Användning av alternativa material i vägkonstruktioner
Sammanfattning: The report is based on the use of alternative materials in road construction. The alternative materials included are crushed concrete, crushed asphalt and air cooled blast furnace slag. Differences and similarities exist between the use of alternative materials in Sweden and Denmark. Denmark has no use of air cooled blast furnace slag, but they have a greater use of crushed concrete and crushed asphalt. In Sweden all three materials in the report are used in road construction. The results of the report are based on a literature study and a life cycle analysis. Crushed concrete is extracted from demolition objects as well as from leftover materials during manufacture. The concrete is crushed and filtered to be used as ballast in road constructions. Crushed concrete is a stiff material that gives a stiffer road construction compared to traditional materials. It also provides the same resistance to permanent deformations as traditional materials. Crushed asphalt is extracted from old layers of asphalt that are exhumed or milled and then crushed and sifted to be used as ballast in road structures. Crushed asphalt is also a material that helps to give road construction a lot of stiffness, but it is less resistant to permanent deformations than traditional materials. Air cooled blast furnace slag is a slag product from the iron industry and is obtained by air-cooling of the slag that occurs in the production of pig iron. Air cooled blast furnace slag provides a stiffer road construction and has the same resistance to permanent deformations as traditional materials. The life cycle analysis in the report is based on road structures where layers of traditional materials have been replaced by layers of alternative materials, which have then been compared to each other to see how the emissions vary when using alternative materials. The life cycle analysis shows that the use of alternative materials gives rise to less emissions when building roads compared with the use of virgin materials. The conclusion from the report is that the use of alternative materials should be promoted as it can reduce emissions in construction and reduce economic costs. This because some layers in the road construction can be reduced as the alternative materials are stiffer and the layers can be reduced without risking not to meet the requirements on the road.
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