Handbook of Polymers in Stone Conservation

316 Pages·2014·12.683 MB·English

by  Princi, Elisabetta

Handbook of Polymers in
Stone Conservation
Elisabetta Princi
A Smithers Group Company
Shawbury, Shrewsbury, Shropshire, SY4 4NR, United Kingdom
Telephone: [phone] Fax: [phone]
http://www.polymer-books.com
First Published in 2014 by
Smithers Rapra Technology Ltd
Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK
©Smithers Information Ltd., 2014
All rights reserved. Except as permitted under current legislation no part
of this publication may be photocopied, reproduced or distributed in any
form or by any means or stored in a database or retrieval system, without
the prior permission from the copyright holder.
A catalogue record for this book is available from the British Library.
Every effort has been made to contact copyright holders of any material reproduced
within the text and the author and publishers apologise if
any have been overlooked.
ISBN: 978-1-84735-712-0 (hardback)
978-1-84735-703-8 (softback)
978-1-84735-546-1 (ebook)
Typeset by Argil Services
A
cknowledgments
I express my gratitude to the many colleagues and associates who have provided
support during the preparation of this book. My particular thanks are due to the
website The Macrogalleria for allowing use of their images.
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Handbook of Polymers in Stone Conservation
iv
P
reface
Conservation of historic monuments is a means of continuity with history because it
keeps alive the cultural scene of the period to which they belong. The world is rich in
various types of built heritage, and a large proportion of monuments are made of stone.
Stone artworks come in various forms: mineral specimens, sculpture, jewellery, tools,
fossils, cave paintings, buildings, and bridges. Some are resistant if used outdoors on
the ground, whereas others are more fragile and brittle. If stone artworks are handled
inappropriately, they can break.
Deterioration of stone is familiar to anyone who has looked closely at a historic
building or monument. A few stones seem little affected by centuries of exposure to
the weather, but most are undergoing gradual deterioration by weather and pollution.
Hence, stone-based cultural heritage is slowly (but inexorably) disappearing, inducing
investigations focused upon it.
An understanding of the mechanisms responsible for stone decay is needed to develop
optimal methods for stone protection, and is the basis of a conservative approach.
To reach the goal of preserving stone-based materials, describing stone decay as
well as measuring its extent, severity, rate, causes and mechanisms, is essential.
Investigations related to stone deterioration must take into account the wide range
of types of rocks having different mineralogical and physical characteristics and their
varying weathering responses under different climatic and environmental conditions.
Afterwards, suitable methods and materials may be studied and set-up to help the
stone to survive. In response to this, numerous research projects, publications and
conferences dealing with stone conservation have facilitated the worldwide exchange
of information.
Today, a strong scientific approach is accompanied by an encouraging number of
new conservation treatments, methods, and tools. The key challenge for the future is
to ensure that the resources for applied research, technology transfer, and long-term
testing are improved. Progress in these areas has undoubtedly been evident over the
last 15 years, but structural gaps remain between researchers and practitioners as
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Handbook of Polymers in Stone Conservation
well as between old assumptions and rapidly evolving new knowledge. To preserve
our heritage in stone, we must build support for larger-scale and longer-term studies
and technology-transfer projects. In several cases, exciting solutions to stone-
conservation problems are available, but resources to test and implement these
solutions appropriately are not.
In the past 25 years, conservators in many countries have turned to new forms of
synthetic polymers for the preservation of sandstone, limestone, marble, and other
building stones. Nowadays, there is controversy about applying polymers to stone
to provide stabilisation. The primary question is how an organic material can make
inorganic rock stronger. Use of polymeric materials shows some limitations and gaps
that further studies will be able to fill and overcome, thereby helping stones to survive.
This handbook is an overview that maps the ‘landscape’ of stone conservation,
focusing particularly on the employment of polymeric materials. It is intended to
serve as a useful point of entry into this exciting research area. It looks first at stone
deterioration and then discusses the use and effectiveness of polymeric materials.
The final aim of this book is to explain if it is possible to protect stone from weathering
in certain ways: conservation through polymer consolidation may be the correct
answer.
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C
ontents
1 What is a Polymer? ....................................................................................1
1.1 Introduction ....................................................................................1
1.2 Polymer Synthesis ...........................................................................4
1.3 Polymer Structure .........................................................................11
1.3.1 Constitution and Configuration .......................................12
1.3.2 Conformation ..................................................................17
1.4 Crystalline and Amorphous Polymers ...........................................18
1.5 Thermal Properties .......................................................................21
1.6 Mechanical Properties of Polymers ...............................................28
1.7 Copolymers ..................................................................................31
1.8 Polymer Blending ..........................................................................33
1.9 Composite Materials .....................................................................38
1.10 Elastomers ....................................................................................40
