The contractor set the goal to achieve a shear strength of at least 100 kPa. This target is achieved only with binders containing ≥70% GGBS. Pure OPC treatment does not develop sufficient strength over time.
The inclusion of high volumes of GGBS in the binder enables a significant lowering of the heavy metals leaching with time. Even compared to the untreated sediments, the addition of pure OPC has the tendency to increase heavy metals leaching whereas GGBS-rich binders tend to stabilize that property.
The contractor selected Ecocem blended cement containing 70% GGBS to realise the dredged sediments-based port extension in Howth.
In terms of heavy metals contamination, the EPA required particular attention to be given to three elements: Copper, Nickel and Zinc.
