A consolidating product based on nanoparticles of slaked lime (Ca(OH)2) dispersed in isopropyl alcohol was exposed under different relative humidities (RH), 33%, 54%, 75% and 90% during 7, 14, 21 and 28days. The characterization of the calcium hydroxide nanoparticles and the formed calcium carbonate polymorphs have been performed by Micro Raman spectroscopy, Transmission Electron Microscopy (TEM), Environmental Scanning Electron Microscopy (ESEM) with Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD). Precipitation and transformation of calcium carbonate polymorphs strongly depend on the relative humidity (RH). Higher RH (75%-90% RH) gives rise to amorphous calcium carbonate and monohydrocalcite, calcite, aragonite and vaterite, faster carbonation and larger particles sizes with higher crystallinity compared to lower RH (33%-54% RH) that gives rise mainly to portlandite and vaterite, slower carbonation and smaller particle sizes with lower crystallinity.
Bibliographical noteFunding Information:
This study was funded by the Government of the Community of Madrid by GEOMATERIALES ( S2009/MAT-1629 ) and CONSOLIDERTCP ( CSD2007-0058 ) and to the JAE-Doc CSIC contracts for supporting P. López-Arce and L.S. Gómez-Villalba to develop this work. We thank C.T.S. S.R.L for supplying the consolidating product Nanorestore®. The authors are grateful to Laura Tormo and Marta Furió of the Natural Science Museum (CSIC) for providing the ESEM photographs and analyses. Special thanks go to Emilio Matesanz from XRD CAI (UCM) for his help with the XRD analyses and Juan Luis Baldonedo from Microscopy and Citommetry Centre (UCM) for his support with the TEM analyses.
- Calcium carbonate polymorphs
- Calcium hydroxide
- Relative humidity