Geomembrane Comparisons: Why Thicker Is Not Always Better

Bill Shehane on Jan 4, 2017 8:00:00 AM

4S San Diego white XR-5 (install)There are many misconceptions across the geomembrane industry about what constitutes an optimally manufactured geomembrane. One of the most prominent relates to their required thickness, which often leads to a common topic of deliberation among geomembrane experts and engineers: “Is a thicker membrane actually better?”

The Status Quo

A typical geomembrane has the consistency of a thicker garbage bag and is measured to be 60 mils thick. This material, known as 60 mil HDPE, is the industry standard. Many engineers are conditioned to believe that a thicker geomembrane will be a better geomembrane, which is not always the case.

The XR® Geomembrane

Engineers are generally impressed with the chemical and UV resistance that XR geomembranes provide, but often request the geomembrane be 60 mils thick rather than 30 mils, which is thin for a geomembrane. The reason the typical XR Geomembrane material used for lining projects is 30 mils thick is because they’re enhanced with an internal reinforcing base fabric that adds extreme strength and puncture resistance. By comparison, unreinforced  geomembranes such as HDPE become incrementally more puncture resistant with increased thickness. The difference is in the unique manufacturing process of XR Geomembranes—it’s what allows them to be thin but extremely durable.

Tensile Strength and Puncture Strength

The tensile strength of an XR Geomembrane is mainly influenced by its base fabric or “scrim”. A typical HDPE geomembrane can stretch up to 200–300 percent, while the XR Geomembrane will only stretch up to 20–25 percent. The HDPE geomembrane yields very quickly, where as a reinforced product such as an XR Geomembrane takes a much higher tensile load where both the yield and breaking point are around 25% elongation.

Life Expectancy and Environmental Stress 

One would think a thicker geomembrane would have a longer life expectancy. In reality, the thickness of a geomembrane has little impact on its life expectancy. The actual lifespan of a geomembrane is more dependent upon its strength and manufacturing process. And when it comes to environmental stress, many conclude a thicker geomembrane is a better choice. However, the XR-5 Geomembrane is more puncture resistant and less likely to succumb to wear and tear.

Puncture Pack Proof

The facts and numbers behind this geomembrane thickness dispute are crucial when evaluating and comparing geomembrane materials. However, having physical proof that supports this “less is more” mentality is much more effective when demonstrating the ultimate strength of the XR Geomembrane. This is why XR Geomembranes developed a puncture pack that includes three samples of different geomembranes: a 60 mil HDPE sample, a 45 mil Polypropylene sample and a 30 mil XR-5 sample.

When choosing between the three geomembranes, the puncture pack’s physical demonstration of the XR Geomembrane’s superior tensile and puncture strengths can ultimately prove that a thicker geomembrane is not always the better choice for your needs.

What other factors do you consider when comparing geomembranes? Tell us about them in the comments! XR-5 vs HDPE

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