About AAC - Why You
Should Build with Autoclaved Aerated Concrete
Autoclaved Aerated Concrete (AAC) is a
building material which consists of various sized elements
that form a complete building system. In most cases, every
portion of the structural and insulation requirements of
a building are satisfied with the one material. The elimination
of a number of other materials, and the fact that AAC is
an inherently "green" building system result in
a "healthier" building. Low energy required in
production, low raw material consumption, ease of use in
construction, high energy efficiency, better indoor air
quality, and recyclability add up to make AAC a very environmentally
friendly building material and system.
Also on this page;
The Advantages
of AAC
Ecolite AAC Product Descriptions
Introduction
Autoclaved aerated concrete (AAC) was
developed in Europe in 1923. Commercial production of
the material began in 1930. In 1995, more than 31 million
cubic meters were produced by over 50 factories worldwide.
More than 75 million cubic meters were produced worldwide
by over 100 factories in 2004. AAC is used in a wide range
of building construction with residential, commercial
and industrial buildings being common applications. The
system consists of small masonry-like units, larger "jumbo"
units, panels, and a variety of specially manufactured
shapes and pre-assembled wall sections.
Several important factors contribute
to AAC's worldwide acceptance. It is a versatile, easy
to use, durable, and energy efficient system. AAC is the
only viable, single component structural insulation system
available. The walls, floors and roof of a building can
be constructed with the system. Using one material to
build the entire structural and insulation part of a building
offers many advantages, allowing excellent design flexibility,
quick construction and reduced waste.
AAC is well known as an environmentally
friendly construction material. Compared to the energy
consumed in production of many other basic building materials,
only a fraction is required to produce AAC. Raw material
consumption is very low for the amount of finished product
produced. In the manufacturing process, no pollutants
or toxic by-products are produced. AAC is also completely
recyclable.
Due to AAC's excellent insulation qualities,
energy consumption for the heating and cooling of buildings
is greatly reduced compared to most conventional wall
and roof systems. In the finished structure, no pollutants
or toxic substances are released that could affect indoor
air quality, even in the event of fire.
Raw Materials
AAC consists of basic materials that
are widely available. These include sand, cement, lime,
gypsum, water, and an expansion agent. Silica sand, the
raw material used in the greatest volume in AAC, is one
of the world's most abundant natural resources. The finished
product is up to five times the volume of the raw materials
used, with an air content of between 70% to 80% (depending
on the required strength and density.) Due to this large
increase in volume, AAC is very resource efficient. The
following chart demonstrates the volumes obtainable from
one cubic metre of raw materials for AAC and various other
common building materials. 
Production
The ingredients of AAC are mixed to
form a slurry that is poured into large metal molds. The
reaction between the expansion agent and other components
used in AAC causes the slurry to expand (rise) in the
mold and form a "cake." After several hours,
the mould is stripped away and the "cake" is
wire-cut into aerated concrete elements of high dimensional
accuracy. These elements are then put into an autoclave
(a vessel in which they are steam cured under pressure.)
After autoclaving, AAC can be shipped and used immediately.
The production process emits no pollutants
and creates no toxic waste products. All waste produced
during manufacturing is reused. Production of AAC requires
relatively little energy for the volume of material produced.
The following chart compares production energy consumption
for AAC to some other common building materials.
Use in Construction
Ease of use of a building material is
important in many ways. Construction time, manpower, waste,
and energy consumed by equipment used during construction
are affected. Large, precisely dimensioned elements of
AAC allow rapid construction. Their greater dimensional
accuracy requires less on-site adjustment. The combination
of large size and dimensional accuracy allows greatly
increased productivity. Due to the light weight of AAC,
reduced equipment demands are realized. This allows a
reduction of pollutants by emissions and power usage of
equipment during construction. As an example, the structure
of a recently constructed seven storey hotel in Atlanta
was completed with much less equipment, manpower, and
waste.
Construction waste continues to be a
serious problem for builders. Before completion of a building
project, waste is either burned, buried, recycled, or
shipped to a landfill. Many areas do not allow burying
or burning due to the environmental problems created.
A very small amount of recycling is currently possible
due to the lack of infrastructure to support it. Landfills
are becoming the more common method of disposal, which
presents other environmental problems. Two features of
AAC help to greatly reduce waste. First, since it is both
a structural and an insulation material, it simplifies
construction, eliminating a number of different materials
and their associated waste. Second, due to the ease of
workability, and dimensional accuracy, very little waste
occurs during construction. The woodworking properties
of AAC allow even cut pieces to typically be reused.
The Finished Building
An AAC building can be very cost effective.
In the U.S., first costs are generally only 1% to 5% higher.
