The researchers developed a new lab apparatus to test how geosynthetic materials behave under pressure and heat. They found that traditional tests for geosynthetics are costly and time-consuming, and don't consider the impact of soil confinement. The new device allowed them to conduct faster tests that mimic real-world conditions more accurately. They discovered that some geosynthetics are affected by soil pressure, while others are not. This shows the importance of understanding how soil confinement affects the behavior of geosynthetics.