Frost protection layer

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A frost protection layer ( FSS for short ) is part of the superstructure of road and path reinforcements and forms the lowest unbound base layer there . It is their job to prevent or minimize frost damage to the road structure . Insensitivity to frost is ensured by appropriately graded aggregates (low proportion of fine grains ) and adequate water permeability.

The most important property is the ability to have a “capillary breaking” effect. This prevents water from rising in the road.

Natural minerals (such as sand or gravel ) and artificial minerals ( blast furnace slag ) as well as recycled building materials (such as broken concrete) are suitable as aggregates for the frost protection layer . The installation thickness of the frost protection layer can be determined depending on the largest grain size, the expected traffic load and the frost sensitivity of the substructure or subsoil. The strength of the FSS is based on the corresponding guidelines for dimensioning the road surface in connection with the location of the road within a specific frost zone . The FSS may still contain cohesive components (i.e. grain diameter <0.063 mm) in the delivered condition of a maximum of 5% and in the installed condition a maximum of 7%. To the side, the FSS should be drained using a transverse slope on the subgrade .

Norms and standards

Germany
  • Guidelines for the standardization of the superstructure of traffic areas (RStO)
  • Additional technical contractual conditions and guidelines for layers without binders (ZTV SoB-StB) (since February 4, 2005, before that additional technical contractual conditions and guidelines for base layers in road construction (ZTV T-StB))
  • Technical delivery conditions for building material mixtures and soils for the production of layers without binding agents in road construction (TL SoB-StB) (Edition 2004 / Edition 2007)
Austria
  • RVS 03.08.63 superstructure design
  • RVS 08.15.01 Unbound base courses
Switzerland
  • SN 507708 - General conditions for road construction
  • SN 640741 - traffic areas with unbound superstructure - basic standard