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Building and Environment 42 (2007) 1329–1334
www.elsevier.com/locate/buildenv
Life cycle, sustainability and the transcendent quality
of building materials
Eduardo Peris Mora
Departamento de Ingenierı´a de la Construccion y Proyectos de Ingenierı´a Civil, Valencia Polytechnic University, Spain
Received 4 October 2004; received in revised form 27 September 2005; accepted 9 November 2005
Abstract
This paper explores the relationship between the life cycle of engineering works and their sustainable and transcendent qualities, and
considers the possibility of creating durable works with ephemeral materials. This paper also studies the impact of urban growth and its
infrastructures on the environment through the consumption of raw materials and energy. City metabolism is one of the main causes of
environmental deterioration, and present-day tendencies make it foreseeable that both urban and infrastructure development shall
continue to increase. Although the expression ‘‘sustainable construction’’ is being used more and more, it is necessary to distinguish
between the sustainability of the construction activity and the sustainability of works constructed. Both the materials and technologies
used since ancient times have allowed many past works to have lasted thousands of years. Some were made out of permanent materials
such as stone while others were made out of more ephemeral materials such as adobe bricks or cob walls. Structures built with Roman
cement are still standing after 20 centuries. The overall durability of built structures depends on the durability of their materials.
Transcendent construction was made possible either using permanent materials or more ephemeral materials, providing the project had
taken the need for maintenance into consideration. The development of building works in a modular fashion makes the repairing action
of modifying materials or parts of works possible without destroying its basic structure. With our present-day knowledge, plain concrete
permits to create transcendent structures that could last several centuries.
r 2005 Elsevier Ltd. All rights reserved.
Keywords: Building materials; Construction; Maintenance; Durability; Sustainability; Life cycle
1. Introduction
There is plenty of scientific literature on durability, the
life cycle and sustainability associated to building materials. Adding a transcendental dimension is almost compulsory for many works which, through their own vocation,
have been designed with the purpose of extending their
durability to greater scales than a single human generation.
All human groups and their ways of building are
determined by their geographical and historical environment. In this sense, geography, anthropology, the science
of materials and their relations with building, can allow us
to understand the built environment better. Engineers,
architects, experimental scientists and other specialists,
share the interest to analyze the environment form different
point of view. Materials and environmental engineers are
E-mail address: [email protected].
0360-1323/$ - see front matter r 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.buildenv.2005.11.004
interested on the effects of building materials on sustainability. Eminent ecologist, professor Margalef describes an
inexplicable phenomenon: in nature: Natural ecosystems
(excluding mankind) evolve in such a way that they
culminate in an accumulation of wood in their most
developed stages whereas mankind, especially during the
last half century, follows an inexplicable process of
accumulating concrete [1]. The Romans built concrete
works with a cement chemically similar to that we use
today, leaving behind works that have transcended
temporarily and intellectually over many generations [2].
The Roman roads that still exist—some of them beneath
our modern-day highways—were at the time the most
efficient way to maintain good communication within the
Roman empire, and which have given rise to an expression
that is common in several European languages, which is
more or less expressed by ‘‘all roads lead to Rome’’.
However, this expression would not be totally justified if
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we do not think of more ephemeral roads (‘‘Walker, there
is no path, rather the wakes on the sea’’, as written by the
Spanish poet, Machado [3]). The Romans maintained a
close relationship with their environment using environmental factors such as volcanic craters as harbours and
natural materials such volcanic ash to develop their
building technology and society. Ports and roadways, as
well as irrigation systems and aqueducts built by Romans
and older cultures, constitute a heritage of works which we
should assess as ‘‘transcendent structures’’ because they
have aesthetic values are durable, having remained
generation after generation.
The increase of the world’s population propitiates the
construction of more large, expensive infrastructures which
are, supposedly, built to last. City metabolism is responsible for the greatest consumptions of materials, energy and
water [4]. The world population is expected to increase by
almost 2 thousand million people between the years 2000
and 2030, and almost all these inhabitants shall live in
African, Asian and Latin American cities [5]. The cities
belonging to the ‘‘Industrial North’’ were the demographic
centre of attention around the year 1900. In the year 2000
however, only Tokyo, New York and Los Angeles are
featured on the list of the ten largest world populations.