1.11 Adhesion and adhesives ................................................................42
1.12 Ageing and Degradation of Polymers ............................................43
2 Stone Materials ........................................................................................47
2.1 Introduction ..................................................................................47
2.2 Rocks: General Classification ........................................................48
2.2.1 Eruptive or Igneous Rocks ...............................................51
2.2.2 Metamorphic Rocks ........................................................52
2.2.3 Sedimentary Rocks ..........................................................53
2.3 Stone Properties ............................................................................54
2.3.1 Rock Hardness ................................................................56
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Handbook of Polymers in Stone Conservation
2.3.2 Break Resistance ..............................................................56
2.3.3 Specific Weight and Porosity ............................................56
2.4 Silicates .........................................................................................58
2.5 Sandstone .....................................................................................64
2.6 Granitic Rocks ..............................................................................67
2.7 Porphyries and Basalts ..................................................................67
2.8 Calcium Carbonate .......................................................................69
2.9 Limestone .....................................................................................71
2.10 Marble ..........................................................................................73
2.11 Gypsum ........................................................................................75
2.12 Lime and Lime Mortars ................................................................75
2.13 Cement and Concrete....................................................................77
3 Stone Degradation ....................................................................................81
3.1 Introduction ..................................................................................81
3.2 Chemical Degradation ..................................................................87
3.2.1 Air Pollution ....................................................................87
3.2.2 Black Crusts .....................................................................92
3.2.3 Oxalate Patina .................................................................94
3.2.4 Leaching of Stones by Water and Acids ............................95
3.3 Processes of Physical Decay ..........................................................97
3.3.1 Salt Crystallisation ...........................................................97
3.3.2 Rising Damp ..................................................................100
3.3.3 Freeze-Thaw Cycles .......................................................101
3.3.4 Physical-mechanical Stress .............................................102
3.4 Biodeterioration ..........................................................................102
3.4.1 Bacteria and Bacterial Biodeterioration ..........................104
3.4.2 Fungi and Fungal Biodeterioration .................................105
3.4.3 Lichens and Lichenic Biodeterioration ...........................105
3.4.4 Biodeterioration by Higher Plants ..................................107
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Contents
4 Conservation of Stone Artworks ............................................................113
4.1 Introduction ................................................................................113
4.2 Artworks Conservation: General Highlights ...............................114
4.3 Preventive Conservation .............................................................116
4.4 Responsible use of Surface Coatings and Polymer-based
Consolidants ...............................................................................117
5 Diagnostic Approaches: Methods of Evaluation .....................................121
5.1 Science and Conservation ...........................................................121
5.2 In Situ Decay Assessment ............................................................123
5.2.1 Ultrasound .....................................................................125
5.2.2 Infrared Thermography .................................................125
5.2.3 Surface Methods ............................................................126
5.2.4 Other Methods ..............................................................127
5.3 Instrumental Laboratory-based Methods used for Decay
Assessment ..................................................................................128
5.3.1 X-Ray Thomography .....................................................129
5.3.2 Magnetic Resonance Imaging ........................................131
5.4 Laboratory Tests for Assessment of Consolidating and
Protective Products .....................................................................134
5.5 International Standards ...............................................................135
5.5.1 Standard Test Methods ..................................................135
5.6 Long-term Performance ..............................................................145
5.7 Identification of Biodeteriogens and their Activity.......................146
5.8 Instrumental Methods for the Evaluation of Characteristics
of Stone and Polymers ................................................................147
5.8.1 Raman and Infrared Spectroscopy .................................147
5.8.2 Nuclear Magnetic Resonance Spectroscopy ...................148
5.8.3 X-Ray Fluorescence .......................................................150
5.8.4 Contact Angle ................................................................150
5.8.5 Differential Scanning Calorimetry ..................................151
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