To mobilise the granular interlock necessary for a geogrid to perform its reinforcement function the sub-grade must be able to lock up against the ribs of the geogrid and transfer load into the geogrid. A higher vertical rib provides a greater surface area and hence more effectively transfers the stresses.
From this, it follows that products with a lesser rib height will transfer the stresses less effectively. It is believed that products having lesser rib heights can actually twist / buckle in the soil such that they do not remain flat as intended. Such an occurrence would have a significant adverse effect on performance. E’GRID geogrids have been designed to optimise the rib height when the polymer sheet is punched and drawn.
The sections above show the machine direction (MD) and transverse direction (TD) ribs of E’GRID (prefixed S) and Triax (prefixed T) geogrids. The diagrams show that both types of geogrid have good rib height and will hence give efficient load transfer.
The left-hand diagram compares E’GRID 2020 and Triax TX160. Both have similar rib forms so it can be assumed they would perform in a similar manner.
The right-hand diagram compares E’GRID 3030 and Triax TX170. Here it can be clearly seen that the E’GRID 3030 has a significantly greater rib height so it can be assumed the product would provide superior performance.
Given the importance of rib height to a product's performance this measure should be included in a geogrid specification.