For decades, RAVATHERM XPS extruded polystyrene foam thermal insulation has been successfully applied for the various purpose thermal insulation of roads, rail-way tracks, airport runways, and skating rinks, and for other structures under the ground level that is exposed to the danger of frost, primarily in the Scandinavian countries and in Russia.
In such cases the physical properties of the closed-cell polystyrene foam resulting from its unique material structure are especially important.
• excellent mechanical strength and high durability
• high, long-lasting thermal insulation performance
• lightweight and easy to handle
• easy to cut with simple tools
• not sensitive to moisture
• frost resistant
The globally increasing trends of built-in areas has frequently "expels" the construction sites of linear facilities to areas not quite suitable for building foundations. In case of frost susceptible soils extensive soil replacement or amelioration is very expensive (owing to the need to transport huge volumes of good quality soil to big distances). This is the reason behind the successful expansion of the use of the high loadability and low density closed-cell XPS which feature high load-bearing capacity and, at the same time, prevent problems arising from the frost sensitivity of the subsoil beneath the structures.
In grim application conditions, RAVATHERM XPS thermal insulation’ high strength, viscoelastic behavior, and resistance against moisture and frost are exploited in a complex way.
The railway lines must be provided with thermal insulation, in order to prevent displacement of the tracks. Designing of anti-frost protection presumes knowledge of the area's zonal and climatic features and the average number of frosty days. The RAVATHERM XPS thermal insulation products have been used since 1975 for anti-freeze insulation. Where the lower strata of the soil is exposed to effects of permafrost, the thermal insulation layer must be laid on the gravel bed. Up to 100 mm thickness, the RAVATHERM XPS plates may be placed in a single layer, close to each other, with staggered edge finishing, in order to avoid development of frost bridges.
In certain soil types frost can cause raising - the frost induces the movement and expansion of the soil - that can damage roads, railways, pipeline systems, and building foundations.
The thermal insulation must be laid on the track base by placing at least 300 mm thick gravel bed between the plates and the bottom side of the sleepers. When existing railway tracks are insulated, the thermal insulation plates must be loaded before insertion.
An efficient solution for the protection of these structures is thermal insulation using RAVATHERM XPS, which decreases the danger of frost damage and the associated repair and maintenance costs. This method of the prevention is often simpler and more cost-efficient than the construction of deep foundations resting on gravel beds.