Infiltration areas
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As infiltration enabled traffic area surface mounting in is road construction called that surface water can seep into a larger scale at the place of occurrence. An application as an infiltration system that absorbs other surface water sources is less common. In the valid in Germany Data Sheet for Permeable traffic areas of FGSV the pavers with permeable paving systems, paving stones with Sickerfugen be porous asphalt layers and drain concrete layers described. The application with paving systems is the most widespread pavement that can be percolated. Greenable coverings are also used for unsealing. These pavements are listed in the guidelines for the planning, execution and maintenance of green pavements of the FLL . From a structural engineering point of view, water-bound surface layers are not infiltrable traffic areas.
The first applications of infiltrable traffic areas took place in the 1980s. In the 1990s, the first scientific studies were carried out and published on the basis of practical use. The basic rules of construction were described in Germany in 1998 in the FGSV's leaflet for water-permeable fastenings for traffic areas .
Objectives of the construction
The increasing surface sealing can be reduced by building traffic areas that can be infiltrated . Suitable old areas can also be unsealed and used again. In classic road construction, for example, according to the guidelines for the construction of road drainage , a runoff coefficient of 0.9 is applied , regardless of the choice of surface . This corresponds to a 90% runoff of the rainwater. These runoff quantities can be significantly reduced by means of surface pavements designed to be seepage. The lower and delayed flow rates of such pavements reduce the burden on the sewer system and sewage treatment plants . At the same time, due to the more humid ambient conditions, the microclimate is improved and at least a temporary cooling of the environment is promoted.
Basics
Ecological principles
According to the current opinion, pavements capable of seepage can be created in Germany without a permit, since they do not interfere with the natural water cycle according to Section 7 of the Water Management Act. Furthermore, the state regulations and local guidelines should be applied. In the case of traffic areas that can be infiltrated, the protection of soil and groundwater should always be in the foreground. Therefore, it must not be used if the distance to the groundwater is less than 2 m and substances hazardous to water are stored and transported in or on these areas. The use of de-icing salts should also be excluded. Infiltration paving may only be built outside of water protection zones.
Hydrological principles
A rain event of 120 l / (s * ha) is assumed as the basis for calculating the hydrological properties. On the basis of this measurement value, a five-year rain event (n = 0.2) of 270 l / (s * ha) is taken as a basis using the time coefficient method. Experience has shown that the movement of water is reduced by around 50% due to the air-filled pore space. It follows that the value for water permeability must be set twice as high as the infiltration rate. According to the German leaflet for infiltratable traffic areas , infiltratable layers must have a permeability coefficient k f > 5 * 10 −5 m / s. This value is based on a rainfall of 270 l / (s * ha) (k i = 2.7 * 10 −5 m / s). In the application, the drainage should be dimensioned according to RAS-Ew. Since the permeability of the surface layers decreases over the years, drainage coefficients of 0.3 to 0.5 should be applied to traffic areas that can be infiltrated. Paving systems tested on a scientific and expert basis may be included in the drainage calculation with lower runoff coefficients. Products with appropriate drainage joints can be viewed as permanently free of runoff (runoff coefficient ψ = 0.0) if they are installed properly and under the appropriate environmental conditions.
Road construction principles
According to the traditional principles of road construction, rainwater should be kept away from the superstructure . This principle is not used when using paving systems capable of seeping through. Therefore, permeable coverings can only be permanently installed in a system that is tailored to this construction method. The permeability must be given in all - i.e. also in the deeper - layers (subsoil), whereby substitute measures are possible if the subsoil is less permeable to water. Paving methods capable of seepage have a lower performance compared to conventional paving due to the void-rich bedding and joint material. Therefore, in Germany, for example, in the same load classes according to RStO compared to conventional construction, additional thicknesses have to be considered. The filter stability should be assessed according to the ZTV plaster. Due to the water permeability, the flow pressure can shift fine parts.
According to the German leaflet, the slope of the surface paving should be in the range of 1 to 5% in order to keep surface runoff low. According to scientific studies by the Technical University of Kaiserslautern, pavements with a gradient of more than 5% can also be laid.
construction
In the leaflet for infiltratable traffic areas , open-pored bound base courses are described and requirements for unbound base courses under pavement are specified. The drainage asphalt and drainage concrete base layers described may also be installed under conventional paving slabs and paving slabs. Paving slabs capable of seepage are usually laid on base layers without binding agents. According to the state of the art, the use of open-pored bound base layers would also be possible for water-permeable paving systems. According to the German leaflet, it is recommended to limit the deviations from the evenness on the base course to ± 1 cm over a 4 m measuring section.
Base courses without binders
In Germany, the base layers under pavements capable of seepage should be dimensioned according to the guidelines for the standardization of the superstructure of traffic areas (RStO 12). The load-bearing capacity and stability of the layers without binders is also selected depending on the traffic load according to RStO. Mixtures with little sand should be preferred, which run in the lower to middle grading curve range according to TL SoB. The fine grain fraction of grain size 0.063 mm should be max. 3 mass%. The permeability of the unbound base layers must be at least 5 * 10 −5 m / s and should be approximately determined by infiltration measurements after installation.
Water-permeable asphalt base courses
According to the leaflet for infiltratable traffic areas , water-permeable asphalt base layers PA 22 T WDA and PA 16 T WDA can be used under paved areas. The dimensioning is based on the load class according to the RStO. The use of geotextiles should be checked in order to achieve adequate filter stability.
Drainage concrete base layers
According to the German leaflet, drainage concrete base layers C 12/15 and C 16/20 can be used under paved areas. The dimensioning takes place depending on the traffic load according to the RStO. The use of higher quality drainage concrete cover layers as a base layer can be useful in higher load classes . In order to achieve sufficient filter stability for the pavement, geotextiles of the geotextile robustness class GRK 4 or GRK 5 with the highest possible water permeability according to the information sheet on drain concrete base layers should be used.
