the basin before and after stabilization and in the structure after transport and construction. The studied properties are e.g. shear strength, modulus of elasticity, hydraulic conductivity, leaching of contaminants, etc. Mass stabilization has been applied to improve the technical and environmental properties of the dredged sediment in order to be utilized as earth construction material. The high price and carbon footprint of cement binder have encouraged the use of alternative binders such as fly ash from the combustion of coal and oil shale as well as flue gas desulphurization residue. The results of the leaching tests show that the leaching of heavy metals is very low with all the binder materials tested. These stabilized sediments have been utilized as earth construction material in various construction sites such as noise barriers in the Helsinki city area.