New calcium alkoxides for consolidation of carbonate rocks. Influence of precursors' characteristics on morphology, crystalline phase and consolidation effects

New ambient temperature liquid calcium alkoxides, [Ca(O(CH2CH2O)(3)CH3)(2)] (1) and [Ca(O(CH2CH2O)(3)CH2CH3)(2)] (2), together with [Ca(OCH2C(CH3)(3))(2)] (3), were synthesised by reaction of ammonia-activated calcium with the appropriate alcohol. Their potentiality as stone consolidant products was investigated and compared with those of other alkoxides: [Ca(OCH2CH3)(2)(CH3CH2OH)(4)] (4), [Ca(OCH3)(2)] (5), [{Ca(OCH2CH2OCH3)(2)}(9)] (6), already described in the literature. Reaction of 1-3 with the atmosphere was studied, final products analysed and kinetic pathways investigated. The reaction produces CaCO3 and the vaterite/calcite ratios observed in the coatings generated from isopropyl alcohol solutions of 1-6 were found to considerably vary with the alkoxide precursor, which has a strong influence also on the morphology of the produced films. Furthermore, their efficiency as stone consolidants was tested by ultrasound measurements.