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One possible disposal route for the long-term management of Belgian reactor 1 (BR1) fuels, which will eventually become nuclear waste, is geological disposal. In this disposal, Aluminium-1100, as the outermost material of BR1 fuel, will contact with a cementitious matrix directly. Due to its amphoteric property, aluminium cannot form a passive corrosion product film in Ordinary Portland Cement (OPC) paste, which possesses a highly alkaline condition. Without the protection of a passive corrosion product film, the corrosion process can proceed rapidly and threaten the encapsulation safety. One potential solution for this problem is the application of lithium salts in OPC paste. Lithium ion is believed to be capable of intercalating into aluminium hydroxides to form a layered double hydroxide in high pH conditions [1], [2]. Some literature reported the excellent inhibiting ability of LiNO3 and Li2CO3 for the corrosion of aluminium in high pH conditions [3]-[6]. The corrosion of aluminium in three types of cement pastes was studied. They are 0.36 w/c OPC+3 wt% LiNO3, 0.50 w/c OPC+1.607 wt% Li2CO3 and 0.36w/c OPC. For each type of cement paste, two curing conditions were adopted. In Condition 1, samples were placed in humid Ar atmosphere and then transferred to saturated Ca(OH)2 solution after the corrosion rates reached the steady state (after about 80 days in this study). This transferring is to stimulate the intrusion of underground water in a real geological disposal repository. In Condition 2, samples were immersed in saturated Ca(OH)2 solution from the beginning of the test. Electrochemical Impedance Spectroscopy (EIS) was applied to study the corrosion product film and the variation of the corrosion rate of aluminium in these cement pastes. Its results were examined by other techniques, i.e. SEM and GC. Moreover, by the innovative combination of the equivalent circuit model and the General Effective Media theory, EIS is capable of providing the porosity information of cement pastes. Mercury Intrusion Porosimetry (MIP) showed the reliability of the porosity results obtained from EIS. Following conclusions can be obtained from this research: (1) Both LiNO3 and Li2CO3 are effectively corrosion inhibitors for Al in OPC paste. However, it is difficult to compare their inhibition abilities directly from the results because 0.50 OPC+1.607% samples have a higher water/cement ratio for a better workability; (2) The immersion of samples in saturated Ca(OH)2 solution will increase the corrosion rate; (3) For 0.50 OPC+1.607% samples, when the thickness of the corrosion product film grows up to ~10 µm, a delamination is highly likely to occur. [1] Williams et al., The Journal of Physical Chemistry B, 110(22), 10619-10629. [2] Buchheit et al., Corrosion, 50(3), 205-214. [3] Delpech et al., Journal of The Electrochemical Society, 164(13), C717. [4] Nicu et al., Phys, 60(7-8), 1193-1202. [5] Visser et al., Journal of The Electrochemical Society, 165(2), C60. [6] Visser et al., Faraday Discussions, 180, 511-526.

La simulation thermodynamique commence à s’utiliser dans le domaine des matériaux cimentaires. Cet outil thermodynamique est actuellement employé principalement comme moyen de vérification où d’interpolation de résultats pour des mélanges dont la composition chimique est connue de façon précise. Cependant, les avancées de cette technologie nous laissent penser qu’il est possible de l’utiliser comme outils de conception ou de préformulation permettant d’affiner et d’optimiser les matériaux cimentaires. Nous avons donc tenté à l’aide de la seule composition chimique et du taux d’hydratation de nos matériaux de simuler quatre mélanges cimentaires à base de ciment Portland, de laitier de haut fourneau et de filler calcaire. Nous avons, ensuite comparé les résultats ainsi obtenus à ceux obtenus par l’analyse DRX. Ainsi nous avons constaté que la plupart des mécanismes d’hydratation qui ont lieu dans ces mélanges ont été prédits par le calcul thermodynamique. Néanmoins, les proportions calculées par la simulation ne sont pas toutes en concordance avec ceux obtenus par les résultats DRX., Academic Journal of Civil Engineering, Vol 34 No 1 (2016): Special Issue - RUGC 2016 Liège