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What is a gabion?
The gabion is a box shaped element manufactured from hexagonal double twisted steel wire mesh and filled on site with hard wearing, durable rocks of suitable dimension. The box shaped gabion elements are connected together to construct the gabion wall or other installation.
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What are the characteristics of the wire used to make the gabion mesh?
Gabion mesh is made from soft annealed steel wire which is additionally coated to increase its durability and design life. The coatings include: zinc galvanized, Galfan (a eutectic Zn-Aluminum (5%) MM alloy); zinc galvanized with PVC coating.
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Where gabions and gabion walls are used?
Gabions can be used in many ways, including: retain unstable slopes; provide erosion control to rivers, channels and shorelines; create acoustic barriers; dressed architectural buildings and many other applications that require a permeable, flexible, durable and very cost effective structure.
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What type of rock fill is recommended for gabions?
Gabion rock fill should be hard, durable, dense and non-frost susceptible, with a dimension of 4-8” diameter. A ‘block’ shaped rock will be easier to install, and produce a better finish than a rounded ‘cobble’ shaped rock. To maximize the mass of the structure, it is necessary to minimize the void volume of the fill within the gabion unit. i.e. more rock, less air. We do not recommend that smaller rocks be used as they will fall through the apertures in the mesh. However, there are certain specific circumstances when smaller rock can be used. The range in sizes may allow for a variation of 5% oversize and/or 5% undersize rock, provided it is not placed on the gabion exposed surface. Our ‘Product Installation Guide” for gabions provides further detail.
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How can I calculate the amount of rock needed for my project?
Gabion rock fill is generally supplied by the ton. Depending upon the density of the rock fill at your local quarry, the final tonnage you order will vary. As a rule of thumb, gabion rock fill is going to be around 1.4 -1.5 tons per cubic yard. This would allow for overfilling of units and some wastage. It assumes that the gabion is 25-35% voids, and that the density of good rock fill is 155lb/CUft.
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ASTM Specifications
Double Twisted Hexagonal Mesh Gabion Baskets and Mattresses have been used world wide for retaining wall, slope stabilization, channel lining, rockfall protection and many other applications for over 100 years. Due to the low cost long term solution double twisted mesh gabions provide for these applications their usage has become common place with many Government Agencies, and Private Land Developments etc… here in the United States. As gabion usage grew domestically the requirement for an industry standard of product quality became vital to ensure material consistency. The AMERICAN SOCIETY OF MATERIALS AND TESTING has long been recognized as requiring high quality standards and assisting industries in establishing an industry standard for specific materials and products. The AMERICAN SOCIETY OF MATERIALS AND TESTING (ASTM) publishes a specification book which documents each specification in its entire format. Each individual product specification within the ASTM book is designated a specification number for reference. The ASTM specification number for Double Twisted Hexagonal Mesh Gabions is ASTM A975-97.
The full version of ASTM A975-97 specification is not shown in its entirety. The performance requirements of the finished product and the material data information are represented.
STRENGTH REQUIREMENTS
ASTM A 975-97
MINIMUM STRENGTH AND PERFORMANCE REQUIREMENTS OF DOUBLE TWISTED HEXAGONAL MESH GABIONS
TEST DESCRIPTION |
GALVANIZED/GALFAN GABION |
PVC COATED GABION |
Tensile strength of wire mesh parallel to twist |
3500 lbs/ft |
2900 lbs/ft |
Tensile strength of wire mesh perpendicular to twist |
1800 lbs/ft |
1400 lbs/ft |
Connection to selvedges |
1400 lbs/ft |
1200 lbs/ft |
Panel to Panel |
1400 lbs/ft |
1200 lbs/ft |
Punch strength of mesh |
6000 lbs/ft |
5300 lbs/ft |
MATERIAL REQUIREMENTS FOR GALVANIZED DOUBLE TWISTED HEXAGONAL GABIONS
| Diameter of mesh wire |
0.120 inches |
Diameter of selvedge wire |
0.153 inches |
Diameter of lacing wire |
0.091 inches |
| Coating of wire |
Finish 5 class 3 zinc coating ASTM A-641 tested in accordance with ASTM A370-92 |
| Tensile of wire |
54,000-70,000 psi soft temper accordance with ASTM A641-92 |
Weight of zinc coating of wire |
Determined by ASTM A-90 |
Mesh opening size |
8x10cm or 3.25inches x 4.50inches |
Mesh wire 0.120 inches |
Weight of zinc coating 0.85 oz/sf |
Selvedge wire 0.153 inches |
Weight of zinc coating 0.90 oz/sf |
Lacing wire 0.091 inches |
Weight of zinc coating 0.80 oz/sf |
Grade of zinc coating of wire |
High grade or special high grade in accordance with ASTM B-6, Table 1 |
Uniformity of coating of wire |
Determined by ASTM A-239 |
| Elongation |
Not less than 12% in accordance with ASTM A370-92 |
All of the above wire diameters are subject to a tolerance limit of 0.004 in accordance with ASTM A-641. TOLERANCES: All gabion dimensions shall be within a tolerance limit of plus or minus 5% of the manufacturers stated dimensions. |
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