Short- and Longer-Term Consolidation Effects of Portlandite (CaOH)2 Nanoparticles in Carbonate Stones

The consolidation effects of portlandite (CaOH)(2) nanoparticles have been determined in carbonate stones (dolostone), typically used in historical buildings from Madrid, Spain, just after 20days consolidation at 20 degrees C under a dry [33% relative humidity (RH)] and a humid environment (75% RH) and after 18months under room temperature and humidity conditions (20 degrees C +/- 5 and 50 +/- 10% RH). The improvement of the physical and hydric properties, from short to longer term, of this dolostone is shown through the combination of nondestructive techniques (environmental scanning electron microscopy, spectrophotometry, water absorption under vacuum and capillarity, ultrasonic velocity, and optical surface roughness analyses) together with destructive techniques (mercury intrusion porosimetry and microdriling resistance measurement) also necessary for a better accuracy determination of pore structure and resistance modifications. Consolidation process under both humid and dry environment gives rise to an improvement of the petrophysical properties of dolostone specimens. However, a humid environment and a higher and larger porosity of the stone favor the consolidation with time, being these conditions are necessary to take into account when Ca(OH)(2) nanoparticles are used to consolidate carbonate stones.