Permathene AL-TEN™ Gabion is manufactured in virgin steel to a minimum wire coating of 290 grams per m2 which is Aluminium 10% and Zinc 90%. The mesh is manufactured in Australia to meet gabion specification ASTM 974-97.
Since 2013 we supply this type rather than the standard Galfan Al 5% Zn 95% due to its longer life. Permathene Gabion panels are a product you can trust to meet Australian standards.
Although difficult to predict as lifespan of all steels is largely dependant upon the environment. Generally you can expect 20 years life for galvanised wire, and 2-3 times longer life span for Galfan, AL-TEN™, PVC coated and stainless steel. The wire of AL-TEN™ is given a general lifespan, see table below.
The most popular gauge of wire is 4mm (AL-TEN™) due to the balance of rigidity and appearance. The wire is not very obvious at a distance, especially as it turns grey over time. A 4mm AL-TEN™ wire mesh with a 290gsm coating will still have a 50 year plus life span under moderate conditions and will outlast a 5mm galvanised wire mesh made from standard zinc coated mesh.
|Wire Diameter Tolerance||mm||+/- 0.08|
|Coating Mass (average)||g/m2||333|
|Coating Mass (minimum)||g/m2||290|
|Coating Type (Aluminium / Zinc)||%||Al10 Zn90|
ASTM 974-97 is American Standard Test Method and is the only standard for welded mesh gabions. According to this standard the mesh must meet the following:
|AGGRESSIVITY OF ENVIRONMENT||Al5% Zn95%||AL-TEN|
|C1: Very Low (Internal buildings with clean atmospheres)||100 years +||100 years +|
|C2: Low (Low level of pollution, mostly rural areas)||100 years +||100 years +|
|C3: Medium (Urban and industrial atmospheres, moderate sulphur dioxide pollution, coastal areas with with low salinity)||50 years||93 years|
|C4: High (Industrial areas and coastal areas with moderate salinity)||27.5 years||47 years|
|C5: Very High (Industrial areas with high humidity and aggressive atmosphere, coastal and offshore areas with high salinity)||14 years||25 years|
|CX: Extreme (Extreme industrial areas, coastal and offshore areas with occasional contact with salt spray)||< 5 years||< 10 years|
Expected lifetime for the different coating classes and different corrosivity categories is shown in the table above. Corrosion is a complex issue. Due to the many variables including prevailing wind direction, type and concentration of corrosive contaminants, the amount of sea spray present and the relative periods of moisture or condensation and dryness, only an estimate of expected life can be made in regards to the wire life expectancy. The corrosivity classes are based upon the standard EN ISO 9223.
The mesh life is dependant upon no damage to the coating during installation or during the lifetime of the wall. Because the wire is a coated mild steel any damage to the mesh which removes the Zinc/ Aluminium coating will eventually corrode. If upon inspection damage to the coating is seen or corrosion has occurred it needs to be rectified.
Other considerations when determining lifespan is soil PH levels if the product is placed directly on the earth. A geotextile fabric such as Syntex nonwoven 145gsm may be used as a separation layer. Some rock such as limestone has a high PH (alkaline) which may have a detrimental effect on the mesh.
Rock cleaning or other chemicals including acids and caustic solutions which come into contact with a Galfan, Galvanised, Stainless Steel mesh may have a detrimental effect to metal surfaces and may cause premature corrosion and breakdown at areas of contact. It is recommended to not use any chemicals and to wash immediately with water should contact occur. If exposure to corrosive type chemicals to Zinc and Aluminium is expected alternative systems should be considered following analysis of potential problems. Once corrosion has occurred it may be necessary to apply a rust remover and to then apply either a cold galv or zinc/aluminium paint to affected areas.
Custom aperture (mesh openings) and panel sizes are available although minimums may apply depending upon requirement. Generally 2-3 weeks for delivery.