Operating cost savings for the building owner prove to
be substantial, with life cycle break-even within a relatively
short period of time. The AAC building owner sees a significant
reduction of maintenance, insurance and energy (heating
and cooling) costs, as well as an increase in overall
comfort and safety.
Conclusion
As a construction system, AAC provides
significant environmental and other benefits for the builder
and the building owner. The short- and long-term effect
of using AAC compared to many other materials results
in lower energy consumption, reduced operating costs,
greater safety and comfort, and a healthier and more trouble-free
building. These features provide a better investment for
the building owner, and for our environment.
The advantages of using Autoclaved Aerated
Concrete.
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Energy Efficient |
High energy efficiency in a building
is desirable for many reasons. By reducing heating and
cooling requirements, lower operating costs and equipment
sizes are achieved. Better temperature and humidity control
will provide greater comfort for the building occupants.
The reduced energy requirement of a building also helps
conserve natural resources such as oil, coal, natural
gas, etc., thereby reducing emission of pollutants into
the atmosphere. Both the reduction in energy usage and
pollutants should be considered over the total useful
life of the building.
It is widely recognized that AAC buildings are very energy
efficient. This efficiency is due to a combination of
high R-value, thermal mass and air-tightness. AAC is the
only product currently available that meets Germany's
stringent energy codes without added insulation. It is
well documented that the R-value of a mass product need
not be as high as that of light frame construction, to
perform thermally efficient. A recent study in the U.S.
shows that an 20cm AAC wall performs much better than
a conventional wood stud wall system with R-30 insulation.
The manufacturing process creates millions of tiny air
cells that provide excellent thermal resistance. This
thermal resistance combined with the benefits of thermal
mass inertia, whole wall coverage and low air infiltration
will, in many jurisdictions, eliminate the need for additional
insulation.
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Fire Resistant |
A danger of many conventional materials
is that of toxic fumes produced when they burn. The same
properties that make AAC thermally efficient also provide
exceptional fire resistance characteristics. AAC is an
inorganic material that does not burn. The melting point
of AAC is over 2900~F (1600~C), more than twice the typical
temperature in a building fire of 1200~F (650~C.) An 20cm
AAC exterior wall easily exceeds a four hour ASTM E-119
fire rating, while a typical AAC floor system or 10cm
interior wall easily exceeds a two hour rating.
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Environmentally Friendly |
AAC is well known as an environmentally
friendly construction material. The production of AAC
requires only a fraction of the energy compared to other
materials. The manufacturing process emits no pollutants
and creates no by-products or toxic waste products.
AAC is manufactured from common and abundant natural raw
materials. The finished product is up to five times the
volume of the raw materials used, making it extremely
resource-efficient and environmentally friendly. Manufacturing
waste is recycled into the raw material mixing process.
AAC is recyclable, inert, nontoxic. AAC is not a source
of chemical off-gassing that can cause indoor air pollution
and illnesses.
In the U.S., it is estimated that 80 to 90 percent of
an average person's time is spent indoors; at home, work
and in other buildings. A number of issues must be addressed
concerning these buildings and their environmental friendliness.
Indoor air quality, safety, comfort, energy consumption
and waste, noise, and in general how "healthy"
a building is, are some of the more important issues.
It is widely known that some of the poorest quality air
we breathe is in our homes and the buildings we work in.
Many materials used in construction contain toxic substances
and off-gas. It is not unusual for construction materials
to pollute indoor air with formaldehydes, benzyne, arsenics,
and other chemicals that are classified as hazardous to
human health. Even fibreglass insulation, a commonly used
material, is classified as a carcinogen by the U.S. Government.
AAC is an inorganic material that contains no toxic substances.
It does not slowly decompose and off-gas. Since AAC is
both a structural and insulation material, it allows the
elimination of other materials that can contribute to
poor indoor air quality. With the mineral based plaster
coatings commonly used on the interior of AAC, complete
elimination of toxic materials from the walls is possible.
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Strong |
Dimensional accuracy and compressive
strength allow AAC to be used in many load bearing applications,
whether it is a large, small or tall job. Installed using
thin bed mortar, the resulting wall functions as a monolithic
structure.
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Durable |
Durability, and its environmental impact, is an important
factor when considering use of a building material. A
structure that does not need major repairs and renovation
every twenty years or so (as many wood products require)
can save money, inconvenience, energy and other resources.
This is of tremendous advantage to the building owner,
creating a better investment and value up-front and long-term.
