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2006 Award of Distinction

Uch Monument

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Technical Brief

Investigating the Condition of Monuments

The Uch Monument Complex is one of the most thoroughly investigated monument complexes in the history of Pakistan. Data from these investigations underpinned the design of the conservation interventions. The following aspects were studied and analyzed: (i) the methods of construction used in the monuments, (ii) the fabric of the monuments, (iii) the characteristics of the materials, (iv) the ways in which the monuments have and are continuing to weather and (v) the nature and intensity of the damage that has occurred over time. The latter three types of studies are described here.

Materials Tests

The studies conducted on material samples from the monuments were aimed at understanding the basic physical properties of the construction materials and their deterioration. Samples were taken of the following: old and new brick; the raw material used in the manufacture of new brick; mud mortars; plaster renders; lime and gypsum mortars; glazed tiles, blocks and bricks; and the soil in the immediate vicinity of the monuments. The characteristics studied in the laboratory included density, porosity and water absorption capacity, wetting and drying rates, water vapour absorption rates and chemical and mineralogical composition. The examination of thin sections (slivers mounted on glass slides) of the material using analytical tools such as X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) gave insight into the mineralogical composition of materials and their physical formation and structure.

The most important aspect of these studies was the extent to which the interplay between water movement, the presence of soluble salts, and the physical and mineralogical properties of the materials affected the weathering processes of the buildings.

Weathering

Through studying the weathering of the monuments in Uch, a comprehensive taxonomy of weathering forms was established. The weathering forms were classified into five major groups: (i) loss of material (i.e. from erosion or vandalism), (ii) disengagement of material (i.e. loss of adhesion of plaster and bricks), (iii) minor cracks, (iv) discolouration and deposits (i.e. from dust and bird droppings) and (v) structural deformation. Using this taxonomy, a detailed recording of weathering effects was mapped onto measured drawings of the structures to guide the conservation planning.

The monuments were found to be vulnerable to a range of factors, such as rain and wind, which had a particular effect on the buildings because of the materials used and the type of construction. For instance, the interiors of the buildings that were once protected had become exposed to external weather conditions over time, leading to loss of structural timber elements, which in turn led to instability of the walls. The exposed edges of broken and sheared walls enabled rainwater to penetrate deep into the fabric of the walls, which are composed of materials such as mud mortars, which are very susceptible to water damage. The lack of good drainage in and around the building allowed groundwater to move up into the fabric of the building. Through wet and dry cycles over the years, the presence of water within the building fabric caused the crystallization of soluble salts and the swelling and shrinking of clay particles, leading to dislodgement and disengagement of materials.

Classification of Damage

Based on the intensity and distribution of the individual weathering forms, five damage categories were identified, ranging from “very slightly damaged” to “very severe damage”. “Very slightly damaged” refers to damage that is not really harming the building fabric, is not causing major deterioration problems and can be arrested with a simple intervention. “Slightly damaged” includes damage from rising damp and rounding or notching of bricks in the superstructure. “Moderate damage” includes severe and lasting humidity stains and large cracks in the domes. “Severe damage” includes loss of the original plaster or glazed elements and certain kinds of structural cracks. “Very severe damage” means, for instance, structural deformations threatening the stability of the structure. These categories provided the basis for estimating the urgency and types of interventions necessary to arrest further deterioration of the monuments.

Adapted from “Uch Monument Complex” UNESCO Asia-Pacific Heritage Awards entry submission