MICROSTRUCTURE EFFECTS ON THE HYDRATION AND WATER TRANSPORT IN COMPACTED BENTONITES USED FOR RADIACTIVE WASTE DISPOSAL
Engineered barriers made up of bricks of heavily compacted swelling clays are considered as a possible option to isolate high activity radioactive wastes at great depth (from 200 to 500m). Satisfactory isolation is ensured by the low permeability that is typical of heavily compacted smectites and by the fact that, being confined in between the waste canister and the host rock, compacted bentonites cannot swell when hydrated, resulting in the closure of all existing gaps. The paper presents a detailed analysis of the microstructure changes that occur in compacted bentonites when submitted to infiltration. It shows how the fundamental mechanisms evidenced by advanced microstructure and mineralogical investigations at a nano scale have some direct applications at the macroscopic level. Both water retention properties and unsaturated permeability are affected by the clogging of the inter-aggregate pores that exist in the initial compacted state.Practical conclusions in terms of modelling the in-situ infiltration of the engineered barriers are also drawn.
Pierre Delage Yu Jun Cui
Ecole Nationale des Ponts et Chaussées (CERMES, Institut Navier), Paris, France
国际会议
南京
英文
85-96
2007-04-21（万方平台首次上网日期，不代表论文的发表时间）