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The Survey Conclusions
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General stability. In general Jerusalem's city walls are stable. In a number of specific places such as the moat, the vicinity of Dung Gate etc. localized problems are apparent in the wall's stability.
Load bearing elements
Foundations. The wall foundations were not examined in the current survey. No cracks or other distortions in the wall were discovered that indicate problems with the support of the monument.
The sides of the wall. In several places a localized leaning of the facades was discovered. This inclination indicates the beginning of a destructive structural process within the wall. In these places it is necessary to monitor the structural changes (deformations) in order to control the process. If the deformation develops it will be necessary to reconsider constructive intervention such as the use of anchors.
Vaults. There is localized deterioration in the vault stones that are in the sentry posts and towers. Nevertheless, these are stable and their geometric shape is not deformed.
The problems and main causes of deterioration
The division into problems and causes is not unequivocal. Each problem is also a factor in the deterioration processes and ongoing destruction (see Fig. 1). Water seepage is the chief problem in the cycle of destruction in Jerusalem's city walls. Most of the problems in the wall stem from water seeping into it, primarily by way of the horizontal surfaces; these problems exacerbate that of the water seepage and cause a new cycle of destruction.
1. Destruction of the building materials. The decay of the stone and bonding materials is the fundamental problem in the conservation of the walls and their rehabilitation. In order to rehabilitate Jerusalem's city walls the original building material needs to be conserved.
2. Vegetation taking root. This undermines the structure of the wall. It disintegrates the adhesion of the bonding material and exacerbates the problem of water seepage.
3. Missing bonding material. Joints that are devoid of bonding material damage the stability of the wall and intensify the seepage of water into the core of the wall.
4. Cracks. The formation of cracks leads to damage in the stability of the material and increases the seepage of water into the core.
5. Modern intervention. The chief destructive factor effecting Jerusalem's city walls is the improper intervention that was done during the twentieth century which stems from a lack of awareness and conservation knowledge. This intervention includes:
A. The creation of concave surfaces at the top of the wall which cause water to seep and promote weathering and destructive processes.
B. Filling joints in with cement is irreversible damage that is manifested over the course of many years by the decay of the stones.
C. Incorrect development in the vicinity next to the wall: causing water to drain in the direction of the wall and through the wall, forming low regions next to the wall in which water can accumulate, planting trees and gardens next to the wall etc.
The nature of the weathering processes in the wall
Soft limestone was utilized between hard limestone in the construction of the wall. In the twentieth century the joints were pointed up with cement-based sealing material. As more water penetrated into the wall the deterioration of the soft limestone intensified. Even though the weathering in the soft limestone is localized it damages the entire monolithic massiveness of the stone structure. The overall stability of the wall is likely to be undermined as a result of this. Most of the problems are apparent on the upper levels of the wall, below the horizontal planes: the tops of walls, crenellations, sentry paths and firing slits - and on the low level, which functions as a retaining wall that holds back the soil on the inside facing the Old City. The crenellations are the most vulnerable component in the wall and the one that most influences the appearance of Jerusalem's city wall. Conservation of the original crenellations is of paramount importance. The outer facades are well-preserved compared to the state of the facades that face the Old City. The towers along the wall, in which there are a relatively large number of horizontal surfaces, are more neglected compared to the general state of the wall. The damage in the gates is also greater compared to the general state of the wall.
The Survey Recommendations
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