PVC Coated Gabion Boxes and Geotextile Filter Required

1. Gabions
   Gabion boxes materials: mesh, selvedge and lacing wires shall be galvanized and PVC coated and shall confirm to the following standards.
   
   PVC coated gabion box panels.
   • Wire: B.S.1052/1980.
   • Galvanizing: B.S. 443/1982.
   • PVC coating: ASTM D 4/2.
     1. Mesh: PVC coated gabion boxes shall be with hexagonal mesh opening 80mm × l00 mm manufactured of triple twisted steel wire of minimum 2.5 mm dia. with a heavy zinc coat followed by a PVC coating with final minimum outside dia. 3.4 mm and internal diaphragms at 1 m center spacing satisfying the above standard.
     2. Selvedge wire: Steel wire of a minimum diameter of 3 mm. with a heavy zinc coat followed by a PVC coating with final minimum outside diameter 3.9 mm satisfying the above standard.
     3. Lacing wire: Steel wire of a minimum diameter of 2.5 mm. with a heavy zinc coat followed by a PVC coaling with final minimum outside diameter 3.4 mm satisfying the above standard.
     Note: The material for the gabions may be of equivalent or higher strength and durability In relation to the above specification.
   Rubble: rubble for filling baskets shall be of sizes varying from about 100 mm to 200 mm in maximum dimension, and they shall be hard and durable, free from weathered pieces.
2. Geotextile requirement - 4500 sq.m
   Geotextile filter
   • General: the space behind the gabion box in contact with soil shall be covered with geotextile filter material in accordance with specification given below and as shown in the drawing to allow passage of water while preventing loss of soil particles. Overlapping of geotextile fitter shall be done properly with minimum of 150mm overlapping and knitted with a suitable material.
   • Material: the Geo-textile filter doth shall be of approved filter of none woven fabric composed of polyester, polypropylene, or a combination of the above. The geotextile shall have the following properties.
     1. Thickness: 2.5 mm (Min.)
     2. Tensile strength (wide strip): 10 kN (Min.)
     3. (ASTM D4595, BS 6906 - 1, AS 3706 -2).
     4. Pore size: 0.15 (Max.)
     5. Water permeability: 80 lit./sec./m².
3. Backfill behind gabions: backfilling behind gabions shall be carried out with approved sandy - gravel material.

PVC coated gabion boxes with triple twisted hexagonal mesh in the river bank construction site.