Abstract: A starting material is provided having a rectangular grid of holes and the starting material is stretched in the MD to such an extent that the junctions are not significantly oriented, is stretched in the TD to such an extent that the junctions are not significantly oriented, and is finally stretched in the MD to such an extent that the junction centres thin down by at least 30% and there is significant narrowing down of the junction The resultant MD stretch is substantially greater than the resultant TD stretch. The MD strands, having thinned down and oriented to a substantial degree, cause the orientation to pass into the ends of the junctions and right through the junctions. The junctions increase in length by a ratio of at least about 2.5:1 and narrow down substantially. The ends of the junctions are not stretched more than 100% more than the centres.

Abstract: A starting material is stretched longitudinally to produce a geogrid. The starting material has pronounced ribs on each face, merging into sloping sides. Between the ribs, there are holes on a square grid. The mean thickness of the longitudinal elements is substantially greater than the mean thickness of the interconnecting elements, and the cross-sectional area of the longitudinal elements is at least 2.5 times the transverse cross-sectional area of the interconnecting elements. The longitudinal elements are stretched out into continuous oriented strands. The centers of the junctions reduce in thickness by at least 10% but substantially less than the percentage reduction at the thinnest part of the strand.