Journal of Architectural Conservation

Volume 3 Issue 2 July 1997

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The Leaning Tower of Pisa

See: 'Propping up Pisa - Part One' by John Burland


Propping Up Pisa – Part One John B. Burland

A Comparative Study of Alkoxysilanes and Acrylics in Sequence and in Mixture  Frank G. Matero and Anne B. Oliver

The Conservation of Singapore's Chinatown Sim Loo Lee

The Susceptibility of Historic Brick Masonry to Decay S. Pavia Santamaria and J. R. Bolton

The Conservation of Monasteries in the Western Himalayas Jyoti P. Sharma and Janhwij Sharma



Conservation: Art and Science

David Watt


As the Journal becomes more widely known and respected, it is encouraging to see that it is attracting an increasing number of international papers. We have much to learn from how often common problems are dealt with in different ways. Despite cultural differences between countries, the academic and professional skills required to undertake conservation need to be shared – this is, above all, the theme of the papers in this particular issue.

There is also another divide that if bridged will benefit those concerned. The view that architectural conservation belongs solely to those from an arts background has stifled dialogue and contribution for too long. What the sciences can bring is another dimension to our overall understanding of buildings; one that is becoming increasingly important in conserving the materials and contents that together form the entity that we now value and wish to retain.

It is therefore encouraging to see examples of where such skills and experience are being used to good effect. The work of Professor John Burland at Pisa in Italy has become widely acclaimed and is a model of clear and sound reasoning, coupled with imagination and attention to detail. In the first of a two-part paper looking at the engineering solutions for the famous leaning tower, its construction and subsequent behaviour are considered before, in part two, stabilization measures are presented.

Janhwij Sharma and his wife have spent a great deal of time learning and understanding about the architecture and culture of the western Himalayan region. In The Conservation of Monasteries in the Western Himalayas, the authors provide a fascinating account of the history, construction and conservation of the monasteries in this part of India.

As conservation comes to be seen as a sound and sustainable way of managing resources, the value and importance of historic areas and buildings can provide the impetus for evolution and growth. The Conservation of Singapore’s Chinatown by Dr Sim Loo Lee considers how this district has combined conservation and commerce in its development, and what effects such change has had on its character and identity.

The subject of change is also covered by Michael Taylor in Conservation in a Multi-Cultural Environment. For those towns and cities that support ethnic communities, the question of how to respond to and embrace the needs and inspirations of differing cultures, whilst retaining the intrinsic qualities of the setting, requires a level of understanding and commitment that challenges current priorities and responses.

Moving from the macro to the micro scale of conservation, we have two papers that address particular issues of concern to those responsible for the repair and maintenance of historic fabric. In A Comparative Study of Alkoxysilanes and Acrylics in Sequence and in Mixture, Frank Matero and Anne Oliver consider and report on the use of acrylics and silanes for the conservation of stone. Understanding the role of such treatments in conservation can only come from controlled and well-documented usage, and the authors should be congratulated for their approach and presentation.

Developing an understanding for how materials deteriorate and decay is essential in determining the most appropriate course of action for remediation. The Susceptibility of Historic Brick Masonry to Decay by Sara Pavia Santamaria and Jason Bolton examines the effects of moisture and salts on the brickwork of San Bartolome Church in northern Spain, and explains the various methods of analysis used in their work.


Propping Up Pisa – Part One
John B. Burland


This paper describes some of the engineering aspects of the work of the Italian Prime Minister’s Commission for stabilizing the leaning tower of Pisa, and is presented in two parts. Part One presents a brief history of the construction and subsequent behaviour of the Tower as deduced from careful measurements made on the masonry courses. The deduced history of inclination of the Tower has been used to calibrate a sophisticated computer model of the Tower and underlying ground. Some surprizing findings of recent studies of the motion of the Tower are presented. Part Two of the paper describes how these studies were used in developing the short-term stabilization measures that have been implemented by the Commission. Measurements made on the response of the Tower to these measures are presented. Finally, the work of the Commission in developing a permanent solution is summarized.


John B. Burland FEng, FICE, MIStructE, DSc(Eng)

The author studied civil engineering at the University of the Witwatersrand, Johannesburg and gained his early practical experience with Ove Arup and Partners in London. In 1980 he was appointed to the Chair of Soil Mechanics at the Imperial College of Science, Technology and Medicine.


