الأحد، 28 أكتوبر 2012

STONE RESTORATION part 1


STONE RESTORATION PRACTICE IN PALESTINIAN TERRITORIES:
A CASE STUDY FROM JERUSALEM
part 1
 Shadi Sami Ghadban*
Marwan  Ashhab,
Dr. Shadi Ghadban is a teaching staff member at the Department of Architectural Engineering/ Faculty of Engineering at Birzeit University, Palestinian Territories. His academic and research activities are oriented towards the problems of local traditional architecture and has several publications on this field. In addition, he has a wide experience, as consultant and project manager for a good number of rehabilitation and restoration projects in several major Palestinian cities, including Bethlehem and Hebron.

Eng. Marwan Al- Ashhab, is a civil engineer and holding a Master degree in the field of “Restoration and Rehabilitation of Buildings” from the Higher Institute of Islamic Archaeology, Jerusalem University. Since 1998 he established his own consulting office and started his activity as contractor for rehabilitation and restoration of old buildings in the city of Jerusalem. He is a research fellow at the Department of Architectural Engineering at Birzeit University.

ABSTRACT

The aim of this research is to study the present practice applied to restoring and improving the status of the stonework in the historic buildings in Palestine, concentrating on this practice within the boundaries of the Old City of Jerusalem, Palestine. This requires identifying the stones’ current conditions and the causes behind their deterioration, and defining the appropriate criteria to be monitored in dealing with the effects of ongoing deteriorative factors on the maintenance and rehabilitation of these stones, concentrating on the phenomenon of porosity.
The methodology implemented in this research is based on both tangible and intangible components. These include a survey of the literature, direct observations through site visits, the photographing of certain cases, and collecting and analyzing samples from the various sites as well as from among the building materials available on the local market. All the samples were subjected to laboratory testing at Birzeit University in order to determine the properties of the materials to be used in the restoration process.
The research concludes with the drafting of specific recommendations and suggestions to be used in the field of stone restoration practice.

Keywords: Stone properties, Deteriorative Effect, Laboratory Testing, Historic Buildings, and Authenticity.

Postal Address: Department of Architectural Engineering
Faculty of Engineering- Birzeit University
Birzeit- P.O.Box (14)
Palestine
Tel: +972 2 2982119
Fax: +972 2 2982984

Running Head: STONE RESTORATION: A CASE STUDY FROM JERUSALEM

INTRODUCTION

Architecture in Palestine has been a product of the larger cultural development along the eastern shore of the Mediterranean basin, and has been influenced by historical events that repeatedly caused great dislocation and mixing of ethnic groups. One result has been diverse populations – having different governing systems, customs and other cultural traditions –living very close together. In this way, the necessary conditions were established for mutual influence to take place, during the process of the formation, development and enrichment of inventive traditions and values [1].
The historical cities of Palestine were thus formed and shaped as a result of this remarkable dislocation and juxtaposition of ethnic groups. They have undergone in the past, and are still increasingly exposed to, a long process of development beginning (in the case of the city of Jericho) some 10,000 years ago. The material traces of these cities reflect long centuries of human history condensed in a limited area, presenting to us the living image of the local historical and cultural environment over time (Fig 1).
Stone is considered the main building material in these cities due to its abundance; its splendid display of color ranging from white, to yellow, pink and gold; its inherent strength to resist different weather conditions; and its particular geological characteristics. This reliance on stone construction is reflected in a substantial range of historic buildings, structures possessing high cultural heritage value and authentically reflecting the various civilizations that prevailed in this region.
In the case of Jerusalem, the city not only has experienced some 5,000 years of human development, but it still occupies a special place in the world, especially as the focus of three  great religions: Judaism, Christianity and Islam [2]. Throughout its historical development spanning many centuries, this city has accumulated many occupational layers, and was subjected at least eighteen times to significant damage from natural or manmade sources of destruction [3]. The Old City in particular has been substantially rebuilt several times, reaching its current configuration in the  period of Ottoman rule [4].
The city witnessed periods of major restoration during the Eighteenth, Nineteenth and Twentieth Centuries, focused mainly on the early Islamic and other religious monuments in Jerusalem. This trend was one part of a larger program implemented by the Ottomans in order to control the region, and also the result of competition among various religious groups and foreign powers for primacy in the city [5].
Beginning with the British Mandate over Palestine in 1920, continuing during the  period of Jordanian rule (1948-1967), and finally under the Israeli occupation (1967-present), the restoration process proceeded slowly, and now a trend is evident toward growing awareness of issues concerning the rehabilitation or restoration of major religious or public buildings and compounds in the Old City. The present initiatives are largely funded by non-governmental organizations, employing guidelines and techniques reflecting the European experience in the field of restoration, and technical standards and charts  approved by international organizations such as UNESCO, ICOMOS, ICCROM, REHABIMED, etc. At this stage, the stone restorations have continued according to previous established practices, mainly those related to replacing of damaged or missing stones, plastering and pointing and treatment of any detectable deterioration in the stones of the historical buildings. Thus far, however, this practice has not considered the physical characteristics of the stone material itself, especially its ability to withstand various deteriorative factors.
In 1993, the Palestinian Authority was established according the provisions of the Oslo Interim Agreement. As a result, since about 1998 several large-scale restoration and rehabilitation projects, both international and local initiatives, have been undertaken, giving rise to a new Palestinian awareness towards the restoration and rehabilitation of buildings (one of its main objectives being to counteract the Israeli campaign of “Judaizing” the Old City of Jerusalem). Thus, various organizations, local and international, started restoring and/or rehabilitating different public and residential structures. This work has proceeded sporadically and at a low level, continuing with the same techniques as used in the previous periods. Specifically, all the operations were carried out without any sort of laboratory testing, analysis that would obviously help in defining the quality of both the old, existing materials employed in the buildings and the new materials to be used in any restorations.
Thus, the main objective of this study is to examine the present practices used in the restoration of stonework within the historic and traditional buildings in Palestine, through a case study from Jerusalem, concentrating on how to help upgrade the prevailing practice through the proper, informed selection of materials, according to standardized, measurable criteria, all the while preserving the materials’ authenticity as to their color and shape, and insuring the compatibility between the old and the new stones, and that they will hold up optimally in the future against the various deteriorative factors. This requires identifying the current condition of these stones, the causes behind their deterioration, and defining the appropriate criteria, within the practices prevailing in the country, for managing better maintenance and restoration process.
To achieve this objective, a methodology based on both tangible and intangible components shall be presented and implemented in this paper. It includes a survey of the existing literature, field observations through site visits, the photographing of certain cases of deterioration, and collecting and analyzing samples from various existing structures as well from the building materials available on the local market and commonly used in restoration operations. All of the collected samples were subjected to laboratory testing at Birzeit University laboratories in order to examine their nature and properties. Of special interest were those properties of the materials which, in the context of a rehabilitation process, influence long-term durability, i.e. factors which will support preserving the authenticity of the stone structures while also insuring their maximum stability against various deteriorative changes. These findings will help in the selection of the proper stones for restoration of each case separately, and will guide the preparation of the necessary mixtures (mortars, fillers, etc.) which can be custom-made for specific applications and will thus be suitable for the most effective restoration actions in a wide range of future projects.

.....to be continued....

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