Corrosion of 1050, 1085, and 5083 grade aluminium in the pore water of a GGBS/CEM I grout up to 777 d

Abstract Aluminium forms a significant part of a nuclear waste stream that will be encapsulated in CEM I (Portland cement)/GGBS (ground granulated blast furnace slag) grout. The aluminium is in the form of irradiated fuel cladding or containers used for transporting waste. The rapid rate of corrosion of aluminium in the cement pore water and the associated hydrogen generation during the initial curing of cement systems is well known. Longer-term corrosion data however, are relatively sparse, hence this work investigates corrosion up to 777 d measured from the rate of hydrogen generation. After an initial rapid corrosion stage, it has been shown that the corrosion rate decreases in a predictable linear manner depending on the inverse of the depth corroded. Eventually the corrosion rate decreases to such a low value that the corrosion effectively ceases. When the corrosion that has taken place is compared with the voidage generated by the hydrogen generation whilst the grout is in the plastic state, then it is apparent that insufficent corrosion is likely to take place for the expansive corrosion product generated to fill these voids. Hence the formation of these corrosion products does not significantly affect the performance of the wasteform and container.