The engineering of a cementitious barrier

When cementitious materials are used for the containment of waste they act in two different and sometimes conflicting ways. The first is physical containment in which the waste is physically isolated from the environment. The second is chemical containment in which the water passing through the barrier is buffered to high pH thereby very substantially reducing the solubility of many harmful species and promoting sorption onto the cement matrix. Chemical barriers have been extensively researched for nuclear waste containment and this paper explores the possibility of using them for non-nuclear waste. Initial results are presented which show that cementitious barriers containing cement replacement materials may be well suited to barrier construction. It is, however, concluded that cementitious barriers would have to be used as part of a composite system in order to comply with current legislation.