The demographers expect the city of Los Angeles to be
exceeded by fast growing cities such as Lagos, Doha,
Karachi and Jakarta by the year 2015. The number of
inhabitants presently living in large urban areas already
reaches the figure of 3000 million; between 2000 and 2015
this figure shall be increased by 972 million; every 5 years
the urban population in Africa, Latin America and Asia
doubles in number. However, it is estimated that more than
60% of this population shall live under indescribable living
conditions.
An increase in population is coupled to a raise in
atmospheric emissions and these adversely affect the
durability of building materials [6]. When the total atmospheric emissions of the five substances that we use to
measure pollution are estimated (CO, NOx, SO2, HC and
particles), it is surprising to find that natural emissions
easily exceed the collective anthropogenic emissions.
However atmospheric pollution problems, as far as these
substances are concerned, originate to a great extent from
spatial and temporary concentrations rather than from the
total quantity released [7], and this concentration is mainly
produced in urban atmospheres. Other global environmental problems are also found in the cities: From vehicle
exhaust pipes which heat the atmosphere, to the demand of
wood for building purposes that deforests the land and is a
threat to biodiversity, and a municipal thirst that leads to
massive water consumption. Cities are therefore where the
greatest amount of world resources are consumed.
Approximately 78% of carbon emissions come from fossil
fuels that are burnt to make cement, and 76% of industrial
wood worldwide is used in large metropolitan areas.
Furthermore, 60% of the water that runs through pipelines
is consumed in cities [5].
Nonetheless, cities constitute a driving power for the
economical and social development of most countries;
cities generate 55% of the GNP (Gross National Product)
in those countries with weaker economies, 73% of the
GNP in countries with an average development, and 85%
in the more developed countries. It is this economic growth
that ensures that communities invest in infrastructures and
may providing general services to the population [8].
According to the above it is logical to think that, in the
immediate future, urban growth and its infrastructures will
continue to produce maximum impact on the natural
environment through the use of materials and the
consumption of raw materials and energy. The number of
construction works shall progressively increase however,
these shall be undertaken by attempting to achieve the
paradigm of sustainability, demanding an increasing
durability of what is being built in order to minimize
environmental impact.
2. Life cycle and environmental impact
ISO-EN-UNE- 14.040 regulation, defines life cycle as the
‘‘consecutive and interrelated stages of a product system,
from the acquisition of raw materials or the generation of
natural resources until its final elimination’’. Life cycle is
closely related to environmental impact: According to the
aforementioned standard, the life cycle assessment (LCA)
is the ‘‘collection and assessment of the inputs and outputs of
any potential environmental impacts caused by the product
system throughout its life cycle’’. This allows us to learn
about the environmental effects of a certain work or
product. The environmental effects derived from the
construction of a given structure, its life time, reuse and
demolition should all be taken into account within the
LCA; the possibility of reusing by either recycling or
recovering materials or energy should also be taken into
account. An important aspect that ought to be considered
in the LCA of works is preventive maintenance. In the
construction industry continuous necessary maintenance is
frequently substituted by sporadic remedial actions involving repair, restoration or reconstruction which target
deteriorations threatening the structure or its services.
