TECHNICAL SPECIFICATIONS
Galvanized and PVC Coated Steel Gabions
Scope:
This specification data sheet covers the use of PVC coated steel double twisted hexagonal wire mesh baskets filled with stone used for various applications including but not limited to retaining walls, mechanically stabilized soil retaining structures, stream and river bank protection, slope paving, outfall structures, weirs and drop structures etc...
Definition:
a) Gabions are defined as double twisted woven wire mesh box shaped baskets of various sizes and dimensions.
b) The selvedges of the gabion baskets are the thicker perimeter and edge wires to which the wire mesh is secured as to withstand sudden or gradual stress from any direction.
c) Reinforcing wires are the thicker wires incorporated into the netting during fabrication.
d) The diaphragms are internal wire mesh partitions which divide the gabions into cells.
e) Lacing or tie wire is the wire used to assemble and join the gabion units.
f) Connecting wires are the internal wires used to prevent the gabions from bulging.
g) Alternative fasteners are ASTM approved wire fasteners used in lieu of lacing wire.
Fabrication: Double Twisted Hexagonal Steel Wire PVC Coated Mesh Gabions. Gabions shall be fabricated in such a manner that the sides, ends, lid and diaphragms can be assembled at the construction site into rectangular baskets of the sizes specified and shown in the drawings. Gabions shall be of single unit construction: the base, lid, ends and sides shall be either woven into a single unit or edge of these members connected to the base section of the gabion in such a manner that strength and flexibility at the connecting point does not compromise the engineered structural design of the gabion. Where the length of the gabion exceeds one and one half its horizontal width, the gabion shall be divided by diaphragms of the same mesh and gauge as the body of the gabion, into cells whose length does not exceed the horizontal width. The gabion shall be furnished with the necessary diaphragms secured in proper position on the base in such a manner that no additional tying is required at this juncture.
Gabion Specification (PVC) Mesh Formation: The double twisted hexagonal wire mesh shall have deformability sufficient to permit minimum of mesh elongation equivalent to 10% of the unstretched length of the mesh test section without reducing the gauge or the tensile strength of the individual wire strands to values less than those for similar wire, one gauge smaller in diameter.
Non-Raveling: The wire mesh is to be fabricated in such a manner as to be non raveling. This is defined as the ability to resist pulling apart at any of the twists or connections forming the mesh when a single wire strand in a section of mesh is cut.
Gabion Fill: The stone fill material used for filling the gabion units shall be clean, hard stone with pieces ranging from 4-8 inches on the greatest dimensions. Stone filling shall not exceed 24 inch vertical drop above the gabion basket. All effort shall be made to ensure that the stone fill material utilized in the design of the structure match the stone fill used in constructing the gabion structure. Assembling and placing:
a) Each gabion shall be assembled by tying or fastening all untied edges. The binding wire shall be tightly looped around every other mesh opening along the seams in such a manner that single and double loops are alternated. Alternative fasteners may be used in lieu of lacing wire. The alternative wire fasteners shall be applied at approximately 4” to 6” intervals on all vertical seams. No less than 3 fasteners per one foot on any given vertical or horizontal seam.
b) A line of empty gabions shall be placed into position according to the contract drawings. Lacing wire or alternative fasteners shall be used to secure each unit to the adjoining one along the vertical reinforced edges and the top selvedges. An approved corner closure tool shall be used to adjoin adjacent gabions to insure a tight, neat seam and minimize gabion wire joint deformation. The base of the empty gabions placed on top of the filled line of gabions shall be tightly wired or fastened to the latter at front and back. The lid shall be secured with an approved closure too to insure proper closure without excessive mesh deformation.
c) To achieve optimum alignment and finish for retaining walls, a minimum amount of stretching may be required.
d) Connecting wires shall be inserted during the filling operation as follows: Install according to manufacturer’s instructions every 1’ vertical lift of the gabion unit L USUALLY DOUBLE THE LIFE EXPECTANCY OF A GABION INSTALLATION
