Teranap is resistant to puncture failure

When a geomembrane is applied over a surface with stones or protrusions and subjected to a high load, the ability to resist puncture is critical.

The viscoelastic nature of bitumen combined with the tensile strength of its non-woven reinforcement geotextile layer means Teranap can deform to accommodate high point loads, therefore resist being punctured.

The bitumen's viscous properties allow small adjustments under pressure, while its high cohesion means small penetrations are 'self sealed'

On most geosynthetic product datasheets there will be a value for puncture resistance according to ASTM D4833.  It is important that the meaning of this value be understood before any assumptions about a product's puncture resistance are made.  The standard clearly states that this is an 'index test' intended for manufacturers to quickly test the quality of their product - it was never intended as a value to be used in design.  

A better understanding of how a particular geomembrane will cope in real applications is to consider its tensile curve, in particular the yield point and the work done (energy absorbed) under the curve.

Even though the force at yield is similar - about 2000N - the area under the graph (the work done to deform the material to yield) for Teranap 331 (3.3mm) is much greater than for the 2.0mm HDPE. 

The ability of Teranap to resist punctures means a cushion or protection layer above or below the ground is usually unnecessary, saving time and money for a project.

 

With a plastic lining system, most manufacturers require a geotextile protection layer to accompany the plastic geomembrane. This is often a hidden cost.

When a material 'yields' it undergoes permanent irrecoverable deformation. The graph below shows that  Teranap 331 (3.3mm) requires three times the effort to make it yield compared to 2.5mm HDPE. 


Picture Picture

Puncture test on bitumen membrane laid over 56 mm without protection layer, 2" minus material. The geotextile prevents the coarse bedding material from puncturing through the membrane. And as the geotextile reinforcement was completely impregnated in bitumen, the membrane remains water tight.