6.3 Reinforcement products
6.3.1 General
6.3.1.1 Fill reinforcements can be made from metals, generally steel, or polymeric materials. See Annex D for some typical examples.
NOTE Fibre glass and carbon fibre reinforcement has been used experimentally and natural fibres have been used in temporary structures.
6.3.1.2 Reinforcement shall only be used if its suitability, including durability, has been proven by trials, or experience, and by approved tests, carried out on the product or on a similar product of the same class of material and whose properties are known to be equivalent, to ascertain that the requisite properties of the reinforcement are likely to be available at the end of the specified design life in the design operating conditions.
6.3.1.3 All fill reinforcement products shall conform to the specification for the works as required by the design.
6.3.2 Steel fill reinforcement
6.3.2.1 Steel reinforcement (Figure D.1) may take the form of either strips, bars & rods to EN 10025-4, EN 10025-2 or EN 10080, ladders, welded wire meshes (also known as grids, or bar mats) to EN 10080 or woven wire meshes to EN 10218 and EN10223. They should generally have one end connected to a facing, at spacing prescribed by the design. Steel reinforcement may be provided with a protective coating to mitigate the effects of electro-chemical corrosion. Some typical examples of widely used steel reinforcements are considered in Annex E.
6.3.2.2 Steel strips, rods, bars, ladders or welded wire meshes may be provided with a galvanizing coating. The galvanizing shall conform to EN ISO 1461 with a local coating thickness of 70 µm. Thin strips may be galvanised in accordance with EN 10326, with a local coating thickness of 35 µm. A corrosion allowance shall be applied to the base metal appropriate to the design life.
6.3.2.3 Steel woven wire meshes may be provided with a zinc-aluminium alloy coating (Zn95Al5), minimum 30 µm thick further protected by a 0,5 mm thick PVC or PE coating. The zinc-aluminium coating shall conform to EN 10244-2.
6.3.2.4 Stainless steel or aluminium alloys should not be used for soil reinforcement in permanent structures unless for particular cases and based on specific studies.
6.3.3 Polymeric reinforcement
6.3.3.1 Polymeric reinforcement can take many forms, (Figure D.2), such as strips, grids or sheets which may not be connected to a facing. Like steel strips, polymeric strips shall be installed at predetermined vertical and horizontal spacing required by the design. In contrast, only vertical spacing shall be specified for grids or sheets installed as full width reinforcement. The most commonly used polymers are polyester and polyolefins, although other geosynthetic materials may be used.
6.3.3.2 All geosynthetic fill reinforcement shall conform to the requirements of EN 13251, as far as tests and testing procedures are relevant in regard to the particular form of the reinforcement.
6.3.3.3 As required by the design, polymeric fill reinforcement in the form of strips, grids or sheets shall be provided with certified values of design strengths pertaining to the specified design life and operating temperature of the reinforced fill structure and, based on tensile creep rupture and isochronous load-strain characteristics per EN ISO 13431.
6.3.3.4 Unless they are based on previous relevant experience and/or specific testing as per clauses 6.2.8.2, 6.2.8.4 or 6.2.9.2, the certified values of the design strengths of polymeric fill reinforcement shall be based on construction induced damage as ENV ISO 10722-1, fill reinforcement interaction as EN ISO 12957-1, and durability as EN 13251, Annex B, including a consideration of resistance to weathering per EN 12224 and possibly of microbiological attack per EN 12225.