LCA methodology, which has been applied for some
time to assess the environmental impact of industrial
products (ISO 14.040), also makes sense in construction
and may be equally applied to civil works and architecture
[9–11]. The environmental impact of engineering works
must be assessed starting ‘‘from their birthplace’’ by
considering concepts such as the Environmental Impact
Assessment (EIA) of the overall project (Directive 85/337/
CEE) [12] and by also including issues such as preliminary
strategic assessments (Directive 97/11/CE and Directive
2001/42/CE) [13,14] of the use of the ground involved,
alteration to the landscape, choice of materials and their
impact, etc. The LCA must study the service life cycle of a
structure as well as any environmental effects derived from
maintenance tasks and, once the service life has been
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exhausted, the environmental impact of its abandonment
or demolition. Following demolition, materials may be
totally or partially reused if the appropriate demolition
techniques are applied [15]. Here lies one of the main keys
to sustainability, since materials management (reduction,
reuse, recovery etc.) releases materials that were ‘‘temporary’’ part of the work. Materials that can be recovered in
the demolition process confer to the engineering work the
property of sustainability. The possible irreversibility of
environmental impacts must also be contemplated within
the LCA by assessing, when appropriate, the environment’s capacity for recovering. Neither should the LCA
nor should the person who drafts the project forget the
effort required a preventive maintenance which may
commit future generations with the transcendent quality
of a given structure. Finally, LCA methodology should
also take into account preventive maintenance programmes
which will require an effort and commitment by future
generations.
3. Sustainability
As a starting point, the concept of sustainability has an
economical interpretation. A business may be sustainably
managed when it allows exploitation over indefinitely
prolonged time. By following the example proposed by
González Bernáldez [16], we can state that a mining
exploitation is conceptually unsustainable beyond the
exhaustion of a given deposit. In contrast, wood may be
sustainable exploited by calculating how much wood is
produced per year, and withdrawing only a certain
quantity (same amount as that being produced at the
most). Alternatively, wood could be exploited with a
‘‘mining technology’’, that is unsustainably indiscriminately withdrawing the existing wood with market-dependent criteria therefore devastating the plantation.
The sustainability concept has also been applied to
characterize a type of development: ‘‘sustainable development’’. A prospective study produced by the Massachusetts
Institute of Technology (MIT) for the Rome Club at the
end of the 60s (The Limits of Development) [17] demonstrated the exhaustion of raw materials and the incapacity
of the terrestrial ecosystem to recover from damages
caused by the huge impacts of generating technologies,
and announced a critical situation which should have been
confronted a considerable length of time ago. Four decades
later, a second report produced by the same Institute
studied the worldwide environmental deterioration that
had occurred during the ellapsed time, regrettably confirming the most pessimistic predictions.
Finally, a new sustainable development paradigm was
adopted: ‘‘sustainable growth’’. There are many connotations to this expression, however, it constitutes an utopic
objective rather than a true action methodology as
development and growth are substantially different.
Sustainability applied to construction, can be interpreted
in different ways [18]. Sustainable construction can refer
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either to the building process or, alternatively, to the builtobject. It is difficult to establish an analogy in construction
with the sustainable exploitation of timber aforementioned.
In fact, construction involves the consumption of raw
materials and energy and the use of land upon which the
structure is established. In absolute terms, sustainability
would only be possible when construction uses renewable
energy resources, and renewable materials or materials
recycled from construction waste. Furthermore, to comply
with sustainability, the land should not be irreversibly
mortaged. Since this ideal situation is an utopia, it shall be
necessary to interpret sustainability in construction as
other authors do, that is as an approximation to the ideal
situation above. The concept ‘‘sustainable construction’’
has been used [19,20] to characterize construction that
includes environmental criteria in the project concept, in the
way of building, maintaining and, when the time comes, of
demolishing the works. Sustainable construction may allow
the construction industry to become a sustainable development.
The use of waste materials is one of the ways of
integrating a sustainable approaching to the construction
industry. Metha [21] quotes Hawken stating that only 6%
out of the total volume of raw materials used by man—
around 500,000 million tons each year—become usable
products. The remnant returns to nature in the form of
dangerous or inconvenient waste products which harm the
environment. The construction industry is responsible for
7% of global CO2 emissions. To a great extent these are
due to the production of concrete (approximately 1 kg of
CO2 for each kg of cement produced), and it is estimated
that 2000 million tons a year of this material is to be
consumed during this decade. According to Metha, the
most efficient way for construction to approach sustainability is to first reuse waste products from other industrial
activities as well as to improve the durability of the works
to last. Both ways may be linked together as, for example,
the use of waste materials as fly ashes and iron slags as
substitutes for cement in concrete production increases
concrete durability simultaneously fulfilling both purposes.
