Modelling glass alteration in an altered argillaceous environment

RTM for Waste Repositories

“…Equation 1also highlights the fact that a porosity has to be defined for the considered materials. However, some of them (e.g., steel and other metals, glass) are not porous materials, and, unfortunately, reactive transport models are, by definition and according to Equation 1, not suited to include non-porous media (Bildstein et al 2007;Claret et al 2018b). To unravel this problem, the volume clearance that exists at the interface between the canister or the glass and the surrounding material, also known as the "technological gap", is often included in the numerical cells that represent these materials.…”

“…Numerical studies of glass alteration at the space scale of the disposal cell (50 m) and the corresponding time scale (100,000 years) are scarce (Bildstein et al 2007(Bildstein et al , 2012. In these simulations, glass alteration follows a very simple "operational" model in which the alteration proceeds in two stages, after a time lag corresponding to the time before canister failure (700 years): a first initial phase where the alteration rate (r 0 ) is high and a second stage where a residual, much lower, rate has been established (~r 0 /10,000).…”

“…The most noticeable evolution in the RTM approach to glass alteration in these two studies concerns the complexity of the geochemical and mineral system. Bildstein et al (2007) took into account only four simple mineral phases as glass alteration products, including one zeolite. The second paper (Bildstein et al 2012) includes 26 secondary minerals, with 14 glass alteration products, some of them determined from experimental studies (including Fe-silicates and Fe-aluminosilicates)( Figure 3).…”

Mapping the archaeological soil archive of sand and gravel mineral reserves in Britain

“…The crystallization of salts can lead to physical degradation of bone and other porous archaeological materials, including stone, ceramics, and plaster (Caple, 2004;BRE, 2005). The dissolution rate of silicate glasses will also increase in the presence of certain alkali and alkaline earth salts (Ca 2ϩ , Na ϩ , K ϩ , but not Mg 2ϩ ) (Silvestri, Molin, & Salviulo, 2005) and also at high pH (up to 5 times greater at pH 9 than at pH 7) (Bildstein et al, 2007).…”

“…Characterization of the soil archive is particularly useful when combined with short-(e.g., Meeusen et al, 1997;Burroni et al, 2002;Jans et al, 2002;Bergstrand et al, 2005 Van Heeringen & Theunissen, 2006) and long-term (e.g., Bell, Fowler, & Hillson, 1996;Matthieson et al, 2002;Caple, 2004) monitoring studies of in situ archaeological relics and other remains, such as nuclear waste storage in geologic repositories (e.g., Jantzen, 1992;Ben Lagha et al, 2007;Bildstein et al, 2007), to provide valuable information linking environmental parameters and archaeological degradation. The condition of artifact remains themselves may provide some indication of the soil history as well as the current status of a site.…”