Processing and product characteristics of a blended cement grout incorporating polycarboxylate ether superplasticiser

Abstract

Superplasticisers improve the flow properties of cement and offer a number of operational advantages to producers of radioactive waste. Research is underway to clarify their mode of interaction using a bespoke, purified polycarboxylate ether (PCE) superplasticiser in controlled trials. A large-scale (200 dm3) product was prepared with a mix of ground granulated blast-furnace slag and ordinary Portland cement (9:1 mix) and tested using methods established by the UK nuclear industry to assess grout performance. The product met the essential criteria for a radioactive waste encapsulation grout. Laboratory-scale studies utilising a 14C-labelled superplasticiser and its components were employed to better understand the mechanisms involved and to determine the location and distribution of the superplasticiser within cured cement monoliths. The results suggest that a PCE superplasticiser may enable the use of cement industry standard powders for encapsulation processes, allowing lower water content matrices and mitigating the risk of future powder supply issues.