Synergisms between laboratory mechanical and abrasion damage on mechanical and hydraulic properties of geosynthetics

• Laboratory damage tests were performed on a geotextile, a geogrid and a geocomposite.
• Abrasion damage was the most important mechanism for the tensile response.
• Mechanical damage was the most important mechanism for the hydraulic properties.
• Positive synergy between mechanical and abrasion damage for the tensile properties.
• Traditional approach for estimating hydraulic properties is likely unsafe.

This paper analyses the existence of synergisms between some endurance durability agents of geosynthetics – mechanical damage (usually associated with installation) and abrasion damage (often associated with cyclic actions, for example due to contact with ballast). Three geosynthetics (geotextile, geogrid and geocomposite) were submitted to mechanical damage and abrasion damage using index laboratory tests. The geosynthetics were exposed first individually to each agent (single exposure) and then sequentially to the two agents (multiple exposures). To ensure the results were statistical representative, each set of tests was performed three times. The consequences of the damage induced were visible (naked eye). Abrasion damage was found the most critical damage mechanism for the tensile properties, particularly for the geogrid and geocomposite tested. The connections between their components created potential fragility points in the abrasion test. Due to its structure, combined with high mass per unit area and thickness, the geotextile tested survived well the damage induced. A positive synergy between the mechanical and the abrasion damage induced was found for the tensile properties of the geosynthetics most affected by damage, more important for their tensile strength than for their secant stiffness. The mechanical damage was the most critical mechanism for the permittivity of the geotextile and the geocomposite, likely due to clogging of their pores. For the permittivity and the characteristic opening size of these geosynthetics, negative synergy between mechanical and abrasion damage was found; the traditional approach was found likely to result in unsafe estimates of these properties.