Structural Faults in Earthen Archaeological Sites in Central Asia: Analysis and Repair Methods

The first aim of this paper is to study the main symptoms of structural decay of earthen archaeological sites, with special reference to those located in the central Asian loess clay belt: Kazakhstan, Kyrgyzstan, and Tajikistan. The Silk Road sites considered in this paper are mostly located in extreme environments with temperature reaching -20 degrees C in the winter and 50 degrees C in the summer, and such conditions provide an ample background for studying structural faults. Before the collapse of the Soviet Union archaeological excavations in central Asia were neither followed by conservation work, nor by backfilling. The fact that none of the sites considered in this study was previously conserved adds value to the research because it shows the behaviour of soil in its natural environment (especially mud brick and rammed earth). The study explains that the main causes of decay can be broadly classified as: rheological (or water mismanagement), man-made, and due to high content of soluble salts. The second aim of the paper is to propose structural repair methods and guidelines for the most common mechanisms of decay. This is drawn from practical experience in the field as attained by the author in several central Asian projects managed by UNESCO. The existing literature on the conservation of archaeological sites shows scarce information on the structural consolidation of earthen structures. It is therefore crucial to transfer such practical knowledge to those practitioners and conservators working in similar projects elsewhere. In order to do so, the paper provides a thorough explanation on: stitching technique for cracks, conservation of leaning walls, repair of basal erosion, and shelter coating. Another important aspect is the use of emergency conservation activities