The Couplings of Rock/Carbonate Groundwater/Cement Leachate

Hyper-alkaline cement leachates generated from the cement buffer of a nuclear waste disposal site have significant influences on the mineralogy of the host rock, creating a chemically disturbed zone (CDZ). Three major types of cement leachates are formed during the evolution process. Most of the existing scenario modelling research has been focused on the influence of the cement leachate on the host rock. However, the influence of the groundwater in the host rock on the evolution of the CDZ remains unexplored. This paper presents a numerical scenario modelling of the couplings among carbonate groundwater, cement leachates and rock minerals. The results reveal that the high carbonate groundwater significantly affects the precipitation of calcium silicate hydrate (C-S-H) and calcite, and consequently alters the physical and chemical properties of the host rock. This finding provides an essential guide for selection of the location of geological disposal facility (GDF) in terms of the groundwater chemistry.