The World Board of Commerce for Sustainable Development (WBCSD) has promoted an initiative to encourage
cement sustainability. This involves the World Wildlife
Foundation along with ten cement factories, including
Lafargue, Holcim, Italcementi, Cemex, Cimpor and RCM.
This initiative aims to improve environmental management
of cement production, in order to reduce the greenhouse
effect and volatile emissions as well the implementation of
specific sustainability management indicators for this
industrial activity [22].
The utilization of waste products in construction not
only constitutes a rational response to improve environmental management of industries, but it is also a necessity,
and as such it has been implemented by most of the
construction industry in countries such as Holland and
Japan, which virtually lack raw materials [23]. Construction waste products can be re-used for economic, rather
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than for moral reasons. For example, Germany used
rubble of cities devastated in the world war for new
building and the recycling of construction rubble for new
buildings also took place in Barcelona with the works built
in 1992 for the Olympic Games City, relevant case studies
can be found in Vazquez [24] and Gómez Soberón [25].
4. Durability and transcendence
Durability is the characteristic of those objects or
materials that maintain their properties over time. Durability ends when the object or material has to be replaced
or, should it be the case, when the use that the material
had, or the work it forms part of, is brought to an end.
A durable material or object is useful for longer. As far as
construction is concerned, if we were to increase the
durability of concrete works from 50 to 500 years, factor 10
would be a measure of the reduction of the environmental
impact that these works would have (20) as it would not be
necessary to repeat the initial production impact for the
work to be reconstructed.
Construction quality is a measure of how a particular
work meets the requirements demanded by the building
project. In contrast with sustainability, durability can be
quantified. Durability is an indicator which informs of the
extent to which a material maintains its original requirements over time. The greater the material durability, the
lower the time and resources required to maintain it
[26,27].
Concrete structures are built to provide a service during
a limited time period and, in some cases, the need for
maintenance are foreseen. In the case of some assets, such
as automobiles and electronic computers it is generally
assumed that, throughout their service life, they shall
receive proper maintenance. However, in the construction
industry, this is not the case and buildings are conceived
not catering for maintenance. However, there are exceptions. Hognestad [28] describes a particular example in
which the service life of a construction had to be especially
guaranteed since it happened to be an oil rig placed in the
North Sea. Here, calculations were made to foresee the
magnitude of progressive materials deterioration and
considered impossible to cater for. A further exception is
Radomski [29], who refers to maintenance interventions on
a high number of structures (mainly bridges) in Poland.
However, when referring to maintenance interventions,
Randoski’s examples involved repair rather than maintenance work. Finally, in relation to durability, it should be
noted that certain building technologies such as modular
construction would facilitate partial replacement of defective materials in engineering works enhancing the durability of the construction. For instance, the artificial vault
at the Abbu Simbel temple in Egypt has been built with
reinforced concrete. This material will probably offer a
long service life although not in the extent that the
monument requires. However, it has been undertaken as
a separate module so that, in the event of weathering, this
will not adversely affect the overall durability of the
original structure.
Whether it is for functional or aesthetic reasons, some
works are conceived with a transcendent quality. Occasionally the architect or the civil engineer handles projects
that intrinsically possess a transcendent vocation, that is
their service life is to last for several generations. These
works were deliberately conceived and signed by their
author or client to last for posterity. Funerary and religious
monuments feature among the eldest constructions on the
planet which, by their own nature, were conceived to
remain for ‘‘eternal’’ use. Monoliths, mastabas and
pyramids testify our ancestor’s desire of building to last.
In contrast, industrial structures and infrastructures
including silos, warehouses or canalizations which almost
certainly were not built to last have however reached our
time.
