For the repair or the new construction of a fresh water dyke, the 7 mm thick Bentofix® geosynthetic clay liner is an economical alternative when compared to the typical 60 cm thick compacted clay liner. When installed on the upstream surface, the high-swelling powdered sodium bentonite offers an excellent low permeability seal. Bentofix® is manufactured with direction independent needle punching, with more than two million fibres per square metre. Slope angles of 2.5 h : 1 v or greater are possible due to the surface structure of the needle-punched cover and carrier nonwovens as well as the large internal and external shear strength. In poor soil conditions or on steeper slopes, Secugrid® geogrids can be used to further ensure slope stability.
Due to their thin profile, Bentofix® clay liners consume less volume than compacted clay, and can require significantly less soil removal – especially in the case of dyke repair. The Bentofix® BFG 5000 also features a cover nonwoven geotextile that has been uniformly impregnated with a second layer of sodium bentonite powder over its entire surface area. The additional bentonite in the cover nonwoven geotextile can help the installation proceed more efficiently versus installations where the overlaps must be sealed with additional bentonite.
The cover and carrier geotextiles of Bentofix® geosynthetic clay liners protect the bentonite core while providing sufficient robustness for on-site handling. When high normal loads are anticipated, Bentofix® manufactured with nonwoven geotextiles exhibiting a mass per unit area of 300 g/m² should be used.
Alternatively, 1.5 mm thick Carbofol® HDPE geomembranes can be installed. Not only is placement simple, Carbofol® HDPE geomembranes are easy to weld due to the favorable Melt Flow Index of the resin.
Surface texturing is available to effectively transfer shear forces on slope locations. Regardless, project-specific direct shear tests should be performed to verify the required shear strength parameters of the confining soils and to calculate the stability.
Depending on the requirements, needle-punched nonwoven geotextiles such as Terrafix® or Secutex® may be installed above and below the Carbofol® geomembranes for added protection. For slightly gravelly-sand (gravel portion ≤ 30 %) protection nonwovens with a mass per unit area of 400 g/m² should be used to protect the Carbofol® geomembrane. Coarser grained soils may require protection nonwovens, exhibiting a mass per unit area of 1,200 g/m².