Damage in porous media due to salt crystallization.

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.

[1]  M. Prat,et al.  Effect of Efflorescence Formation on Drying Kinetics of Porous Media , 2009 .

[2]  W. G. Marshall,et al.  In situ characterization of elusive salt hydrates. The crystal structures of the heptahydrate and octahydrate of sodium sulfate. , 2008, Journal of the American Chemical Society.

[3]  Michael Steiger,et al.  Crystallization of sodium sulfate phases in porous materials: The phase diagram Na2SO4–H2O and the generation of stress , 2008 .

[4]  Robert Černý,et al.  Water and salt transport and storage properties of Mšené sandstone , 2008 .

[5]  Salima Rafaï,et al.  Salt crystallization during evaporation: impact of interfacial properties. , 2008, Langmuir : the ACS journal of surfaces and colloids.

[6]  G. Scherer,et al.  Crystallization of sodium sulfate salts in limestone , 2008 .

[7]  Philippe Coussot,et al.  Some Applications of Magnetic Resonance Imaging in Fluid Mechanics: Complex Flows and Complex Fluids , 2008 .

[8]  Olivier Coussy,et al.  Deformation and stress from in-pore drying-induced crystallization of salt , 2006 .

[9]  Barbara Lubelli,et al.  The Effect of Environmental Conditions on Sodium Chloride Damage , 2006 .

[10]  Michael Steiger,et al.  Crystal growth in porous materials—I: The crystallization pressure of large crystals , 2005 .

[11]  J. Roux,et al.  Delayed fracture in porous media. , 2005, Physical review letters.

[12]  L. Pel,et al.  Experimental evidence of crystallization pressure inside porous media. , 2005, Physical review letters.

[13]  G. Scherer Stress from crystallization of salt , 2004 .

[14]  Robert J. Flatt,et al.  Crystallization damage by sodium sulfate , 2003 .

[15]  Robert J. Flatt,et al.  Salt damage in porous materials: how high supersaturations are generated , 2002 .

[16]  R. Wüst,et al.  Rock deterioration in the Royal Tomb of Seti I, Valley of the Kings, Luxor, Egypt , 2000 .

[17]  Eric Doehne,et al.  How does sodium sulfate crystallize? Implications for the decay and testing of building materials , 2000 .

[18]  C. Rodriguez-Navarro,et al.  Salt weathering: influence of evaporation rate, supersaturation and crystallization pattern , 1999 .

[19]  R. L. Pigford,et al.  Kinetics of phase transitions in the system sodium sulfate-water , 1984 .

[20]  Lisbeth M. Ottosen,et al.  Salt Weathering on Buildings and Stone Sculptures , 2008 .

[21]  R.P.J. van Hees,et al.  The effect of environmental conditions on sodium chloride damage: A step in the development of an effective weathering test , 2006 .

[22]  J. Ulrich,et al.  The growth and dissolution of sodium chloride in a fluidized bed crystallizer , 2002 .

[23]  Heather Viles,et al.  Salt Weathering Hazard , 1997 .

[24]  Brian S. Bruckno,et al.  Engineering Geology , 1916, Nature.