Waterborne ceiling , officially top layer without binder (symbol DoB), also Grand mounting and in Switzerland Chaussierung called, is in the streets - and road construction , the term for a special type of covering. This road surface consists of a graded mineral mixture of broken natural stone material - chippings and gravel , also called grand in the region - and is preferably used for agricultural purposes and in rural areas.
Paths with a water-bound cover are also called unpaved paths or gravel roads ; if the unpaved lane runs parallel to a paved surface, it is called a summer path . Road surfaces without a water-resistant binding agent for consolidation are only suitable for roads with low traffic loads and low driving speeds.
Manufacturing and function
The top surface is about two to four centimeters thick and rests on a six centimeter thick base layer that dynamically transfers pressure and thrust. Underneath are a layer of frost protection and the stable substructure . The material used is not held together by hydraulic or bituminous binders . Instead, the superstructure is applied to the moist base course, then compacted (rolled) - and then not loaded for a few weeks. Only the washing in of the top layers ensures the bond and thus a compact structure.
A characteristic of a path with a properly executed water-bound surface is that even narrow tires with high punctual pressure load do not leave any marks and the driving resistance at low speed is comparable to that on average asphalt surfaces .
If properly installed and properly maintained, water-bound ceilings lead to sufficient precipitation infiltration and therefore have a lower runoff coefficient than asphalt surfaces. In many nature parks they are the preferred form of paving machine-accessible paths, as they can convey a more natural impression. If light stone material is used, such surfaces also heat up significantly less than dark asphalt surfaces. In addition, the slightly softer surface is considered to be gentler on the joints for pedestrians or joggers and also for horses, whose hooves are also less stressed. The production costs are around two thirds of comparable asphalt surfaces. In addition to being used as a road surface for forest and agricultural roads, water-bound ceilings are also used in parks and parking spaces .
Water-bound ceilings are prone to erosion on inclines, as the top layer of the material can be removed during heavy rainfall. This makes the path bumpy, creating gullies and potholes . Especially in arid climates form washboard from. Maintenance of the paths is therefore required more often, especially after snow has been cleared.
Vehicle traffic at more than approx. 20 km / h on water-bound roads leads to the development of dust when it is dry and, due to being blown away, to wear of the upper surface layer. The high weights of modern agricultural vehicles are also problematic, as they considerably promote road damage such as potholes.
In some federal states, quality standards for cycle paths regulate the use of water-bound ceilings. In Saxony , for example, a decree regulates that they may not be used on inclines or in flood-flood areas and only in ecologically particularly sensitive areas.
Alternatives and rules
As alternatives to the water-bound ceiling, e.g. B. grass pavers , paving or asphalt in question.
The guideline for the standardization of the superstructure of traffic areas provides an approach to binding regulation .
- ↑ technikseiten.hsr.ch
- ↑ Horst Haffner: Places, Places, Rooms . Callwey, 2005, ISBN 3-7667-1650-6 , p. 28.
- ^ University of Natural Resources and Life Sciences, Vienna, 2010.
- ^ Decree of the Saxon State Ministry for Economics and Labor of March 11, 2005 on the quality standard of the Sachsennetz Rad, file number 52-3942.31 / RVK