Damage in porous media due to salt crystallization

Noushine Shahidzadeh-Bonn, Julie Desarnaud, François Bertrand, Xavier Chateau, and Daniel Bonn

Phys. Rev. E 81, 066110 – Published 16 June 2010

Abstract

We investigate the origins of salt damage in sandstones for the two most common salts: sodium chloride and sulfate. The results show that the observed difference in damage between the two salts is directly related to the kinetics of crystallization and the interfacial properties of the salt solutions and crystals with respect to the stone. We show that, for sodium sulfate, the existence of hydrated and anhydrous crystals and specifically their dissolution and crystallization kinetics are responsible for the damage. Using magnetic resonance imaging and optical microscopy we show that when water imbibes sodium sulfate contaminated sandstones, followed by drying at room temperature, large damage occurs in regions where pores are fully filled with salts. After partial dissolution, anhydrous sodium sulfate salt present in these regions gives rise to a very rapid growth of the hydrated phase of sulfate in the form of clusters that form on or close to the remaining anhydrous microcrystals. The rapid growth of these clusters generates stresses in excess of the tensile strength of the stone leading to the damage. Sodium chloride only forms anhydrous crystals that consequently do not cause damage in the experiments.

Received 1 March 2010

DOI:https://doi.org/10.1103/PhysRevE.81.066110

Authors & Affiliations

Noushine Shahidzadeh-Bonn^1,2,*, Julie Desarnaud^1,2,†, François Bertrand^1,‡, Xavier Chateau^1,§, and Daniel Bonn^2,3,∥

¹Laboratoire Navier, UMR 8205, Université Paris-Est, 2 Allée Kepler, 77420 Champs-sur-Marne, France
²Van der Waals-Zeeman Instituut (WZI), Universiteit van Amsterdam, Valckenierstraat 65, 1018 XE Amsterdam, The Netherlands
³Laboratoire de Physique Statistique de l’ENS, UMR 8550, 24 rue Lhomond, 75231 Paris Cedex 05, France

^*Corresponding author. bonn@lcpc.fr
^†desarnaud@lcpc.fr
^‡bertrand@lcpc.fr
^§chateau@lcpc.fr
^∥bonn@lps.ens.fr

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Issue

Vol. 81, Iss. 6 — June 2010

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Images

Figure 1
(a) Prague (Mšené) sandstone sample $(2 \times 2 \times 4 {cm}^{3})$ ( $ϕ \sim 25 %$ and $d_{p} = 30 μ m$ ) before the experiments. (b) and (c) After 2 cycles of wetting and drying, imbibing with ${Na}_{2} {SO}_{4}$ and NaCl, respectively, in the first cycle and imbibition with pure water in the second cycle. (b) Severe damage (loss of material) in the presence of ${Na}_{2} {SO}_{4}$ . (c) Strong adhered efflorescence but no damage in the presence of NaCl. Experimental conditions: $T = 21 ° C$ , $RH = 45 \pm 5 %$ .Reuse & Permissions
Figure 2
(a) Comparison of MRI saturation profiles between the time instants just after imbibition and after 5 h of drying in C1 and C2. The sample is imbibed with a saturated sodium sulfate solution in the first cycle and with pure water in the second one. Squares are for C1; circles are for C2. (b) Water content of the stone obtained from the MRI measurements (open symbols) and the weight measurements (filled symbols) during cycle 2. The difference reveals the formation of hydrated crystals that are not visible as water in the MRI experiments.Reuse & Permissions
Figure 3
Microphotographs of the formation of hydrated crystals of sodium sulfate (mirabilite) in rectangular microcapillaries. (a) Slow growth of large crystals from solution in cycle 1. (b) After rewetting with pure water (cycle 2), the anhydrous sodium sulfate crystallites (thenardite) that are visible as the small grains in the center of the aggregate do not dissolve completely, and the hydrated crystals grow from there. The latter are visible as the facetted transparent crystals.Reuse & Permissions
Figure 4
Dynamics of crystallization growth: typical size of a mirabilite crystal forming during the first cycle as a function of time in a rectangular microcapillary. Inset (to the right): the much faster growth when the mirabilite crystals form in clusters as observed in Fig. 3b.Reuse & Permissions
Figure 5
(Color online) Drop evaporation and rewetting experiments: top images are for NaCl whereas bottom images are for ${Na}_{2} {SO}_{4}$ . In both series, (a) corresponds to the salt deposit after drop $(20 μ l)$ of a saturated salt solution has dried. (b) corresponds to the rewetting with the same amount of water as was initially present in the drop under (a). In most cases, an only partial dissolution of the salt is observed, as the droplet evaporates at the same time. (c) shows the deposit after drying a second time. For NaCl a pattern similar to that under (a) is observed. However, the sulfate spreads out tremendously after rewetting, leaving a much larger area covered after drying.Reuse & Permissions

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