The current situation of Kulangsu historical architectural mortar and the reasons for its performance degradation were studied and analyzed through field researching and sampling analyzing. The results show that the historic buildings in Kulangsu are mostly made of lime-based mortar, most of which are lime clay mixed mortar and a few are lime mortar, and serious degradation such as cracking, mildew, water seepage, weathering and spalling has been widespread. The external causes of the deterioration of lime-based mortar performance are the long-term effect of sea wind and salt fog erosion and the combination of high temperature, high humidity and other destruction factors. The closer the buildings are to the coastline, the more severe the damage is. The gas-hardness property of lime and the low pozzolanic reaction among lime, clay and quartz sand are the inherent factors resulting in the low compressive and flexural strength of the lime-based mortar itself, the low bonding strength between the base block and it, and its poor durability. Under the guidance of the "raw materials, original process, and minimum intervention" principle of the rehabilitation of historical buildings, the restoration method of using modified shell ash mortar as reinforcing material is put forward. This method is to add active silicon (aluminum) material to the traditional shell ash mortar through modification technology so that the gas hard shell ash can be transformed into a cementitious material which can possess both hydraulic and gas hardness, and then use this modified lime mortar as a reinforcement material to replace the deteriorated mortar construction so as to complete the restoration. © 2021, Materials Review Magazine. All right reserved.
