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

A method of making a multilayer integral geogrid, 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 said plurality of layers having an expansion structure capable of forming a cellular structure in said 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 oriented strands interconnected by partially oriented junctions, and to configure the holes or depressions as grid openings,
• said first and second outer layers having a cellular structure.

A multilayer integral geogrid comprising:

• a plurality of interconnected oriented first strands and partially oriented junctions forming a repeating pattern of outer hexagons having an array of openings therein;
• each of said outer hexagons supporting and surrounding a smaller inner hexagon having oriented second strands,
• said oriented first strands and said partially oriented junctions of said outer hexagon forming a plurality of linear strands that extend continuously throughout the entirety of the multilayer integral geogrid,
• said integral geogrid having a plurality of layers each of a polymeric material extending throughout said geogrid, and
• at least one layer of said plurality of layers having a cellular structure.