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Sustainability
| Amid a growing
awareness in construction practices to preserve resources,
conserve energy, and protect the environment, the construction
industry is embracing the concept of sustainable development––the
ability to build the facilities and structures we need
today without depleting resources for the future. Sustainability
seeks to balance the economic, social and environmental
impacts, recognizing that population growth will continue.
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©Recycled Aggregate
Image compliments of the PCA. |
Up to 40% of all materials used in human
activity is directed into the built environment. This has
a direct and visible impact on the world’s resources,
energy consumption and carbon dioxide emissions. However,
concrete has an excellent ecological profile compared to other
construction materials such as metal, glass and polymers.
Although cement is both resource and energy intensive when
produced, compared to other products, concrete production
consumes the least amount of materials and energy, produces
the least amount of harmful by-products, and causes the least
amount of damage to the environment.
Concrete is a responsible choice for sustainable
development, in part due to its durability. Durability is
a significant sustainable attribute of concrete because it
will not rust, rot, or burn. Moreover, concrete structures
require less energy and resources overtime to repair or replace.
Structures built with concrete have optimal energy performance.
Additionally, concrete is easy to use, incurs little waste
and can be readily recycled.
The Case For Concrete
The focus on energy efficiency,
durability, and safety is both a challenge and an opportunity
for the concrete industry. Concrete has an impressive CV for
the job – its credentials include:
- It’s comfortable – with high-performance
thermal mass, insulation capacity and passive solar design
- It’s safe – fire resistant and stable
- It’s healthy – with a great capacity for
reducing noise, dust and chemical emissions. In some cases,
it can absorb chemicals from other materials and release
them from exposed surfaces
- It’s economical – promising long life with
low maintenance
- It’s unique – with properties that often
mean it is the only viable choice for the purpose
- It’s energy friendly – the energy requirements
for manufacture are low compared to most other building
materials
- It's durable - concrete has a life expectancy of 100
years when maintained – twice that of any other
material
Specifiers are
choosing concrete for its durability, recycled ingredients,
and energy efficiency not found in other building materials
like steel or wood. When compared with other building
materials, concrete is a responsible choice for sustainable
development. Sustainable development challenges the
design and construction industry to create buildings
that acknowledge the life cycle of a building. Recognizing
that operating a building over time is far more energy
intensive than developing it, demand for durability
and energy performance is growing. |
"Sustainability
is not achieved simply with the use of appropriate materials.
It is a marriage between design and construction philosophies
and practices. If sustainability is not understood and
specifically designed for, the benefits won’t
be achieved, no matter how suitable the materials may
be." |
Sustainable Manufacturing
Process
Concrete is easy to use and can be readily recycled. Delivered
and prepared for each specific project, concrete typically
produces very little waste. When a concrete structure has
served its purpose, it can be recycled as aggregate in new
concrete paving, backfill, or as road base. Even the reinforcing
steel in concrete (which often is made from recycled materials)
can be recycled and reused.
Current Recycling Efforts
in the Manufacture of Concrete:
- Fillers - the use of fly ash and slag as fillers for
blended cements is assisting in the disposal of by-products
from the energy generation business while decreasing the
energy intensity of cement production.
- Hazardous substances - many common wastes - such as
spent solvents, printing inks, paint residues and cleaning
fluids - are designated as hazardous because of their
high fuel value. In other words, they are flammable. Those
and other high-energy wastes such as motor oil and scrap
tyres cannot be disposed of safely on landfills. But they
can be safely burned to destruction as fuel in a cement
kiln while reducing our reliance on dwindling reserves
of fossil fuels. Already, waste motor oil is collected
and burnt in a cement kiln in New Zealand.
- Recycled Demolition Waste - Concrete is extensively
recycled, waste concrete from demolition sites can be
reused as aggregate for 'new' concrete, or in new roads.
Embodied Energy
Coefficients
| Cement |
MJ/kg |
MJ/m3 |
| Average |
9.0 |
17500 |
| Dry process |
7.7 |
15020 |
| Wet process |
10.4 |
20280 |
| Grout |
1.9 |
4560 |
| Mortar |
2.1 |
3360 |
| Fibre Cement Board |
10.9 |
15550 |
| Soil-cement |
0.7 |
1420 |
| Concrete |
MJ/kg |
MJ/m3 |
| Block-fill |
1.4 |
3150 |
| Block-fill, pump mix |
1.5 |
3430 |
| Grout |
1.7 |
2380 |
| 17.5 MPa pump mix |
1.2 |
2830 |
| Cement |
MJ/kg |
MJ/m3 |
| Kiln dried, average dressed |
5.09 |
2200 |
| Kiln dried, gas fired, dressed |
8.2 |
3550 |
| Kiln dried, waste fired, dressed |
3.1 |
1340 |
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Source: concrete June 1999.
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