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Fig. 1 | Heritage Science

Fig. 1

From: Recent progress in instrumental techniques for architectural heritage materials

Fig. 1

TL and PL-OM photographs of the calcarenites reacted with high concentration of salt solutions and thenardite crystals. a carbonate cement dissolved in MgSO4·7H2O and CaSO4·2H2O aqueous solution; b the surface of calcarenite was split after the action of Mg-rich salts; c K2SO4 simple solution had no effect on the surface topography of calcarenites; d after reaction with NaSO4·10H2O aqueous solution, the thenardite crystals displayed non-equilibrium needle shapes; e the acicular shape (phase III) of thenardite crystals is easy to generate under conditions of 20 °C and RH > 40%; f massive amounts of bipyramidal prisms crystals (phase V) formed at 20 °C and 13% RH [51, 52], copyright (2000, 2008) Elsevier

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