AAC has proven to be a very durable material. There are
numerous structures worldwide, many over 60 years old,
in excellent condition. AAC will not rot, warp, rust,
corrode, or otherwise decompose. AAC provides a very low
maintenance building, saving considerable time and money
in upkeep over the life of the building. Although damage
to a AAC wall is unlikely, repair is simple using a AAC
repair mortar.
The durability of finishes, both exterior and interior,
plays an important role environmentally. With AAC, any
number of interior and exterior coatings or applications
are possible. More common coatings, such as a stucco type
finish, along with interior plaster, aid in creating a
more environmentally friendly structure. The stucco type
finish used on AAC is very durable and requires little
maintenance. These finishes can be integrally coloured
with mineral pigments, eliminating the need for frequent
painting. Interior plaster applied to AAC is durable,
yet easy to repair. Veneered plaster can be left unpainted,
providing a pleasing appearance.
AAC will not rot, warp, rust, corrode, or otherwise decompose.
Termites and other pests do not eat it. AAC will not burn.
The millions of tiny cells in AAC cushion buildings from
major force, preventing progressive collapse. AAC has
withstood earthquakes in Japan, the frigid temperatures
of northern Europe, the harsh salt air of the French Riveria,
and the hillside fires of San Fransisco.
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Lightweight |
Weighing approximately 20% the weight
of normal concrete. AAC provides significant benefits
where weight is a concern in building design. AAC is ideal
for renovations. The product provides beneficial installer
safety and fatigue features.
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Workable |
AAC can be easily cut and shaped using
standard construction tools. Window trim and decorative
features can easily be created on the job site.
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Dimensionally Accurate |
State-of-the-art cutting equipment produces
blocks that are dimensionally accurate to within 3 mm,
making AAC easy to install.
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Low Maintenance |
AAC is an inorganic material impervious to rot, insects, and
other pests. Since the walls are solid, it is not possible
for insects to inhabit and breed in them as in most wall
systems. Without concern of termites and other insects
damaging or inhabiting the AAC portion of the structure,
chemical treatments can be reduced or eliminated. This
prevents the need of putting these chemicals into the
ground, or the indoor air, with their associated environmental
and health threats.
Buildings constructed over sixty years ago in many different
climates have proven AAC to be one of the most durable
building materials available. Recommended where termites
are a concern.
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Low Construction Cost |
In addition to these outstanding product
features, independent studies has shown AAC to be a cost-effective
alternative to existing building materials. The homeowner
can get all the benefits of AAC without paying a high
premium for the extra sound, fire and thermal insulation
features.
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Design Flexibility |
AAC can be drilled, sawed, nailed, chiselled....
basically, one may work Autoclaved Aerated Concrete like
wood, using woodworking tools. Unlike standard concrete,
AAC yields readily without chipping or cracking. Creative
builders, architects, sculptors take note: AAC succeeds
whether you want to design elaborate details, cut exacting
angles, or render artistic carvings. With AAC, you can
be as eccentric or as traditional as you like.
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Breathable |
Another benefit of an AAC wall is the
approved stucco and acrylic finishes that are breathable
while still being water resistant. Interior and exterior
finishes have been formulated as one-way moisture barriers
allowing vapour to escape thus preventing condensation,
mildew and potential structural damage. In addition, cladding
such as brick veneer, stone or siding may be applied to
AAC walls.
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Sound Absorbent |
A commonly overlooked environmental problem
in residential construction is that of noise. The solid
wall construction of a building made of AAC provides excellent
sound abatement, greatly reducing outside environmental
noise, providing a quieter, more comfortable interior
for the occupants.
AAC’s porous structure and high surface mass, coupled
with its ability to dampen mechanical vibration energy,
make for a building material that provides an outstanding
defense against noise pollution.
Ecolite Products
ECOLITE MASONRY Wall Systems
and Panels
Ecolite purchases AAC masonry block in
a variety of sizes, shapes and different densities, then
prefabricates the wall. Blocks are used in both load bearing
and non-load bearing situations.
ECOLITE MASONRY Precast Wall
Panels
Ecolite wall panels are used as exterior
cladding, exterior load bearing walls and numerous interior
applications, both load bearing and non-load bearing.
They are reinforced with corrosion-protected steel reinforcement
wire.
ECOLITE MASONRY Precast Floor
Panels
Ecolite floor panels are steel-reinforced,
wired panels that are available in various sizes and strengths
to suit a range of spans and design loads. Their precision
fit and light weight make installation fast and economical.
ECOLITE MASONRY Precast Roof
Panels
Ecolite roof panels are very similar
to the floor panels with respect to geometry, physical
characteristics and erection procedures. They are generally
designed as flat decks with some type of water proof membrane
and can be supported with sloped roof trusses.
To see sizes and shapes of roof panels click here.
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