Green Concrete - Seminar Reports|PPT|PDF|DOC|Presentation

One of the major challenges of our present society is the protection of environment. Some of the important elements in this respect are the reduction of the consumption of energy and natural raw materials and consumption of waste materials. These topics are getting considerable attention under sustainable development nowadays.

Today engineers and architects have choices of the material and products they use to design projects – when it comes to a building frame the choice is typically between concrete, steel and wood; for paving applications the choice is generally between concrete and asphalt. For its suitability and adaptability with respect to the changing environment, the concrete must be such that it can conserve resources, protect the environment, economize and lead to proper utilization of energy. To achieve this, major emphasis must be laid on the use of wastes and byproducts in cement and concrete used for new constructions.

 Material choice depends on several factors including first cost, life cycle cost and performance for a specific application. Due to growing interest in sustainable development engineers and architects are motivated more than ever before to choose materials that are more sustainable. On what “measurement” basis can engineers and architects compare materials and choose one that is more sustainable or specify a material in such a way as to minimize environmental impact?

Life Cycle Assessment (LCA) seems to offer a solution. LCA considers materials over the course of their entire life cycle including material extraction, manufacturing, construction, operations, and finally reuse/recycling. LCA takes into account a full range of environmental impact indicators—including embodied energy, air and water pollution (including greenhouse gases), potable water consumption, solid waste and recycled content. just to name a few. Building rating systems such as LEED and Green Globes, are in various stages of incorporating LCA so that they can help engineers and architects select materials based on their environmental performance or specify materials in such a way as to minimize environmental impact.

Recent focus on climate change and the impact of greenhouse gas emissions on our environment has caused many to focus on CO2 emissions as the most critical environmental impact indicator. The problem with this approach is that it forces engineers, architects and product manufacturers to focus their efforts on reducing greenhouse gas emissions without regard to other sustainable practices. Even a small reduction of the environmental impact per tonne of concrete will result in large environmental benefits because of the vast amount of concrete produced today.

Concrete is also interesting in relation to other environmental problems than those related to CO2 emission. It may be possible to use residual products from other industries in the concrete production while still maintaining a high concrete quality. During the last few decades, society has become aware of the problems associated with landfilling of residual products, and limits, restrictions and taxes have been imposed. As several residual products have properties suited for concrete production, there is a large potential to increase material recycling by investigating the possible use of these for concrete production.

When assessing the environmental compatibility of concrete it is essential to consider all life cycle phases. This means that it is no longer sufficient to address environmental issues associated with the production of the individual building materials. The environmental impacts associated with the use and disposal of a structure has to be considered. The energy consumption and CO2 emission associated with the use of a structure are generally in the same magnitude or larger than the energy consumption and CO2 emission associated with production of the individual construction materials. Use, maintenance and durability are therefore important aspects, which have to be considered. A result of this is new qualifications are needed for the actors in the concrete construction sector. It is not enough for the individual producers to know the environmental performance of their own materials. Knowledge of the total environmental performance from cradle to grave is needed. Furthermore, a united business effort involving the relevant actors is needed in order to achieve real environmental improvements.

With this background it is important to reduce the environmental impact of the materials themselves not least because environmental improvement is a competitive parameter. Building materials with reduced environmental impact are often less expensive to produce. Furthermore, environmental performance is increasingly taken into account in tenders. The material with the best environmental parameters is most likely to be used.

According to the World Business Council for Sustainable Development, concrete is the most widely used substance on Earth apart from water. Approximately 2.35 billion tons of concrete are produced each year. That works out to a cubic meter, or about a 35- by 35- by 35-foot cube of concrete for each person on Earth every.