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Sustainability Benefits of Concrete

sustainablecement.jpgIt is easy to overlook the use of concrete in society. Concrete plays a vital part in our daily lives and in a functioning society. Its benefits to society are immense, being used to build our schools, hospitals, apartment blocks, bridges, tunnels, dams, sewerage systems, pavements, runways, roads and more.

Few people realize that concrete is in fact the most used man-made material in the world, with nearly three tons used annually for each man, woman and child. Twice as much concrete is used around the world than the total of all other building materials, including wood, steel, plastic and aluminium. None of these other materials can replace concrete in terms of effectiveness, price and performance for most purposes.

Even fewer people are aware of the many environmental benefits that using concrete brings.

It is vitally important to develop products and systems that can be used to construct more durable, energy-efficient eco-buildings, and concrete can be used to do just this. Concrete, with its strength, durability and excellent thermal mass, should be a key component in eco-buildings of today and the future. In May 2008, The Guardian in the United Kingdom featured the first zero-carbon house developed by a volume housebuilder, in which concrete plays a critical role in maintaining internal temperatures.

The CSI has established a new working group to explore the qualities of concrete that will contribute to a more sustainable society.

The environmental benefits of concrete, among others, are:

 

Characteristics of Concrete

1

Strength and Durability
  • Used in the majority of buildings, bridges, tunnels and dams for its strength
  • Gains strength over time
  • Not weakened by moisture, mould or pests
  • Concrete structures can withstand natural disasters such as earthquakes and hurricanes
  • Roman buildings over 1,500 years old such as the Coliseum are living examples of the strength and durability of concrete

2

Versatility
  • Concrete is used in buildings, bridges, dams, tunnels, sewerage systems pavements, runways and even roads

3

Low maintenance
  • Concrete, being inert, compact and non-porous, does not attract mould or lose its key properties over time

4

Affordability
  • Compared to other comparable building materials e.g. steel, concrete is less costly to produce and remains extremely affordable

5

Fire-resistance
  • Being naturally fire-resistant concrete forms a highly effective barrier to fire spread

6

Relatively low emissions of CO2
  • CO2 emissions from concrete and cement production are relatively small compared to other building materials.
  • 80% of a buildings CO2 emissions are generated not by the production of the materials used in its construction, but in the electric utilities of the building over its life-cycle (e.g. lighting, heating, air-conditioning)

7

Energy efficiency in production
  • Producing concrete uses less energy than producing other comparable building materials.
  • A study quoted by the NRMCA concluded that the energy required to produce one ton of concrete was 1.4 GJ/t compared to 30 GJ/t for steel and 2GJ/t for wood
graph2
Energy of Production for Common Materials
Source: National Ready-Mixed Concrete Association (NRMCA)

8

Excellent thermal mass
  • Concrete walls and floors slow the passage of heat moving through, reducing temperature swings
  • This reduces energy needs from heating or air-conditioning, offering year-round energy savings over the life-time of the building
  • One study quoted by the NRMCA found that concrete walls reduce energy requirements for a typical home by more than 17%

9

Locally produced and used
  • The relative expense of land transport usually limits cement and concrete sales to within 300km of a plant site.
  • Very little cement and concrete is traded and transported internationally
  • This saves significantly on transport emissions of CO2 that would otherwise occur

10

Albedo effect
  • The high "albedo" (reflective qualities) of concrete used in pavements and building walls means more light is reflected and less heat is absorbed, resulting in cooler temperatures
  • This reduces the "urban heat island" effect prevalent in cities today, and hence reduces energy use for e.g. air-conditioning

 

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