Sustainability

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.

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

Source: concrete June 1999.