Infiltratable plasters
Permeable pavements can use structure-tight paving stones or haufwerkporigen be made concrete blocks. Concrete, clinker and natural stone paving stones are suitable as structurally dense paving stones for coverings that are capable of seeping through. Such cover layers can be laid with drainage joints or widened drainage joints. Seepage joints are joints filled with suitable material and with widths permitted in accordance with DIN 18318 (in Germany). In practice, widened seepage joints can have joint widths of up to 3 cm. To ensure appropriate process and operational reliability, the stones used should have suitable spacers. Additional spacing aids such as cross spacers or lawn cross spacers can only be used with significant compromises in terms of load capacity.
Pore concrete blocks (drainage concrete blocks) are manufactured in accordance with DIN 18507. Such concrete blocks with an open-pore character seep through the structure of the stone and additionally through the joint space. Pore-free concrete blocks are only frost-resistant and should therefore not be used in areas where de-icing salt exposure is to be expected. Due to their low compressive strength, concrete blocks with pores and pores should only be used in traffic areas with low loads.
Paving slabs capable of seepage are dimensioned differently from the RStO. Due to the low-sand joint and bedding materials, such cover layers can have a somewhat more flexible behavior and generally absorb lower horizontal stresses compared to conventional paving structures. According to the leaflet for traffic areas that can be infiltrated , a higher stone thickness than the RStO is recommended.
Dimensioning
| Load class | Paving stones with drainage joints | RStO 2012 1 |
|---|---|---|
| Bk 0.1 2 | 8 cm | - |
| Bk 0.3 | 10 centimeters | 8 cm |
| Bk 1.0 | 12 cm | 8 cm |
| Bk 1.8 | 14 cm | 10 centimeters |
Joint and bedding materials
Sufficiently water-permeable aggregates can be used as joint and bedding materials . In particular, the proportion of components of the 0.063 mm grain group that can be drained is limited to 1.0% by mass according to the information sheet for traffic areas that can percolate . Mixtures of grit sizes 1/3, 2/4 and 2/5 are preferably used. The joint and bedding materials should have increased material strength and a resistance to grain fragmentation of> SZ22 / LA25.
Green pavement and paving slabs
Green paving and paving are characterized by a medium to high proportion of green in the joints. Due to the sealing effect of the root system, these surface pavements were rather assumed to have a runoff delay with a runoff coefficient of 0.5. Investigations by the State Institute for Viticulture and Horticulture in Veitshöchheim have shown that green coverings can have a high seepage rate. Green paving and paving slabs can also be loaded with heavy goods vehicles according to the German FLL guidelines, depending on the stone height and slab thickness. In further literature there are clear application limits, especially for grass paving slabs with reduced concrete cross-sections.
literature
- Sönke Borgwardt: The professional application of infiltratable concrete paving systems . SLG, Bonn 1996.
- Sönke Borgwardt: Planning and execution of concrete pavements . Expert Verlag, Renningen-Malmsheim 1998.
- Sönke Borgwardt, Dietmar Ulonska: The professional application of infiltratable concrete paving systems . SLG, Bonn 2008.
- Alexander Eichler: Ecological paving systems in accordance with the RStO . grünForum.LA, September 2004.
- Jürgen Eppel, Jochen Böker: Soak away with plaster . New landscape, 2009.
- Marc Illgen: The seepage behavior of permeable paved settlement areas and its urban hydrological quantification . Technical University of Kaiserslautern, Kaiserslautern 2010.
- Horst Mentlein: Pavement Atlas . Rudolf Müller Verlag, Cologne 2007.
Standards and guidelines
Germany
- DIN 18318 traffic route construction work - paving slabs and slab coverings in unbound execution, edging
- DIN 18507 paving stones made of porous concrete - terms, requirements, tests, monitoring
- Additional technical contract conditions and guidelines for the production of paving slabs, paving slabs and edging (ZTV Pflaster-StB 06)
- Technical delivery conditions for construction products for the production of paving slabs, paving slabs and edging (TL Pflaster – StB 06)
- Guidelines for the standardization of the superstructure of traffic areas (RStO 12)
- Guideline for the planning, execution and maintenance of green pavements
- Leaflet for infiltration areas
- Leaflet on water-permeable pavements for traffic areas
- Leaflet for drainage concrete base layers
Austria
- 06/11/61 drainage behavior (November 1995)
Europe
- DIN EN 1338 Concrete paving stones - Requirements and test methods
- DIN EN 1341 natural stone paving slabs for outdoor areas - requirements and test methods
- DIN EN 1344 paving bricks - Requirements and test methods
Individual evidence
- ↑ Leaflet for infiltration areas .
- ↑ Guideline for the planning, execution and maintenance of green pavements .
- ↑ Sönke Borgwardt: The professional application of infiltratable concrete paving systems . SLG, Bonn 1996.
- ↑ Leaflet for water-permeable paving of traffic areas .
- ↑ Marc Illgen: The seepage behavior of permeable paved settlement areas and its urban hydrological quantification . Technical University of Kaiserslautern, Kaiserslautern 2010.
- ↑ Leaflet on drainage concrete base layers .
- ↑ Leaflet for infiltration areas .
- ↑ Leaflet on water-permeable pavements for traffic areas .
- ↑ Jürgen Eppel, Jochen Böker: Sick away with plaster . New landscape, 2009.
- ↑ Alexander Eichler: Ecological plaster systems in accordance with the RStO . grünForum.LA, September 2004.