Sep 13 2004
Wood, one of the oldest materials known to man, is also one of the most fascinating. By the same token, however, this familiar material does have its limits in terms of its uses. For example, being a natural raw material, wood is not resistant to weathering. Also, the high tendency of the material to warp has meant that engineers have had to look for alternatives in some areas where wood is traditionally used.
"Eslon Neo Lumber FFU" is an extremely dimensionally stable composite material made from Baydur® 60 grade reinforced with long glass fibers produced by Sumika Bayer Urethane Co. Ltd., a subsidiary of Bayer MaterialScience AG. The Japanese company Sekisui Chemical has successfully sold this product for over 20 years as a construction material in the Asian market where the sophisticated composite material has proved successful in a wide variety of fields. Specifically, it is used for applications where it is not possible to use wood, either due to technical or economic reasons but where wood would have been the material of choice based on how easy it is to process. The most common applications of the composite material are pools for fish farming, silos, walkways, soil anchors (in this instance as a substitute for concrete) and above all railway sleepers. The tracks for the Japanese high-speed train Shinkansen for instance have been laid on polyurethane sleepers.
Now the versatile composite material has made its debut in Europe. As part of a renovation project, for the first time ever the tracks on the Zollamt bridge in Vienna have been laid on sleepers made from polyurethane.
"Eslon Neo Lumber FFU is particularly suited to use on bridges as it offers clear advantages over wood", says Michael Schwittlinsky from Sekisui Chemical Germany. "Temperature changes, UV radiation and in particular the permanent moisture in the air mean that wooden sleepers weather more quickly here than in other areas of application. The problem is that making structural improvements to railway tracks involves not only considerable inconvenience but also high costs." Consequently, in these and similar areas of application, materials which have a long life in these conditions soon pay for themselves.
Eslon Neo Lumber FFU (FFU stands for fiber reinforced foamed urethane) is produced at Sekisui in almost any required length using the pultrusion process. It looks like wood and combines all positive attributes of the natural product with those of a modern composite material. The Eslon Neo Lumber sleepers can be screwed together, nailed or sawed using conventional woodworking tools and also adhere together superbly, with even a stronger bond than that which wood produces. Other positive features are a low linear coefficient of thermal expansion and low thermal conductivity values. Thanks to the closed cell structure of the light polyurethane-glass fiber compound they absorb only a minimal amount of water. Due to the material's fiber reinforcement, its high compressive and tensile strength place it among the current top high-tech construction materials.
For more information on polyurethane, click here.