Our culture is an urban phenomenon. In the shaping of
mankind’s way of thinking, with its education and ethics,
the urban environment constitutes an interactive framework. The personal history of each man and human group
has—in most populations—been built in an urban environment therefore the works and infrastructures that we see
in which we live, determine our way of thinking. However,
the opposite is also evident as the planning and urbanism
of cities and infrastructures is determined by the way of
thinking of the people living/using them. For example,
European medieval cities with their squares, markets and
hamlets have a different character to that of towns
arranged in a planned colonization processes. The urban
growth of Mediterranean cities reminds to that of a living
organism, whereas a more rational form, almost crystalline, inorganic, was often adapted by military cartographers in the colonies of the new world.
An engineer or architect designs works to provide
accommodation or solutions to infrastructure problems.
Sometimes building works are everlasting because of their
nature, becoming part of the heritage of a generation and
those to come. Many of the constructions we consider
heritage today were designed with both transcendent and
functional vocations. Roadways, aqueducts or funerary
monuments, were designed to provide a service for years.
Materials successfully used in functional construction
may not last long enough to be used in transcendental
works. For example, concrete is not expected to last for
more than one hundred years while reinforced concrete has
a limited life cycle due to deterioration through thermal
cracking, drying and icing/thawing effects, carbonation/
corrosion of reinforcements, environmental chemical attacks, alkali–silica reactions or mechanical corrosion of
various kinds. Many concrete constructions aged between
50 and 90 years exist at present worldwide [30]. However,
Mehta and Langley [31] present an interesting exception.
This is the case of a Hindu temple built in Kauai, Hawaii,
on a plain, non-reinforced 380 m3 concrete foundation,
where a minimum durability of 1000 years was requested
by contract.
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Certain historic constructions that constitute our heritage were built with modest materials which were not
expected to last, however, these allowed for simple repair
work to be undertaken having survived to our present day.
Examples built in adobe bricks and cob include the
constructions of Agar-Guf in the Middle East (14th
Century B.C.) [32] or the walls that surround the Temple
of Horus at Idfu (in Egypt) together with others built with
a primitive concrete including the Roman Coliseum (2nd
Century A.D.) or Saint Sophia Cathedral, also known
as the Church of the Holy Wisdom, at Istanbul (Turkey)
(4th Century A.D.).
Finally, the transcendence of an infrastructure can be
enhanced by increasing the durability of its materials [33].
For example, the durability of concrete can be increased by
following certain procedures such as reducing the amount
of water used for mixing or replacing cement with ashes
[34–36] procedures already used in antiquity. Furthermore
the Romans applied exhausting but effective ways of
placing concrete by means of compacting to ram down the
mixture, a procedure that has been invariably used for
thousands of years in the building of cob walls where clay
is used as a conglomerate.
5. Conclusions
Modern-day construction poses demands on engineers
and architects which can lead to the future deterioration of
built structures. This can compromise the cultural,
scientific and technological image of a generation. For
example, according to our present knowledge, very slender
concrete works with reinforced sections of clad steel posses
a limited durability and should allow for repair work to be
undertaken in future. Likewise, the use of special materials
which offer no historical durability assurance such as white
cement used in heavily reinforced plain concrete, or
titanium roofs in polluted atmospheres may also lead to
deterioration. This can be avoided if relevant investigation
or scientific knowledge available is included within the
building project. Sustainability should also be integrated in
the building project under the consideration of its LCA. In
absolute terms, sustainability would only be possible when
construction uses renewable energy resources, and renewable materials or materials recycled from construction
waste. To comply with sustainability, the land should not
be irreversibly mortgaged.
Transcendent construction requires catering for durability. However, it is necessary to consider two concepts
separately: the durability of the engineering works and the
durability of the materials they are built with. Certain
materials can be considered as permanent if they prove to
be indefinitely stable under average aggressive environmental conditions, as is the case with certain types of
natural stone. Works built with these stone types can be of
a transcendent nature. In contrast, constructions made out
of non-permanent materials can also be permanent when
these materials allow for maintenance and/or repair work
1333
which, when conducted, will allow conservation of the
original structure. In this context, when using materials
with a limited durability, to undertake modular construction should be considered.
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