Published online by Cambridge University Press: 25 February 2011
The R7T7 and synthetic basaltic glasses were submitted to corrosion in a saline MgCl2 dominated solution at 190°C. For both glasses, the early alteration product is a hydrotalcite-like compound in which HPO42-, SO4-2 and Cl- substitutes to CO32. The measured d003 spacing is 7.68 Å for the hydrotalcite formed from R7T7 glass and 7.62 Å for the hydrotalcite formed from basaltic glass which reflect the high aluminium content. Chemical microanalyses show that the hydrotalcite is subsequently covered by a silica-rich gel which evolves into saponite after few months.