Accueil >
Production scientifique
Matériaux hybrides et nanostructurés
(2) Production(s) de l'année 2023
|
|
THE PERMEABILITY OF SILICA AEROGELS 
Auteur(s): Woignier Thierry, Anez Liz, Primera Juan, Etienne P., Phalippou Jean
Chapître d'ouvrage: Handboook Of Aerogels, vol. p. (2023)
Ref HAL: hal-04282095_v1
DOI: 10.1007/978-3-030-27322-4_10
Exporter : BibTex | endNote
Résumé: Silica aerogels have many potential applications, including as host matrices for chemical species or nuclear waste storage. For these applications, the permeability is a key parameter and data show that the silica aerogels have poor permeability (~10-60 nm 2). In this chapter we review the method to measure the liquid and gas permeability in gels, aerogels and composite aerogels. Ideally, permeability does not depend on the type of pore fluid, therefore permeability measured using gas should be the same as that measured using water. We measured gas and water permeability in sets of nano composite silica aerogels. Experimental results show that gas permeability in aerogels was larger than water permeability by almost two orders of magnitude. The observed difference in gas and water permeability was analyzed from the point of view of the slip regime (Klinkenberg correction), and transition regime (Knudsen correction), the slip flow of gas at pore walls enhance the gas flow when pore sizes are small. This work addresses the problem of estimating permeability with high porosity materials such as aerogels. The effects of structural parameters of porous media (pore volume, tortuosity, fractal features) on the Klinkenberg and Knudsen corrections are discussed and the different models proposed in the literature are tested.
|
|
|
|
Mechanical tensile behaviour of cement paste/aggregate bond exposed to leaching
Auteur(s): Gîrboveanu Andrei, Jebli Mouad, Jamin Frédéric, Huon Vincent, Bonnet L., Georgescu Dan, El Youssoufi Moulay Saïd
(Article) Publié:
Construction And Building Materials, vol. 369 p.130592 (2023)
Ref HAL: hal-04071077_v1
DOI: 10.1016/j.conbuildmat.2023.130592
Exporter : BibTex | endNote
Résumé: An experimental program is oriented to the mechanical behaviour of the Interfacial Transition Zone (ITZ) exposed to leaching, for a single mix. Leaching kinetics of the degraded depth, measured through grey level on cross sections, reveals a maximum gap of 10 % between ITZ and bulk cement paste. ITZ, with a main thickness of 15 µm suffers a significant decalcification, which is reflected on the mechanical properties of the bond. Grey level, Calcium/Silicon (Ca/Si) molar ratio and Young’s modulus in the degraded zone present similar evolution. Effect of ITZ causing cracking and then debonding is noticed, through chemical analysis, image observation and mechanical tests.
|
