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(CH 2CH2O)3CH3)2] (1) and [Ca(O(CH2CH2O)3CH2CH 3)2] (2), together with [Ca(OCH2C(CH 3)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(CH3CH 2OH)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.