A significant comparison between magnesium-based binder and other inorganic cementitious materials for the restoration of brick-carved cultural relics

The uniqueness of brick-carved cultural relics causes a higher requirement for restoration techniques and repair materials. Considering the weather resistance and compatibility with the original substrate bricks, three types of inorganic binders were selected as alternative options for brick carving restoration: Ca-based hydraulic lime, Si-based silica sol, and Mg-based magnesium oxychloride. Multiple experiments were conducted to investigate the compatibility of the replica bricks produced using these binders. The adhesive properties and infiltration reinforcement of the binders were also taken into consideration to evaluate the feasibility of these materials’ application for the restoration of brick-carving cultural relics. The results showed that the Mg-based cementitious material led to the best performance, maintaining their original physical properties while restoring the original cohesion. A successful in situ test was conducted on the Southern Song brick carvings (1152 CE) inside the Liuhe Pagoda (Fig. 1 a) in Hangzhou.