Challenges in Characterization and Development of Suitable Historic Repair Mortars

The importance of compatible restoration of historic masonries cannot be overemphasized, as it helps maintain the historic structures for sustainable development, economic growth, and the representation of a country's history. This paper acknowledges the existence of extensive research work on historic mortar characterization, the proposition of restoration materials, and the awareness raised about the use of incompatible restoration materials. However, the concept of historic mortar characterization still faces some challenges in methodology, material sampling, and mortar decay that need to be confronted. The problem extends further to designing and producing compatible restoration mortars for historical monuments. The work has not been extended to evaluate the compatibility and durability of the designed mortars. This creates uncertainty about the effectiveness of such proposed solutions. These could be overcome by analyzing the physical, chemical, mineralogical, and mechanical properties of the original representative mortar samples collected from historic structures and the proposed repair mortars before executing repairs. It is believed that investigations into the mix designs help achieve successful restoration work. This review presents the recent advances in historic mortar characterization and is intended to be a useful tool for historic restoration teams when tackling conservation activities on historic masonries.