A new ingredient to improve Chinese traditional hydraulic lime and its assessment on stone heritage conservation

Abstract

AbstractGinger nut, AGA soil, and shell lime are the primary building limes used in traditional Chinese architectural sites. They have been widely researched and developed for restoring rock and soil heritage over the last decade. Previous studies have shown that these materials are compatible with weathered rock in terms of mechanical properties and environmental adaptability. In this study, metakaolinite was added to Chinese hydraulic limes to improve the mortar abilities. The basic properties and weather abilities of the mortars were evaluated. The characteristics of carbonation and hydration were analyzed over 900 days. The results indicated that the early strength improved and the contracting rate reduced when metakaolinite was added. The shell lime mortar was improved considerably compared with the modified ginger nut and AGA soil. The lime mortar content was determined using the X-ray diffraction results. The carbonation and hydration characteristics revealed that the metakaolinite aided the generation of hydraulic products (Ca2Al2SiO7·nH2O and β-CaSiO3·nH2O), particularly in the early stage. The microstructures were observed by scanning electron microscopy, which revealed more uniform and consolidated structures when metakaolinite was added.