For most of you recycling is something you will do at home every now and then, but little do you know that in your future jobs you will have the possibility to use recycled materials or re-use materials.
As you know concrete is one of the most widely used materials in the civil engineering industry. In the use of concrete there are vast possibilities for recycled or re-useable materials such as in the choice of aggregates; even crushed concrete from the demolition of old buildings can be used! A lot of other industrial by-products are also now being used and have been found to be particularly effective. The most common of these industrial by-products is Pulverised Fuel Ash (PFA), fine minute glass spheres produced when coal is burnt in power stations. The spheres are hollow and therefore very light, so can be used to make lighter concrete. Other power station by-products can be used, like silica fumes and ground granulated blast furnace slag. In interesting fact is that the state of Pennsylvania will now exclusively use concrete made from recycled material as it expects that these bridges will now have a 100 year working life, demonstrating the viability of these technologies.
One company who is pioneering the use of recycled materials in civil engineering is Re-Tread Products. They have developed a technique to recycle old tires and to turn them into a building material. By cutting off the side walls of tires, a strip is made from the tread material which is then tightly wound together to make a “pole” that can be used in retaining walls or flood protection.
Excavated material can become a major cost in a civil engineering project, but when possible an engineer should try and find a use for it. If suitable (when dealing with sand or alkali clay) the material could be used as an aggregate, but if the excavated material is structurally weak and as such unsuitable as an aggregate, there can be other use for it, such as using sand as a compacter to strengthen the ground (as used for Heathrow Terminal 5).
As can be seen here, when an engineer applies a bit of thought to his or her project and tries to include recycling materials or re-use waste, there are solutions to be found.
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