Ceiling (road construction)
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(with dam position)
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The upper part of the road surface is referred to as the ceiling (also surface layer or road surface, also road surface ) . The previously used terms top layer , road surface or pavement surface are no longer used in technical terms. One or more base layers are located below the top layer . A combination of both parts is wearing course called. Particularly high quality requirements are placed on top layers. Their thickness and composition depend on the traffic load and the associated design-relevant stress (equivalent 10-t axle transitions).
Asphalt surface courses
Asphalt surface courses consist of a graded aggregate mixture and bitumen as a binding agent. They are the most commonly used top layers. These include surface layers made of mastic asphalt , stone mastic asphalt , asphalt concrete . Asphalt mastic and open-pored asphalt, also known as drain asphalt, are installed less frequently . Together with the asphalt binder course , the asphalt surface course forms the asphalt surface. Asphalt surface courses are carried out with a thickness of 3 to 4 cm. Depending on the traffic, they have a shelf life of 12 to 18 years.
Mastic asphalt has a high proportion of filler (very fine material) and binding agent. It is installed at max. 230 ° C with mastic asphalt cookers . During paving, the mastic asphalt can be poured, poured and spread, and unlike other asphalts, mastic asphalt is not compacted. Nevertheless, once it has hardened, it is almost free of voids.
Mastic asphalt is installed,
- when the road is subject to heavy traffic, such as on motorways or main roads
- when it is particularly important that no water penetrates the road structure, such as on bridges or
- if the installed surface layer cannot be compacted, as in machine halls, which continue to produce during the installation and would be severely disturbed by the compacting (vibrating rollers, shaking, tamping).
Disadvantages are the very high installation temperature required and the high costs.
Asphalt concrete contains a uniform grain gradation and an average grit content of around 50 mass % . It is manufactured in asphalt mixing plants at a temperature of 160 ° C. Asphalt concrete is paved and pre-compacted with the black pavement paver , which pre-compacts the pavement up to 90%, and subsequent compaction is carried out with vibratory rollers.
Stone mastic asphalt
The high stability of the stone mastic asphalt is achieved through its high share of chippings. This is associated with a small proportion of sand, which can lead to the binder running off and the grain material separating. To prevent this, the binder content is increased and stabilizing additives are added to the stone mastic asphalt, such as cellulose fibers, polymer granulate or special fillers. Stone mastic asphalt must be intensively compacted in order to achieve the required degree of compaction; With the usual paving thickness of 3 to 4 cm, compaction is carried out by means of vibration rollers and static rollers.
Asphalt binder course
Asphalt binder, also called asphalt binder course or binder course, is installed on roads with high traffic loads as a connecting layer between the surface and the bituminous base course. These correspond to the load classes BK100, BK32, BK10 and BK3,2. It consists of mineral mixes with a graded grain size. Road construction bitumen or polymer-modified bitumen is used as a binding agent. This creates a stable layer, the density and size of which is only slightly changed by the traffic.
Asphalt base course
The asphalt base layer is the lowest layer of the bituminous paving of the superstructure. The asphalt base layer rests on an unbound mineral layer (frost protection layer). Their main task, in addition to securing the load-bearing capacity of the layers of the asphalt pavement above, is the distribution and safe discharge of traffic loads into the ground. The total thickness of this layer depends on the building classes in accordance with the guidelines for the standardization of the superstructure of traffic areas (RStO).
Concrete ceilings consist of a graded mineral mixture and cement as a binding agent. Concrete ceilings are preferred for roads with high traffic, such as highways. They are very permanent and can last for 30 to 40 years.
Concrete cover layers are implemented with a thickness of 18 to 30 cm. They consist of slabs 5 to 6 m long without reinforcement . It is important to provide the concrete with joints . These prevent wild cracks, as can occur when setting, and compensate for changes in length due to temperature fluctuations. When it comes to joints, a distinction is made between space joints , dummy joints and press joints . Then the joints are filled . This prevents solids or liquids from penetrating, which would hinder the free movement of the plates relative to one another.
The individual concrete slabs are connected to one another with dowels (transverse joints) and anchors (longitudinal joints). Dowels ensure the transfer of loads and secure the height of the concrete slab in the longitudinal direction. Anchors prevent the panels from moving apart. Concrete ceilings are used at bus stations and bus stops with heavy traffic, where the flowing of asphalt would quickly create ruts.
Pavers are mainly made from natural stone , concrete stone and clinker paving . Two fundamentally different construction methods are used in production. These are the unbound and the bound pavement construction. Pavers must not be used in areas with high traffic loads ( load class 100, 32 or 10 according to RSTO 2012). Compared to asphalt and concrete ceilings, paved surfaces offer the advantage of extensive design options.
Top layer without binder
A top layer without a binding agent (DoB) is a layer that is only made from a graded mineral mixture. DoB are preferred in agricultural and rural road construction. The term “ water-bound ceiling ” or “Grand fortification” and, more commonly, “gravel road” has emerged in linguistic usage .
Top layer with epoxy resin bond
On the basis of a top layer without a binder (DoB), an additional superstructure made of minerals that are bound with epoxy resin can be built. This superstructure is much stronger (than DoB), but at the same time water and air permeable.
The “Luwadur” system, which has been in use since 2011, is typical.
Top layer with salt binding
An additional superstructure made of salt can be built on the basis of a surface layer without binding agents (DoB). This superstructure is significantly stronger (than DoB), and is also permeable to water and air. This surface is used in the coastal regions of Namibia .
Norms and standards
Proof of the importance of improving road surfaces is the "Commission for the selection of streets to be covered with granite tracks" that existed in Berlin in the 1880s.
- ZTV Asphalt-Stb 07: Additional technical contract conditions and guidelines for the construction of asphalt road surfaces
- ZTV Beton-StB 07: Additional technical contract conditions and guidelines for the construction of ... concrete road pavements
- ZTV Pflaster-StB 06: Additional technical contract conditions and guidelines for the construction of paving slabs and paving slabs
- DIN 18315: traffic route construction work, superstructure layers without binding agents
- DIN 18316: traffic route construction work, superstructure layers with hydraulic binders
- DIN 18317: traffic route construction work, pavement layers made of asphalt
- DIN 18318: Traffic route construction work, paving slabs, paving, edging
- RSTO 2012: Guidelines for the standardization of the superstructure of traffic areas
- RVS 03.08.63 superstructure measurement
- RVS 08.16 Bituminous base and top layers
- RVS 08.17 concrete ceilings, cement-stabilized base layers
- RVS 08.18.01 Paving stone and paving slab ceilings, edging
- SN 640 324 Dimensioning of road superstructure
- SN 640 461b concrete ceilings, conception, implementation
- ITF: Long-life Surfacings for Roads: Field Test Results . OECD Publishing, Paris 2017. doi: 10.1787 / 9789282108116-en .
- Research for Roads and Transport: Definition of the part road construction technology . Edition 2003, FGSV-Verlag, Cologne, FGSV 924
- Homepage of the Luwadur® brand
- Homepage of the sales partner
- Example for use by a construction company
- Klaus Dierks : Chapter 4.3 Phase Three from 1945 to 1952. In: Naminian Roads in History. Institute for Economic and Social Geography of the Johann Wolfgang Goethe University Frankfurt / Main, January 10, 2001, accessed on November 13, 2019 (English).
- Municipal authorities . In: Berliner Adreßbuch , 1880, IV. Theil, p. 58.