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Why earth stabilisation should be re-thought, reinforced and retained


Posted by PlantMiner

A commercial and infrastructure project has one unpredictable nemesis: heavy rainfall. Unluckily, 2015 has ushered in some torrential rainfall events for job sites lining the South East coast of Australia. For earth stabilisation projects, engineered retaining walls have never been more important.

To lend a hand, we caught up with Martin Silec, Managing Director of Concrib, whose company boasts over 30 years of experience designing and constructing the highest possible standard of engineered retaining walls.

Our philosophy is based on offering our clients the most appropriate, best engineered, value for money, retention solution applicable to their particular situation. To distinguish which service or products offer true value for your money, it becomes important to investigate how well they comply with Australian standards reflecting design and product requirements - Martin Silec, Managing Director of Concrib

When it comes to selecting the best retaining structure for your project, the process can be difficult. The balance between cost and quality can seem insurmountable.

Be they concrete, concrete masonry, reinforced concrete or steel, all engineered retaining wall products must comply with Australian standards. Unfortunately, as the Australian dollar continues to decline, the monitoring of materials and construction techniques have become increasingly lax. A number of overseas importers have jumped on the bandwagon and the earth stabilisation industry is starting to see the effects of overlooking criteria.

It is extremely disappointing to find that in many projects, the design and/or supervising engineers too often certify construction activities without ensuring that the products used in that activity do in fact meet Australian Standards - Martin Silec, Managing Director of Concrib

When shortcuts are taken, problems may not manifest for years, or may strike when the structure is put under stress, such as incidences of flood or high rainfall. This can involve very costly remediation work - which can be magnified if the problem flows on to affect nearby buildings and structures.


Screen Shot 2015-05-15 at 9.42.19 am Before: Bellthorpe Range Road damaged in the 2011 floods


Screen Shot 2015-05-15 at 9.33.31 am After: by reconstructing Bellthorpe Range Road and installing gabions, Concrib has made the mess of rockfalls and pavement failures into a safe and resilient road.


Martin quickly set us straight about the key standards any civil/building contractor, government authority, consulting engineer or architect should implement.

AS4678 The Overall Standard for Australian Retaining Walls

Wall design and construction must be compliant with AS4678 Earth Retaining Structures code. This policy addresses a number of important issues, including design life, durability and fitness for purpose.

AS3600 Concrete Structures

Products must be manufactured to meet the standards of AS3600 Concrete Structures. This policy sets out minimum requirements for the design and construction of concrete structures that contain reinforcement steel, or tendons, or both. Major points addressed in the standard relate to design methodology, durability, strength, climatic conditions and cover. Concrib's manufacturing processes and products are inspected and certified (Form 16) on a monthly basis to confirm compliance. You should ask questions like:

  • is the strength of the concrete correct for the application?
  • what is the required depth of cover for reinforcing, to ensure strength and protection from possible future 'concrete cancer' problems?

Concrib makes sure that every project they complete is done properly - and so should you.

AS4680 Galvanised Coatings

Important points covered in this standard relate to appropriate coating thickness and mass per unit area of zinc coasting and coating adherence. These properties dictate the durability and design life of the galvanised steel article for particular applications. Typically, these coatings need to have a 500-600 gram mass per unit area and 65-85 micron thickness. There is a major difference in the quality of coating adherence between low-quality galvanised steel products and high-quality products.

AS4100 Steel Structures

AS4100 sets out the minimum requirements for the design, fabrication, erection and modification of steelwork in structures. So when working with steel reinforcing, it's important to consider quality. Therefore the strength and bar diameter are paramount. Equally important is the way the steel has been treated, for example zinc coating must comply with AS4680. If the product does not meet the standards for steel quality or galvanisation, exposure to water and salt spray can lead to significant repercussions.


Screen Shot 2015-05-15 at 9.26.41 am Concrib’s sleeper wall Saddlers Ridge, Gilleston Heights, NSW


AS3700 Masonry

This standard sets out minimum requirements for the design and construction of masonry, including unreinforced, reinforced and prestressed, using manufactured units of clay, calcium, silicate and concrete laid in mortar, autoclaved aerated concrete laid in thin-bed mortar, and square-dressed natural stone laid in mortar.

The certifying engineer should always ensure that the structural design complies with the code, as well as the chain of supply used to fabricate or manufacture the wall components.

When making your choice, don't simply accept a claim of 'compliant with Australian standards' at face value. Call in the professionals at Concrib and ensure that your retaining walls are built with the most durable, state-of-the-art materials and are fully compliant with relevant legislation.

We give you real value and quality for your money by offering the design, supply and installation for any earth stabilisation need. Concrib analyses every specific retention system and uses 30 years experience to put forward the most appropriate solution. - Martin Silec, Managing Director of Concrib

Proving they're at the top of their game, Concrib have nabbed a Category 1 2014 Award from the Civil Contractors Federation (CCF) QLD annual Earth Awards after being a finalist for many years. But most importantly, they operate a Quality Management System compliant with ISO9001:2008 which ensures the supply of all relevant documentation regarding certificates for structural steel, concrete, galvanising, reinforcement etc.

For your protection, Concrib have already designed a checklist criteria. We recommend you give them a call on 1800 021 800 so you can make your choice with confidence.

It pays to make sure that all the links in the chain meet Australian Standards.

You should know that this post is sponsored by Concrib, however all opinions are our own.



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