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Deneele, Dimitri

Justino, Christophe

Loukili, Ahmed

Paris, Michaël

Rozière, Emmanuel

Souayfan, Faten

English

Engineering Conferences International

EXPLORATION OF THE PHASE COMPOSITION OF ACTIVATED CALCINED CLAY-SLAG MIXTURES USING 27Al and 29Si MAS NMR SPECTROSCOPY  Faten Souayfan, Ecole Centrale de Nantes  Faten.souayfan@ec-nantes.fr Emmanuel Rozière, Ecole Centrale de Nantes Michaël Paris, Université de Nantes Dimitri Deneele, Univ Gustave Eiffel Ahmed Loukili, Ecole Centrale de Nantes Christophe Justino, Soletanche Bachy   Key Words: Alkali-activated materials, Slag, Calcined clay, 29Si MAS NMR, 27Al MAS NMR  Alkali-activated materials (AAM) are considered as a next-generation material to replace Portland cement materials for durability purposes in some severe conditions. AAM using blended binders have been developed to compensate for limitation related to precursors and activating solutions. However, there are disperse opinions describing the phase composition of a hybrid system related to the variety of chemical compositions [1] [2] [3]. In this work, the phase composition of a hybrid calcined clay-slag material activated by sodium silicate is studied with a special emphasis on the effect of H2O/Na2O ratio. Different approaches based on literature were analysed to identify the formed phases using 29Si and 27Al Nuclear magnetic resonance spectroscopy. Three decomposition methods were applied to the same 29Si spectra (Figure 1). A conceptual model of the process was proposed. A heterogeneous phase involved in the transformation of the 3D network to C-A-S-H is formed. The presence of local structures at high and low frequencies, which are linked by q4 Al species confirmed this model. Additionally, the issues related to the deconvolution method were highlighted.         [1] A. Aboulayt, F.Souayfan,.E.Rozière, R.Jaafri, A.C. El Idrissi, R. Moussa et A. Loukili « Alkali-activated grouts based on slag-fly ash mixtures: From early-age characterization to long-term phase composition », Construction and Building Materials, vol. 260, p. 120510, nov. 2020, doi: 10.1016/j.conbuildmat.2020.120510. [2] P. Perez-Cortes et J. I. Escalante-Garcia, « Gel composition and molecular structure of alkali-activated metakaolin-limestone cements », Cement and Concrete Research, p. 13, 2020, doi: 10.1016/j.cemconres.2020.106211. [3] I. Garcia-Lodeiro, A. Palomo, A. Fernández-Jiménez, et D. E. Macphee, « Compatibility studies between N-A-S-H and C-A-S-H gels. Study in the ternary diagram Na2O–CaO–Al2O3–SiO2–H2O », Cement and Concrete Research, vol. 41, no 9, p. 923-931, sept. 2011, doi: 10.1016/j.cemconres.2011.05.006.    Figure 1–Decompositions of 29Si spectrum of activated calcined clay-slag mixture based on different approaches   

Exploration of the phase composition of activated calcined clay-slag mixtures using 27Al and 29Si MAS NMR spectroscopy

https://dc.engconfintl.org/cgi/viewcontent.cgi?filename=0&article=1003&context=geopolymers2023&type=additional

Exploration of the phase composition of activated calcined clay-slag mixtures using 27Al and 29Si MAS NMR spectroscopy

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Engineering Conferences International