(2020) The Effect of Ti and Other Minor Elements on the Reactivity of Granulated Ground Blast Furnace Slag (GGBS) in Blended Cements
Blotevogel S, Steger L, Bornhöft H, Deubner J, Doussang L, Fayon F, Hart D, Kaknics J, Montouillout V, Patapy C, Saldi G, Schott J & Cyr M
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08r: Plenary Hall, Friday 26th June 06:48 - 06:51
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Is it possible that the addition of TiO2 promote the formation of short- to mid-range ordered structure in the glass matrix? Did ZrO2 and Cr2O3 show a similar effect in decreasing the compressive strength of the slag glass?
Dear Fulvio, thank you for your question. We did not perform compressive strength tests on glasses, but on the mortars issued from the cemetitious reaction of the glasses - I hope that was clear in the talk. For ZrO2 and Cr2O3 we did not do compressive strength tests but used reaction heat as a proxy. And yes there were similar effects as for TiO2. All glasses were still XRD amorphous (Cu anitcathode). However, the point I wanted to make is that if the effect comes from changes in the glass network you would expect changes in initial dissolution rate. But we did not observe those. Our hypothesis for the moment is that those insoluble elements form or impermeabilize a gel layer during the reaction, similar to those observed in nuclear waste glass dissolution. This could slow down the overall reaction. If you have ideas on that, I am happy to exchange.
Dear Simon, thanks for the clarifications. you mentioned that the lack of Ti in solution after the glass dissolution is mainly due to the accumulation at the surface. This accumulation should produce a reduction of the reactive surface area of the glass, thus decreasing the dissolution rate. However, the amount of TiO2 showed no effect on the dissolution rate of the glass. Is TiO2 forming something like a permeable layer? or at least as permeable as the layer that forms in absence of TiO2? Have you made any high resolution microscopy of the dissolution products?
Yes we suppose it does form a more or less permeable layer. The microscopy is work in progess... but we do not have results yet.
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