ABSTRACT
Zeolites are used to remove radioactive cations from contaminated waters. The contaminated zeolites must themselves be conditioned before they can be disposed of in a near-surface repository. Portland cement is commonly used to immobilise radioactive wastes. However portlandite (calcium hydroxide), formed in hydrating cement, reacts with many zeolites to form calcium silicate hydrate. This pozzolanic reaction destroys the zeolite, freeing mobile cations such as caesium [1] [2].
