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Aktualności i Wydarzenia

Central and Eastern European Conference on Thermal Analysis and Calorimetry w Kiszyniowie

30-08-2017

Streszczenie wygłoszonego referatu "Natural and artificial pozzolans saline hydration for their reactive alumina qualitative and quantitative assessment, by TGA":

"Reactive alumina, Al2O3r-, is a constituent of natural and artificial pozzolans (thermally activated clays, natural pozzolans of volcanic origin, fly ash, diatomite, silica fume), used as mineral additions to Portland cement (PC) based materials due to environmental (1 t of conventional PC releases 1 t of CO2), technological (higher mechanical strength of the resultant PC blends) and economic reasons (energy savings) [1][2]. Performance of this hydraulic factor in building materials, if present, is related directly to the chemical durability against their exposure to chlorides and/or sulphates. Ergo, thaw salts and marine environments contribute to hindering and preventing electrochemical corrosion of steel reinforcement of reinforced concrete due to rapid forming Friedel's salt [3][4][5]. In return, gypsum-bearing water and/or soils promote degradation of concrete and mortar quality due to expansion, shrinkage and decomposition of PC hydration products caused by rapid forming ettringite [6][7].

Qualitative and quantitative assessment of the reactive alumina, Al2O3r-, content in pozzolans is addressed pioneeringly in this research as all the tetra– or penta–coordinated alumina [8][9] capable to react chemically in form of Friedel’s salt compound. Saline hydration natural and artificial pozzolans are here subjected to, is studied maximally up to 28 days-age using TGA (TG/DTG/DTA) techniques (TA Instruments). The resultant amorphous and/or vitreous Al2O3r- contents are contrasted with the Florentin reference method [10] up to 1 year-age, giving a satisfactory convergence between both data sets. Finally, the precision and repeatability of the newly proposed analytical method is validated conforming obligatory requirements of ISO/IEC 17025 standard for quality and reliability of new analytical trials [11], namely its standardization is resultatively recommended to be considered in a future."

References:

  1. P.K. Mehta, Concr. Int., 21 [11] 47-52 (1999).
  2. B. Uzal, L. Turanli, P.K. Mehta, ACI Mater. J., 104 (5) 535-538 (2007)
  3. R. Talero, L. Trusilewicz, A. Delgado, C. Pedrajas, R. Lannegrand, V. Rahhal, R. Mejía, S. Delvasto, F.A. Ramírez, Constr Build Mater., 25 [5] 2370−2380, (2011).
  4. R. Talero, L. Trusilewicz, Ind Eng Chem Res., 51 [38] 12517−12529 (2012).
  5. R. Talero, Constr Build Mater., 33, 164-180 (2012).
  6. R. Talero, Constr Build Mater., 24 [9] 1779-1789 (2010).
  7. R. Talero, Constr Build Mater., 25 [3] 1139-1158 (2011).
  8. L. Trusilewicz, F. Fernández-Martínez, V. Rahhal, R. Talero, J Amer Ceram Soc,. 95 (9) 2989-2996 (2012).
  9. L. Trusilewicz, Ph.D. Thesis, Technical University of Madrid, ETSIDI, Madrid, Spain (2014).
  10. R. Feret, Revue des Materiaux de Construction et de Travaux Publics, 281, 41-44 and 282, 85-92 (1933).
  11. International standard ISO/IEC 17025:2005.

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