In recent years Ground Granulated Blastfurnace Slag (GGBS) has been recognised as an essential binder for stabilising contaminated dredged sediments. Traditionally, ordinary Portland cement has been used in this application,... [ view full abstract ]
In recent years Ground Granulated Blastfurnace Slag (GGBS) has been recognised as an essential binder for stabilising contaminated dredged sediments. Traditionally, ordinary Portland cement has been used in this application, but it is now clear that GGBS has unique physical and chemical properties that make it a more suitable hydraulic binder. GGBS has a different chemical profile to
ordinary cement – lower lime, higher silica content, and lower pH. These differences impart more chemical stability and greater long term strength to stabilised sediments than traditional cements.
This presentation outlines the essential characteristics, both technical and environmental, of GGBS, covering its chemistry, physical characteristics and (due to its being an industrial co-‐product) its reduced environmental impact.
An overview of a wide selection of recent studies on the physical properties of sediments stabilised with GGBS-‐based binders is presented, covering laboratory and field trial studies on sediments from several European ports. This shows the very good strength characteristics of sediments stabilised with GGBS. This will also include the results from XRD, porosity and permeability studies that demonstrate the lower porosity and permeability achieved with GGBS, and contrasts these with that of cement.
The results of leaching tests on sediments stabilised with cement and GGBS-‐cement mixes is also presented, showing lower leaching with GGBS mixes, in particular alkali-‐activated GGBS. In support of this, the results of X-‐Ray Absorption spectroscopy is presented showing that the elemental oxidation state of heavy metals in sediments stabilised with GGBS is not changed, whereas this is changed for cement-‐only mixes.
The use of GGBS for reducing soluble sulfates in brownfield soils is also presented. This application of GGBS is being used by soil treatments contractors to re-‐classify brownfield soils under Waste Acceptance Criteria so that they can be disposed of in Inert landfill sites, rather
than Non-‐Hazardous
landfills, this achieving cost savings.
