Seam CQA Tests

Who say measurements of shear and peel strengths provide no useful information? At a recent meeting Rick Thiel (Thiel Engineering) informed Ian Peggs (I-CORP) that he had started using and specifying only peel separation and shear elongation in geomembrane seam CQA tests, as proposed by Peggs for a number of years. Thiel agrees that measurements of shear and peel strengths provide no useful information. Peggs has shown (EuroGeo 1) that when weld efficiencies exceed only 8% for 1 mm geomembranes and only about 18% for 2.5 mm geomembranes the weld interface cannot be challenged since failure always occurs prematurely in the single thickness of geomembrane at the edge of the weld, due to its relatively low cross sectional area.