Abstract: In order to provide wider biaxially-stretched geogrids having high primary direction (PD) strength, crotch-forming zones of a starting material which is at least 2.0 mm thick have protuberances (6). On strectching, PD orientation passes right through the junction (27) but the protuberance (6) causes the orientation ratio of the crotch edge to decrease significiantly as orientation enters the central part of the crotch edge. After a secondary direction stretch of at least about 1.5:1, the thickness of the central part of the crotch edge is not reduced by more than about 20%. The stretching does not reduce the thickness of any point along notional ridge lines (31) to such an extent that the ratio of finished thickness to starting thickness at that point mid-point. In the biax geogrid (25), the junction mid-point is significantly thicker than the PD is less than about 80% of the ratio of finished thickness to starting thickness of the junction strand mid-point.

Abstract: A retaining wall for reinforced infill material of the type comprising superimposed courses of modular blocks, each block having a front face, a rear face, parallel upper and lower faces, and opposed sidewalls which extend between the upper and lower faces. Reinforcement material extends back from the wall into the infill material with an end portion of the reinforcement material interposed between two superimposed coursed of the wall and anchored to the wall by an anchor element which is retained in a retaining cavity between contiguous upper and lower faces of blocks in the superimposed courses. The anchor element has a spine which is of wedge-shaped cross-section for at least part of its length and has a plurality of spaced-apart projections extending from one side there of and engaging through apertures in the reinforcement material.

Abstract: In order to laminate a fabric to a plastics material grid formed of oriented strands connected by junctions having thicker and non-oriented or less-oriented nodes, the fabric and the grid having the same melting temperature, the grid is heated by a drum to melt the surfaces of the nodes, and the grid and the fabric are passed through a nip formed by nip rollers, the fabric having been pre-heated by passing around a preheat roller. One nip roller has surface protuberances formed by knurling of such a size that a number of protuberances engage (by way of the fabric) each node of the grid.

Abstract: Cooling an extruding thermoplastic tube by feeding the tube adjacent a cooling surface, maintaining a sheath of heat-transfer fluid between the tube and surface and preferentially cooling at least a selected area of the tube by transversely displacing the tube to decrease the thickness of the sheath between the selected area and the cooling surface. The invention is particularly suitable, for the production of thermoplastic films by orienting a cast tubular extrudate which has been cooled by means of an internal mandrel.

Abstract: Cooling an extruding thermoplastic tube by feeding the tube adjacent a cooling surface, maintaining a sheath of heat-transfer fluid between the tube and surface and preferentially cooling at least a selected area of the tube by transversely displacing the tube to decrease the thickness of the sheath between the selected area and the cooling surface. The invention is particularly suitable, for the production of thermoplastic films by orienting a cast tubular extrudate which has been cooled by means of an internal mandrel.