As ground-strengthening products, Geocells undergo rigorous testing before sale and installation to ensure they can perform according to their purpose. They must comply with recognised ISO and EN standards.
Geocell Testing Methods
There are a number of testing procedures used for Geocells before they go on sale. The tests depend on the intended functions of the Geocells, whether it is to increase ground load capacity, soil stabilisation, or erosion control.
Junction Strength Testing
Junction strength testing is classed as one of the most important tests of Geocell behaviour. It examines the strength of their internal junctions, where the Geocell strips meet, according to the UK/European Standard BS EN ISO 13426-1:2019. For this process, the test specimens are typically cut into an ‘X’ shape so that the junction is in the centre. This allows the test machine to apply a load in a way that simulates real-world stresses to check for structural failures and deformation. Once the results are acquired, they are used to assess how strong the welded Geocell walls are under a variety of stress conditions.
Tensile Strength of Cell Wall
The tensile strength test assesses the geostrip itself rather than just the junction. Typically, a wide-width tensile test is conducted, which can also be applied to other geosynthetic materials. This test type applies tensile stresses to provide a measure of how much load support the geocell retaining walls can offer before yielding or breaking. If deformation occurs under the load, it means the geocell can’t distribute stress adequately, and it won’t be able to offer soil stabilisation.
Durability Testing
Geocells must be hard-wearing to ensure consistent performance and cost-effectiveness. They must be able to resist UV degradation, oxidation, moisture and other potentially damaging factors.
For thermal resistance, materials such as HDPE, are placed in a forced-air oven at high temperatures of between 70-90 degrees. Following this exposure, the samples undergo tensile testing to check retained strength, as well as oxidation induction time (OIT) tests. Samples are also loaded at constant stress which is sustained for many hours. Temperature and humidity are controlled to assess geocell performance over time following load transfer.
Field Performance Testing
During these performance tests, geocells are installed in a test bed. There is controlled subgrade stiffness to assess whether geocell reinforcement is provided in a more authentic environment. Cyclic plate loading tests are applied to the geocell-reinforced bases via a loading plate. The temporary or permanent deformation of the sample is measured, and vertical stress sensors can be placed at different depths. For example, either above, in the geocell layer, or at the subgrade. This is to assess how the load is transmitted, enabling engineers to get a clear picture of how well the geocells are able to spread the load, reduce subgrade over-stressing, and control deformation in a real situation.
Our Test Standards for Geocell Reinforcement Products
Made from High Density Polyethylene, our Terram HDPE Geocells are all supplied having met internal quality requirements in compliance with our Quality Management System, which is certified to BS EN ISO 9001:2015. They have also been thoroughly tested to meet UKCA certifications. These tests include checking geocell strength performance, durability, soil interaction, and dimensional checks.
For more information about our geocells and how they are tested, feel free to get in touch with a member of our knowledgeable team.
