Assessment of Lime-Based Mortars to Conservation of Architectural Remains from Archaeological Excavations

Next to the archaeological explorations, conservation and restoration of remains of monuments in the fields have received the attention of scientific archaeological excavations. Exposure of new finding materials to the microclimate conditions of earth surface causes to encourage their degradation process. Since a number of sites in the north and northwest of Iran encounter precipitation humidity and consequently the destruction of architecture remains, it appears that isolating outer remains of these structures using the compatible mortar is one of the best methods to reduce their damage. Lime mortar is appropriate for this purpose owing to its acceptable characteristics against the humidity. In this research, cow dung ash, rice husk ash and wood were used to optimize the lime mortar. The mix of these materials with lime paste prepared 6 different types of lime-pozzolan mortar. To determine the appropriate sample in terms of durability and consolidation against the natural cycles, accelerated aging tests including wetting and drying cycles, freezing & thawing and salt attack cycles as well as physical characteristics (densitometry, porosimetry, water absorption, and durability) for all types. The results of above processes indicated that the compositions of cow dung ash pozzolan’s have better resistance to the aging cycles and other physical experiments. Using XRD and XRF analyses, the structure and the amount of mineral phases were determined. Based on the results, it is recommended that lime mortar (optimized with cow dung ash) be used in the historic monuments and the humid climates of the north and northwest of Iran.