Characterization of historical mortar from ancient city walls of Xindeng in Fuyang, China

The goal of this investigation is to characterize the mortar from the ancient city wall of Xindeng in Fuyang, Hangzhou (China), which reveals a history of nearly 1800 years. Several approaches were used to analyze seven specimens obtained from this ancient city wall, and physical properties, mechanical performances, binder/ aggregate ratios of these specimens were then determined. However, the mixture compositions as well as the mix design vary greatly among different locations of the city wall. The results indicate that the historical wall is mainly composed of hydrated lime and sand, and parts of the specimens also contain clay. Meanwhile, calcite and quartz are the major phases present in the historical wall mortars with several impurities. Further, the specimens' great strength and large apparent density are related to the abundant aggregates used and the presence of the fragments of blue brick within the specimens.