Dissolution Kinetics of International Simple Glass and Formation of Secondary Phases at Very High Surface Area to Solution Ratio in Young Cement Water

Abstract

Static dissolution experiments were carried out with the reference International Simple Glass under hyperalkaline pH at 70 °C and very high SA/V ratio. Three aspects of glass dissolution behavior were investigated, (1) the rate drop regime and the residual rate (stage II), (2) the formation of secondary phases including thermodynamic aspects, and (3) the microstructure of the interface of altered glass and secondary phases. A very low residual rate of 6 × 10−6 g/m2d was determined based on boron release, which was several orders of magnitude lower than the initial rate established between the start of the experiments and the first sampling on day 59. The presence of a porous layer with a thickness varying between 80 nm and 250 nm and a pore size between 10 nm and 50 nm was observed. CSH phases with a low Ca/Si ratio of 0.3–0.4 and zeolites were also visible at the surface of the altered glass grains, but no glass alteration resumption occurred, probably due to an important pH decrease already at day 59. Thermodynamic calculations assuming congruent glass dissolution and precipitation of the dissolved aqueous species confirmed the precipitation of CSH phases and zeolites.

Effects of Al:Si and (Al+Na):Si ratios on the static corrosion of sodium‐boroaluminosilicate glasses

“…The CJ4 composition was chosen for fabrication as the International Simple Glass (ISG) by the international nuclear waste glass community to study glass properties and durability behavior. 1,[55][56][57][58][59][60][61][62][63][64][65] A new series covering an extended Al compositional space based on the composition of ISG would provide valuable information regarding the effect of Al on long-term durability applicable to nuclear waste glasses.…”

Caesium and iodine release from spent mixed oxide fuels under repository relevant conditions: Initial leaching results

“…The YCW has a pH of 13.5 and contains K, Na, and Ca, as well as traces of Si, Al and B, with contents comparable to those reported by Ref. [9]. In order to investigate the influence of the leachate on the dissolution behaviour, the high burnup segments (DIS1 and DIS2) are leached in YCW and BIC, respectively.…”

Titanium in GGBS-like calcium-magnesium-aluminosilicate glasses: Its role in the glass network, dissolution at alkaline pH and surface layer formation

“…In the literature, reduction of glass dissolution rates due to surface layer formation is commonly observed. 65,75,76 In a cement setting with concurrent dissolution and precipitation, the Ti surface layer might become passivating. The experiments at pH 13 suggest that Mg-aluminates, such as hydrotalcite, might precipitate in the pores.…”