An approach for a rapid determination of the aging time of lime putty

tA method for determining the effective and long aging time of lime putty, a feature which favors betterquality of the corresponding lime mortar, is proposed. Different quicklime precursors were slaked underan excess of water for different times ranging from 3 to 66 months. Each of resulting lime putty was dehy-drated by lyophilization and after characterized by thermo-gravimetric analysis (TGA), X-ray diffraction(XRD) analyses, scanning electron microscopy (SEM), and surface area. Taking into account the impuritycontents present in the starting quicklime, the mineralogical composition of each lime putty was deter-mined from the weight loss related to the amount of adsorbed water and to the weight losses relatedto the decomposition of mineral phases present in the lime putty such as brucite, Mg(OH)2, portlandite,Ca(OH)2and calcite, CaCO3, respectively.The total mineralogical composition of lime putties aged for a time higher than 12 months was closeto the expected value of 100%, while such value resulted lower than 100% for lime putties aged for lowertimes.To justify such result, an incomplete hydration of the quicklime precursor must be considered for limeputties aged for lower times. The delayed hydration can be related to the presence of over burnt of someparticles of lime present in the starting quicklime.