Description :
Thanks to their environmental acceptability and their adaptability over a wide range of applications, alkali solutions of aluminosilicates are increasingly used. During the last 10 years, they have indeed increased their important role as inorganic and water based binders, notably for the production of mineral based, ecological materials for the building and construction industry. Especially during the last decade alkali-silicate solutions became more and more important for the alkali activation in geopolymer application, which is considered as “green chemistry”. Another important application is the use of sodium aluminosilicate gel for the so called “ground stabilisation” and as “sealing layers” in order to avoid the inflow of groundwater in construction pits or the reinforcement of sandy ground. Although such solutions are increasingly used in the industry, there remain outstanding questions regarding their stabilities, and more precisely concerning the gelation process that is driven by the composition of the solution. It is therefore crucial to provide a clear and realistic description of such fluids during the gelation process, which remains quite not well known, and has to be confirmed experimentally and theoretically.

The aim of this work is to describe the gelation process according to the chemical composition of the solution (alkali silicates and aluminates). The influence of the nature of alkali (Li, Na, K, Cs), of the aluminate and water content on the sol/gel transition will be assessed by using multiscale techniques. First, rheological parameters such as elasticity, viscous dissipation, yield stress will be measured to have a macroscopic vision of the material. In order to give an insight of the spatio-temporal phenomena, scattering techniques will be used and especially SAXS and SANS to get information about the structure evolution of the aluminosilicates oligomers during the gelation process. The use of a new laboratory Rheo-SAXS device is also considered. Finally, Raman spectroscopy which is known to be a powerful technique to determine the nature of the chemical link will be used to characterize the evolution of the aluminosilicate speciation during the sol/gel transition.

The project is a collaborative work between scientists from l’Institut de Chimie Séparative de Marcoule (ICSM) : M. Duvail and O. Diat and the laboratory Charles Coulomb in Montpellier : D. Petit. The proposed research team gathers experts from (i) molecular dynamics simulation, (ii) physics and soft materials, with recognized skills in the fields of Small Angle Scattering techniques and NMR multiscale characterization.

The present offer is a 2 years post-doc fellowship. The successful applicant will be mainly located at the Physical Chemistry of Waste Cementation Laboratory in CEA of Marcoule and will also have to spend time in the other aforementioned labs.

We are looking for a candidate with good expertise in sol/gel process, rheology and scattering techniques (X-ray and Neutron). An experience on synchrotron facilities will be appreciate.

Application procedure :

Applicants should provide a motivation letter, a CV including a complete list of publications, conferences and names with e-mail addresses of at least two references. All documents should be sent as pdf files via e-mail to Dr. A. Poulesquen (arnaud.poulesquen@cea.fr) and Dr. J.B. Champenois (jeanbaptiste.champenois@cea.fr).

Reference :

Date de démarrage : 01 janvier 2017

Durée : 2 ans

Contacter :
CEA Marcoule
Poulesquen Arnaud
BP 17171, 30207 Bagnols sur Cèze
email : arnaud.poulesquen@cea.fr
Téléphone : 0466791801