The Radiation Stability of Ground Granulated Blast Furnace Slag/Ordinary Portland Cement Grouts Containing Organic Admix
- PDF / 298,488 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 72 Downloads / 173 Views
THE RADIATION STABILITY OF GROUND GRANULATED BLAST FURNACE SLAG/ORDINARY PORTLAND CEMENT GROUTS
CONTAINING ORGANIC ADMIXTURES JOHN D PALMER AND GRAHAM A FAIRHALL British Nuclear Fuels plc, Sellafield, Seascale, Cumbria, UK ABSTRACT At the British Nuclear Fuels (BNFL) Sellafield reprocessing plant in the United Kingdom, cement grouts based on ground granulated blast-furnace slag (BFS) and ordinary Portland cement (OPC) are used extensively for immobilising radioactive wastes. These grouts have excluded organic admixtures in order to reduce process complexity and uncertainties, regarding the performance of organic admixtures *with BFS/OPC grouts, particularly under irradiation. This study has investigated the effects of sulfonated melamine The results formaldehyde and naphthalene condensates on grout properties. show grout settlement and strengths increase on addition of additives, with the additives remaining largely in the pore solution. Under irradiation the Strength and additives breakdown liberating hydrogen and carbon dioxide. product dimensions are unaffected by irradiation. INTRODUCTION Organic admixtures are used extensively in the cement and construction industries to modify the properties of grouts and concretes. The advantages of using admixtures can include improved grout fluidity, making placement easier; alterations in setting times to compensate for seasonal temperature variations; or improved durability to freeze/thaw cycling. These properties can also be of benefit in the nuclear industry where cement grouts are used to immobilise radioactive waste. Over the past 10 years BNFL has developed a range of cement grouts for immobilising the 23 major wastestreams generated during fuel reprocessing operations at the Sellafield site. These grouts have been based extensively and ordinary on blends of ground granulated blast-furnace slag (BFS) Portland cement (OPC) which have been shown to satisfy process and product requirements. The majority of grout formulations developed by BNFL have excluded admixtures in order to reduce process complexity and eliminate potential interactions between the organic components or their degradation products and the waste or the encapsulation matrix. To achieve the necessary process control without admixtures, a tight physical and chemical specification has been applied to the cement materials used in BNFL's encapsulation plants. However, for certain waste types that are too large or too heavy to be vibrated, grouts using plasticising agents have been developed to assist have included operations. The admixtures investigated infilling super-plasticisers based on sulfonated melamine formaldehydes and sulfonated naphthalene formaldehydes. This report considers this effects of the above admixtures of rheology, In addition, setting, strength and pore solution chemistry of the grouts. the gamma radiation stability of grouts containing these admixtures has been assessed at cumulative doses of upto 9MGy.
Mat. Res. Soc. Symp. Proc. Vol. 294. ©1993 Materials Research Society
286
SC
Data Loading...