A Comparative Study of Alkoxysilanes and Acrylics in Sequence and in Mixture

Frank G. Matero and Anne B. Oliver


A limestone column at Mission San Jose, San Antonio, Texas (USA) exhibited the friability, microcracking and flaking that is typical of salt-contaminated stone. Mixtures of acrylic resins and alkyl alkoxysilanes are frequently used to treat these problems. The deterioration was localized, however, and it was not advisable to introduce the potentially adverse effects of the acrylic in the mixture to relatively sound stone. The adhesion of subsequent infills would also be adversely affected by the water-repellency of the silane. Sequential applications of acrylic and silane would be more practical, flexible, and potentially more effective. The interaction of these materials, and their effectiveness when used in sequential order, has been little studied.

An experimental program was designed to quantify differences in the physico-mechanical properties of models that were caused by the application of acrylic and silane in sequence, rather than in mixture. Test results indicated that the method of application did not cause great differences in most properties of the treated models, but that mixtures were somewhat more effective. Based upon these results, and the treatment requirements of the column, the limestone was treated with a sequential application of an acrylic resin and an alkyl alkoxysilane. 


Frank G. Matero BA, MSc
Frank G. Matero is Associate Professor of Architecture, Chairman of the Graduate Program in Historic Preservation, and Director of the Architectural Conservation Laboratory, University of Pennsylvania.

Anne B. Oliver BA, MSc
Anne Oliver is an architectural conservator in private practice. Since 1993 she has worked primarily at prehistoric and historic archaeological sites in the American south-west, developing and implementing preservation plans for both materials and sites.


The Conservation of Singapore’s Chinatown
Sim Loo Lee


Chinatown is the largest historic district in Singapore gazetted for conservation. Besides possessing buildings of great historic significance and architectural value, the activities reflect the cultural heritage of the Chinese community. This paper analyses the impact of conservation on Chinatown. This is done through a field survey of the shophouses and an analysis of the use before and after restoration. The analysis shows that Chinatown has become more commercial in character. Residential use has declined sharply, having been replaced by office use. Although the conservation policy has succeeded in preserving the urban fabric and retaining traditional trades in the restored shophouses of the core area, the decline in residential use has produced a less vibrant Chinatown.


Sim Loo Lee PhD (NUS), LLB (Hons), Barrister-at-law (Lincoln’s Inn)
Dr Sim Loo Lee is a senior lecturer in the School of Building and Estate Management, National University of Singapore. She teaches built environment and real estate law.


The Susceptibility of Historic Brick Masonry to Decay
S. Pavia Santamaria and J. R. Bolton


The aim of this paper is to determine why, and in what manner, brick decays. Samples of brick and salt efflorescence were taken from a church in northern Spain and analyzed for mineralogical and structural changes, and soluble salts. The effects of decay on brick mineralogy and texture were studied using polarizing microscopy and scanning electron microscopy (SEM) provided with energy dispersive X-ray analysis (EDXA); salts were identified by X-ray diffraction (XRD). Physical tests were used to assess the susceptibility of bricks to decay by moisture, freeze-thaw cycling and salt weathering. Mortars were examined to determine if they contributed to salt decay process in the brick. The paper concludes that, for the samples investigated, salt weathering predominated. Many of these salts, which include halite (NaCl), niter (KNO3) and gypsum (CaSO4), as well as aluminium salts, were transported from the ground into the wall by means of capillary action.


Sara Pavía Santamaría BSc, PhD
Dr Sara Pavía Santamaría has worked as a post-doctoral Fellow at Trinity College Dublin since 1994, and now lectures on the decay of building materials and conservation at Trinity College Dublin and University College Dublin.

Jason R. Bolton BA
Jason R. Bolton completed his first degree in ancient history and archaeology at Trinity College Dublin. He has carried out research work on archaeological materials and structures since 1994, and specializes in underwater archaeology.


The Conservation of Monasteries in the Western Himalayas 

The Conservation of Monasteries in the Western Himalayas 

Jyoti P. Sharma and Janhwij Sharma


This paper considers monastic architectural practices in the western Himalayan region of north India and its close association with Tibetan architecture. It looks into some of the issues that have led to the current deterioration of some of the important Buddhist structures, and considers three prominent monasteries at Spiti in Himachal Pradesh for recording. It further suggests a need for thorough research, documentation and extensive exploration into the religious and architectural practices, and what measures should be adopted to safeguard the future of these monasteries.


Jyoti P. Sharma BArch(Dist)
Jyoti P. Sharma is an architect and currently lectures in architecture at the Department of Architecture, CR State College of Engineering, Murthal, Haryana (India).

Janhwij Sharma BArch  

Janhwij Sharma is a practising architect in India. He is also a visiting lecturer for the Department of Architecture, CR State College of Engineering, Murthal, Haryana (India).

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