DIAGNOSIS OF BUILDING FAILURES

IN POROUS MATERIALS

Dr Donald Ellsmore

Director, Donald Ellsmore Pty Ltd

Convenor, Australasia Chapter

Association for Preservation Technology

The predominant materials of the built

form of the World Heritage listed sites

of Melaka and George Town Penang,

and many other parts of Asia, are

porous.

Porous materials are stone, bricks,

plasters, wood, clay roofing tiles,

ceramic tiles and some decorative

finishes.

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All porous materials are affected in

one way or another by water, which

is often an agent of decay.

Water dissolves and washes away

surfaces, it causes wood to expand

and it causes salts to move around

in masonry materials. It is essential

for living organisms, including

vegetation and mould.

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Water is a dangerous enemy of poorly maintained buildings.

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In well maintained buildings water is managed for the benefit of the occupants

and the fabric of the buildings.

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MAKING DECISIONS ABOUT BUILDINGS

• Understand the significance of the building and place –

understand what is most important about it and what should be

conserved.

• Protect authenticity – ensure that all actions are based on an

understanding of authenticity.

• Take all necessary steps to address the issues of greatest

concern – secure the fabric, ensure that use is appropriate for

the place and do not remove significant material or introduce

incompatible new material unless there is no alternative.

• Undertake appropriate maintenance and avoid damage.

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When MAKING DECISIONS about HERITAGE BUILDINGS

several important matters must be considered.

Significance is a function of history, authenticity, social and community esteem.

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The inscription of places on the World

Heritage List is based on Universal

Significance – a concept which

embraces tangible and intangible

values.

Tangible values include building

fabric, which should always maintain

its authenticity in order to preserve its

inherent values.

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The ways of doing things in SE

Asia often differs from Western

ways.

Heritage practice in the East is now

guided by principles that derive

largely from Western practice

though recognising Eastern values

that are inherent in and fundamental

to significance and authenticity of

heritage places.

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In Western society a concern for the

conservation the authentic fabric of

ancient buildings was raised in the

19th Century by William Morris,

John Ruskin and others. They

established the Society for the

Protection of Ancient Buildings

(SPAB) known as ‘Anti-Scrape’

because of its opposition to

aggressive restoration. The SPAB

approach informs or modern

practices.

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The Australia ICOMOS

Charter for Places on

Cultural Significance,

1979 (revised 1999) –

developed from the Venice

Charter , 1964.

Principles for the

Conservation of Heritage

Sites in China, 2000.

Hoi An Protocols for Best

Conservation Practice in

ASIA, 2009.

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In the South East Asian context

authenticity can have a different meaning

from the Western concept.

It may involve continuing customs and

practices.

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Authenticity of intangible traditions

does not preclude the use in

conservation of traditional

technologies or new science. Both

may be applied to obtain good

outcomes.

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WHY CONSERVE AUTHENTIC FABRIC?

Authentic fabric is physical evidence of history – it provides access to truth.

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Authentic fabric can provide a window through which to view history.

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In SE Asia there are many pressures

on heritage places. There is

pressure to obtain economic

benefits, accommodate tourists,

maintain social cohesion and also to

protect places of value to local

communities and to the World

community.

There are issues that are common to

many places.

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Tourism impacts on conservation.

Tourism impacts on clarity of

purpose?

Tourists can overwhelm heritage

places?

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Good conservation outcomes can be

obtained with careful planning and

the application of heritage

guidelines.

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Poor conservation outcomes arise

through neglect and lack of

attention to basic maintenance or

through the application of

inappropriate methods and

materials.

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When it comes to undertaking

heritage works, the important

matters are protection of

significance and authenticity, and

the use of appropriate methods and

materials, based on a correct

understanding of materials

properties.

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It is tempting to suggest that a good

coat of impervious paint will solve all

problems with porous buildings but the

reality is somewhat different. In fact it

is found that the use of non-porous

paints will often hasten the decay of

traditional buildings made of porous

materials. The care of heritage

buildings requires a clear

understanding of their significance and

their conservation needs.

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Technologies for fabric

conservation are expanding with

scientific research and by drawing

from continuing traditional

pactices.

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Traditional practices are often the best for use in SE Asian countries.

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In other places the loss of traditional skills causes a greater focus on new technologies.

BRICKS AND MORTAR

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Brickwork is normally made with

moderately hard bricks laid in

relatively soft mortar. The role of the

mortar is to bed the bricks and

distribute the loads. It is NOT to stick

the bricks together.

Brickwork deteriorates when it is

exposed to salts and damp and when

hard mortars are used with soft bricks.

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PLASTERS

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Traditional plasters are made with

sand and lime and applied in layers.

The top surface layer is usually harder

and smoother than the underlying

layers. Its purpose is to protect and

decorate.

Plasters should not be allowed to

remain damp or they will deteriorate

due to salt activity and fungal decay.

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In SE Asia there are many fine

examples of stucco illustrating early

cultures including Kmer culture. There

is little difference between the ancient

plasters and those used in more recent

times prior to the introduction of

Portland cement. Modern cement

plasters are different to traditional

plasters and incompatible with soft

bricks and stone.

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Traditional lime plasters should not be replaced with modern Portland cement.

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WOOD

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Wood is a hygroscopic material that

expands when the moisture content

increases, and shrinks when the moisture

content decreases.

Changes in atmospheric moisture content

is one of the principal causes of

deterioration of wood.

The other causes of deterioration are

weathering, or the combined effects of

water and sunlight, and biological decay

in the form on insect attack and fungal

decay.

The constant expansion and

contraction of wood, with changes in

relative humidity, causes the failures

including coating failures, splitting and

in some instances collapse of wooden

structures.

Exposure of wood to sunlight causes

wood to weather and, ultimately, to

deteriorate.

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Fungal decay in wood.

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CONCRETE, IRON AND STEEL

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Most concrete is

reinforced with iron or

steel.

Reinforced concrete is

now used in most large

new structures,

Iron and steel corrode

when exposed to water

and air.

Concrete is relatively

stable but it readily

deteriorates when steel

reinforcement corrodes.

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Causes of concrete deterioration

include:

• Aggregate expansion

• Corrosion of steel reinforcement

• Chemical damage

• Carbonation

• Chlorides

• Sulphates

• Leaching

• Decalcification

• Sea water

• Bacterial corrosion

• Thermal damage

• Radiation damage

• Physical damage

• Human intervention

The rapid growth of urban centres ,

particularly in S E Asia, has

brought about a looming crisis with

reinforced concrete structures

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Concrete failure due to corrosion

Concrete surface failure – man made

Concrete failure due to delamination of steel

Concrete surface failure - natural

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Reaction between alkali and aggregate – is just one form of failure with serious

consequences for some concrete structures.

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PAINTS AND FINISHES

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Villa in Phra Nakhon, Bangkok Old Shophouse in Tha Pae, Chiang

Mai

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Traditional yellow colouring on

French colonial villa in Champasak,

Laos

Traditional yellow colouring on

stucco of French colonial era

temple in Champasak, Laos

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Modern yellow colouring on 1930s

concrete History Museum in Hanoi

designed by Hebrard

Modern interpretation of traditional yellow

colouring in George Town, Penang

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The traditional yellow colouring which

has been used for centuries is inexpensive

and simple to make and easy to apply. It

lasts longer than modern coatings and is

far better for the conservation of porous

masonry structures

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LEARNING AND DOING

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The next generation will benefit from the proper care of our heritage places.

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