North America

Bentofix® Thermal Lock® Geosynthetic Clay Liners (GCLs)

Q: What are Geosynthetic Clay Liners?

A:  Geosynthetic Clay Liners are factory manufactured, hydraulic barriers typically consisting of bentonite clay or other very low permeability materials, supported by geotextiles and/or geomembranes which are held together by needling, stitching or chemical adhesives.

Q: How is Bentofix® manufactured?

A:  Bentofix® consists of two types of geotextiles which has bentonite clay sandwiched in the middle of the two textiles. The Bentofix® Geosynthetic Clay Liner (GCL) is needled punched together. This is a process of inter locking the fibers from the cap textile through the bentonite to the carrier textile. This process is accomplished by the use of a machine which is equipped with many thousands of barbed needles. These barbed needles pick-up the fiber from the surface textile and drive them through the layers. This interlocks the textiles together with the bentonite clay sandwiched in between.

Q: What is Thermal Lock®?

A:  The Thermal Lock® procedure is a proprietary radiant heat treating process used in the manufacture of Bentofix® to fuse the needle punched fibers onto the surface of the carrier geotextile. A number of unique properties result from this procedure which include increased fiber bonding strength, and increased internal shear resistance.

Q: Are the geotextiles used in Bentofix® normal geotextiles found in other applications?

A:  The textiles used to manufacture Bentofix® GCLs are only used for Bentofix® and are not available for other applications. These textiles have been formulated to give Bentofix® the necessary final properties demanded by each application.

The cap nonwoven is constructed with a proprietary blend polypropylene of high tenacity virgin staple fibers. This blend of fibers is extremely important as the cap component of any needle punched GCL must provide containment of the sodium bentonite while also acting as the source of the reinforcing fibers.

The carrier slit film woven geotextile has been manufactured specifically for Bentofix® GCLs to achieve the manufacturing and final specifications for the application.

The carrier nonwoven geotextile includes a scrim-reinforcement to provide greater dimensional stability and higher strength.

Q: What is the difference between a reinforced GCL and an unreinforced GCL?

A:  A reinforced GCL such as a needle punched Bentofix® GCL has the textiles interlocked together to hold and bind the clay. An unreinforced GCL has the clay either glued or pressed to textiles or plastic membranes.

Advantages of reinforced Bentofix® GCL over the unreinforced GCL:
1. Provide greater protection against bentonite displacement especially when the cover soil will not be immediately placed
2. Provide significantly greater resistance to the potentially detrimental effects of differential settlement
3. Maintain GCL integrity when subjected to premature hydration
4. High internal shear strength making it’s use on slopes desirable

Q: Will Bentofix® Thermal Lock® GCL shrink in the field?

A:  High moisture content, adhered fabric GCLs are susceptible to contraction (or shrinkage) soon after field deployment while low moisture needle punched Bentofix® GCLs are not.

Q: If Bentofix® become prematurely hydrated do they have to replaced?

A:  Typically when the Bentofix® GCL becomes prematurely hydrated it does not have to be replaced. This of course is taken on a case by case basis. However, due to the needle punching, reinforcing the sodium bentonite between the two textiles the swelling of the bentonite is restricted in a confined area.

Q: Does seam enhancement with bentonite have to be used in deploying Bentofix®?

A:  Bentonite between the seams should be used in applications where Bentofix® is the primary liner material.

Q: What is the typical moisture content of the bentonite clays in Bentofix®?

A:  Bentofix® has the lowest amount of moisture in the bentonite clay than any other North American GCL. Our specification states a 12% moisture content vs. others of 25% to 40%.

Q: What is the panel size of a typical Bentofix® GCL?

A:  Bentofix® is typically sold in roll form which is 4.7 m (15.5 ft) wide and a roll length of 45 m (150 ft). This produces a total of 211.5 m² (2,325 ft²) per roll. As we are shipping less moisture than other GCL manufacturers we can ship 16 to 17 rolls per truck load which is a total of up to 3,596 m² (39,525 ft²) per truck load. Custom size rolls are available upon request.