Multilayer integral geogrids having a cellular layer structure, and methods of making and using same

A method of making a multilayer integral geogrid for interlocking with, stabilizing, and strengthening a soil or aggregate, said method comprising:

• providing a multilayer polymer sheet having a plurality of layers each of a polymeric material, with at least a first outer layer and a second outer layer of the plurality of layers having an expansion structure capable of forming a cellular structure in the first and second outer layers of the multilayer integral geogrid;
• providing a patterned plurality of holes or depressions in the multilayer polymer sheet;
• and
• biaxially orienting the multilayer polymer sheet having the patterned plurality of holes or depressions therein to provide a plurality of interconnected oriented strands and partially oriented junctions forming a repeating pattern of outer hexagons having an array of openings therein,
• supporting ribs extending inwardly from each of the outer hexagons to support inside each of the outer hexagons a smaller inner hexagon having an open center and oriented strands and tri-nodes, each of the tri-nodes interconnecting only one of the supporting ribs and two of the oriented strands of the inner hexagon,
• the outer hexagons, the supporting ribs and the inner hexagons defining three different geometric configurations which are repeating throughout an entirety of the integral geogrid, and
• the oriented strands and the partially oriented junctions of the outer hexagons defining a plurality of linear strands that extend continuously throughout the entirety of the integral geogrid,
• so as to provide the biaxially oriented integral geogrid with at least a first cellular outer layer and a second cellular outer layer configured to improve an initial interaction between, and compatibility of the soil or aggregate with, the integral geogrid, so as to maximize soil or aggregate density and properties after compaction.