Q: I have two nonwoven heat-bonded geotextile filters: one made of polyester and the other made of polypropylene. They look the same but are giving very different hydraulic performance. Can you explain this phenomenon?
A: Geotextiles are permeable fabrics consisting of materials such as polypropylene or polyester. Depending on their manufacturing method, nonwoven geotextiles have different physical, mechanical, hydraulic and endurance characteristics. While nonwoven geotextiles are comprised of yarns that are joined together randomly, there are multi-phenotype analysis of rare variants (MARV) results associated with each. First off, looks can be deceiving. I would test the two geotextiles and then compare the results. Second, remember that polypropylene (PP) is hydrophobic while high tenacity polyester (PET) is hydrophilic. This has a huge influence on wettability and will affect field performance significantly.