01929nas a2200337 4500008004100000022001400041245007900055210006900134260000800203300000700211490000700218520093900225653002801164653001201192653001601204653001301220653002001233100001901253700002301272700001901295700001701314700001801331700001701349700001601366700001701382700002101399700001901420700002301439700001601462856011301478 2026 eng d a0250-470700aFly-ash-based geopolymers: leachability and solid-state NMR investigations0 aFlyashbased geopolymers leachability and solidstate NMR investig cMAR a540 v493 a

This study aims to explore how leaching impacts the microstructure of a selected fly ash-derived geopolymer and evaluate its potential for near-surface disposal of radioactive waste. The uniqueness of this geopolymer formulation is its ability to form an aluminosilicate network that remains resistant to structural changes upon contact with water. The leach index of base elements such as Ca, Al, Na and Si was between 11 and 13, suggesting that the formulation is superior to Portland cement or conventional hydraulic cement. Solid-state NMR reveals that the water-interacted specimen has no contamination of the zeolite phase and all the Na is incorporated into the aluminosilicate geopolymer gel network, which also confirms that the glassy network of the geopolymer is responsible for imparting low leachability of base elements from its structure, and there is no labile sodium available for exchange as in zeolites.

10aaluminosilicate network10aFly ash10aGeopolymers10aleaching10aSolid-state NMR1 aNadol, Athulya1 aAjithkumar, T., G.1 aSingla, Rashmi1 aAlex, T., C.1 aKumar, Sanjay1 aBhatt, Himal1 aDeo, M., N.1 aSen, Debasis1 aAmbashta, R., D.1 aBajpai, R., K.1 aShivakumar, Y., C.1 aManohar, S. uhttps://library.ncl.res.in/content/fly-ash-based-geopolymers-leachability-and-solid-state-nmr-investigations