Glass - Back to the Future!



Presenting Author:
Rawan El Hayek
<rawan.elhayek@lafargeholcim.com>

article posted 23 March 2016


Rawan El Hayek is a second year PhD student at LafargeHolcim research center in Lyon, France in collaboration with “Institut de Physique du Globe de Paris”. She has graduated with a master degree in “Inorganic chemistry” at Claude Bernard university Lyon 1. Actually her research interests focus on the characterisation of the amorphous phase present in a belite sulfoaluminate clinker in order to control its formation during the industrial production. Therefore she has been working on aluminoborate glasses to understand their structure and their influence on macroscopic parameters such as viscosity, Tg, etc. Recently she has participated to the 10th Silicate Melt Workshop at “la petite Pierre – Alsace, France”. She has already worked on other types of concretes and has dedicated her master’s thesis to concrete curing with CO2.






The influence of Al,B substitution on the properties and structure of lime aluminoborate glasses and melts

Rawan El Hayeka,b*, Frédérique Fereyb, Pierre Florianc, Alexander Pischa et Daniel R. Neuvilleb
a Lafarge Centre de Recherche, 95 Rue de Montmurier, 38070 Saint Quentin Fallavier, France


The calcium aluminate compositions are the base of the CaO–Al2O3–SiO2 system which is very important for geological and industrial concerns. These compositions are also interesting for a fundamental structural point of view because of the lack of any other network former than Al2O3. The aim of our study is to investigate the substitution of aluminum by boron. In this case a competition between two network formers can be observed. It has been proved that aluminum can be in 4, 5 and 6 fold coordination in calcium aluminosilicate glasses (Neuville et al, 2006) whereas boron can be in 3 and 4 fold coordination in borosilicate glasses (Martens et al, 2000). In order to understand what happens when replacing aluminum by boron, different glasses were made starting with Ca-aluminate glass, “C12A7”, and then progressively adding boron until the complete substitution of Al. Raman, 11B NMR and 27Al NMR were used to investigate the structure of these glasses at medium and short range order. Density, DSC and viscosity measurements were also done in order to realize what is going on a macroscopic scale. NMR and Raman spectra show that aluminum in Ca-aluminate glass is in Al[4],more precisely in Q3 and Q4 species according to (Neuville et al, 2010). Whereas, when boron replaces aluminum, BO3 is mainly formed in good agreement with the two spectroscopic methods. An important drop of Tg is observed when BO3 units appear. As the concentration of boron increases, NBOs are formed to create tetrahedral boron, BO4. Tg continues to decrease but with a slower rate. In this study, we will present all these results and discuss the influence of the network’s structure on the macroscopic parameters.

References
Neuville, D. R., Cormier, L. & Massiot, D. Al coordination and speciation in calcium aluminosilicate glasses: Effects of composition determined by 27Al MQ-MAS NMR and Raman spectroscopy. Chem. Geol. 229, 173–185 (2006).
Martens, R. & Müller-Warmuth, W. Structural groups and their mixing in borosilicate glasses of various compositions - an NMR study. J. Non. Cryst. Solids 265, 167–175 (2000).
Neuville, D.R. et al., 2010. The structure of crystals, glasses, and melts along the CaO-Al2O3 join: Results from Raman, Al L- and K-edge X-ray absorption, and 27Al NMR spectroscopy. American Mineralogist, 95(10), pp.1580–1589.




Figure 1: Unpolarized Raman spectra of lime aluminoborate glasses



Figure 2: Density values for glasses along the join CAB37.00-CAB00.37


b IPGP-CNRS, Géomatériaux, Paris Sorbonne Cité, 1 rue Jussieu, 75005 Paris, France
c CEMHTI – CNRS, rue de Ferrolerie, 45000 Orléans, France