Pozibreak - Salt Barrier
High strength cuspated core supports the bonded geotextile and prevents the void closing under the action of the soil pressure.
Pozibreak - Salt Barrier
Pozibreak Salt Barrier is designed specifically as a drainage void layer installed to protect imported clean soils from the rise of saline ground water through capillary action.
- Protecting vegetation from saline groundwater
- Salt Barrier
- Providing a capillary break over contaminated groundwater
- Frost Barrier
- Rapid installation
- Reduced material movements on site
- Eliminates the requirement for imported filter stone
- High impact and crush strength
- High flow capacity
- Ease and speed of installation without specialist equipment
- Provides a true capillary break against the rise of saline water
In deserts and arid regions, the groundwater is often saline and the water table can be relatively close to the surface. The capillary rise above the water table brings dissolved salts near to the surface of the ground. This results in severe problems for vegetation and the foundations of building structures.
Landscaping within modern developments in arid regions is particularly at risk. Most vegetation is intolerant of even slightly saline water (3-6 g/litre). Saline moisture must be prevented from reaching the root system of the vegetation. Similarly, it is important that irrigation water has minimal salt content to minimise the risk of salination of the soil (<0.5 g/litre no risk; 0.5-2g/litre moderate risk). For vegetation to survive, it is essential that there is a barrier between the saline ground and the clean ground and that this barrier also provides good drainage.
Building foundations of stone and reinforced concrete are designed for long term strength but this is compromised when saline moisture attacks the concrete. Chloride ions within saline moisture are drawn into stone and concrete where the resultant chemical reaction causes expansion, spalling and weakening of the foundations. It is important that there is a barrier between saline ground and clean ground in which foundations are constructed.
An effective barrier is to provide a capillary break layer between saline ground and clean ground. The capillary break layer creates a void across which capillary rise of saline moisture is prevented. It is essential that the capillary break layer is installed above the highest level of the water table so that the void is never totally saturated by ground water and that the capillary break has high in-plane flow capacity so as to remove sub-surface and irrigation water that enters through the clean ground above.
High performance geocomposites, such as Pozibreak Salt Barrier, are the preferred choice for the salt barrier capillary break layer. This is because the cuspated core maintains an open void with its high compressive strength and excellent support to the geotextile surfaces under the action of soil pressure as tested to ISO 12958 with SOFT PLATENS. Performance is further enhanced in Pozibreak Unperforated, where the lower side of the cuspated core provides a practically impermeable barrier to the rising saline moisture.
The capillary break layer is typically laid at a shallow gradient (eg. 3%) and the in-plane flow capacity will be significantly lower than at a hydraulic gradient (HG) of 1 (ie. vertical). The volume of irrigation water coming down through the soil above will be governed either by the irrigation rate or by the permeability of the soil. If the soil permeability is 1 x 10-6 m/s this equates to a water volume of 1 x 10-3 l/m2·s
In a 100m length of salt barrier this creates a flow of 0.1 l/m·s. A Pozibreak 7 with a flow capacity (MD+CMD) of 2.4 l/m·s at HG1 and 20kPa soil pressure has a flow capacity of 0.35 l/m·s at HG 0.03 and 20 kPa to ISO 12958 with soft platens.
The Pozibreak salt barrier should not reach full saturation so take 30% of its maximum capacity. That gives 0.11 l/m·s and the Pozibreak 7 is satisfactory. If the soil permeability is 1 x 10-5 m/s then there would be 10 times more water from the soil (if the irrigation rate allows) and therefore Pozibreak 7 would allow only a 10 metre maximum length of salt barrier; alternatively use Pozibreak 25 with a flow capacity of 2.1 l/m·s at HG 0.03 for the 100m length.
Typical Client Profile:
- Landscape Architects
- Landscaping Contractors
- Coastal / Marine Engineers
- Saltwater Canal and River Engineers
- Consulting Engineers
- Ministries of Public Affairs
The following similar products provide solutions for drainage and may be relevant:
Case Studies / Recent Projects:
Pozibreak has been installed on the following recent projects:
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