Pozidrain Capillary Break layer is designed specifically as a drainage void layer installed to protect the imported clean soils from the rise of contaminated ground through capillary action, and as a salt barrier where saline groundwater and surface water are to be separated.
High strength cuspated core supports the bonded geotextile and prevents the void closing under the action of the soil pressure.
Pozidrain Capillary Break
Applications
- Protecting vegetation from saline groundwater
- Salt Barrier
- Providing a capillary break over contaminated groundwater
- Frost Barrier
Benefits
- 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
The Pozidrain Capillary Break uses a cuspated core, since it is essential that the void is maintained, and that the upper and lower geotextile layers cannot touch each other under the action of the soil pressure. Similarly, unless the core is impermeable on one side, it is essential that the core does not become totally saturated and therefore the core must have a very high lateral in-plane flow capacity in multiple directions.
There are two forms of Capillary Break layer:
Single
The Pozidrain single-cuspated core option provides good long-term compressive strength, with a practically impermeable lower side and a very high multi-directional flow capacity, laminated to a non-woven geotextile.
The geotextile allows clean sub-surface water to freely enter the core, but prevents intrusion of soil. The core maintains the void by providing excellent support to the geotextile and transmits the clean water horizontally to collection pipes. Where required this enables the recycling of irrigation water.
The virtually impermeable lower side of the core provides a barrier to capillary water rise for added protection. This is a particularly useful feature when saline water cannot be allowed to mix with the clean water.
The impermeable nature of the core means that saturation of the void at local low spots can be permitted without affecting the integrity of the barrier.
The practically impermeable lower side of the core provides a barrier to the capillary water for added protection in addition to the void. This is a particularly useful feature when saline or contaminated water cannot be allowed to mix with the clean water.
The impermeable core means that saturation of the core void at local low spots can be permitted without risk of breaching the integrity of the barrier.
Double
The double-cuspated Pozidrain product is laminated to non-woven geotextiles on both sides and provides good long-term compressive strength whilst delivering high in-plane flow capacity in multiple directions.
The geotextiles allow water to freely enter the core, but prevent intrusion of the soils into the core. The core drainage void creates a path for excess water to flow horizontally and protects against soil intrusion by providing excellent support to the geotextile layers
The impermeable nature of the double cuspated core helps to manage and channel groundwater for re-use and provides a barrier against capillary salt water rise. This is more effective than alternative methods, whereby their permeability gives rise to contamination of the cover soil whenever the water table rises through the product, or more simply through evapotranspiration.
The in-plane flow capacity of the core must be designed to remove all of the expected sub-surface water entry from the overlying soil, without the core becoming saturated at the site designed specific gradient and outfall/collector spacing.
Both single and double cuspated versions use non-woven geotextiles, selected for compatibility with a wide range of soils but ABG will perform site specific designs when requested. The upper geotextile is hydrophilic with zero break through head, which means that water will pass without resistance. This is particularly important when the overlying soil layer is relatively thin.
Capillary Break is installed above the water table and can be installed quickly and easily without specialist equipment and with simple training for the installation team.
Typical Client Profile
- Landscape Architects
- Landscaping Contractors
- Coastal / Marine Engineers
- Saltwater Canal and River Engineers
- Consulting Engineers
- Ministries of Public Affairs