Types of lime binders in mortars used for the construction of the Ming Great Wall of China and their importance for the development of a conservation strategy

Research on the Ming Great Wall reveals that dolomitic lime, a high-strength binder with low porosity, was predominantly used in its construction around Beijing and Hebei provinces. This finding challenges the current conservation principle of preserving the wall as a ruin, suggesting instead that calcium-rich lime binders should be employed for conservation or restoration to mitigate damage caused by reactions between dolomitic lime mortars and air pollutants. The study analyzed chemical and mineralogical compositions of original mortars, identifying aggregate-free textures in both dolomitic and calcium-rich lime mortars. Additionally, it proposes natural hydraulic lime and pozzolana-gauged binders as more compatible alternatives for structural consolidation.

Dettmering, T., & Dai, S. (2022). Types of lime binders in mortars used for the construction of the Ming Great Wall of China and their importance for the development of a conservation strategy. Built Heritage, 6(1). https://doi.org/10.1186/s43238-022-00047-z