Australia built in stepped concrete with great success!

AUZCON-Stepped Precast Wall
Introduction
The requirement for a flexible, durable, easily built, long life span, functional, but reasonably cost solution to retaining coast-line areas has been a perplexing challenge for Engineers within Australia and World-wide. This aligned with variable ground and climatic conditions from both land and sea also creates a need for a resilient and multi-purpose product that can be constructed in diverse locations.
The client, Morten Bay Regional Council (MBRC) accepted a Design-Build type contract for Bongaree Beach, Bribie Island, South-East Queensland sea wall-walkway. Auzcon was successful in winning this contract on their design.
Based on years of expertise and a client requirements, a solution was developed to meet the challenge of the coastal scenario provided. The design has been widely acclaimed and is now patented. This brief provides details about the Bongaree Beach retaining wall that is now successfully completed.seawall-auz-2
Bongaree Seawall-walkway nearing completion October 2014
Key Advantages of the Auzcon Design
 Increased safety at water interface-–no need for a top balustrade. Steps easy to install at a low cost
 Assists prevention of erosion. Installation immediately protects the foreshore
 Environmental sustainable – Generally no wet concrete on site
 High standard and flexible styles of finish with multiple colour options
 Flexible building system
o Suits different layouts/wall heights and easily adapted to different foundation requirements
 Multi use- retaining wall, seating, steps and access
 Portable system suited for constrained sites
 Fast mobilisation and easy to install
 No formwork and other construction false work required – beach stays clean of general building tools and equipment
 Low installation and reduced cartage cost
 High Wave energy dissipation. Wall forms a heavy integrated monolithic stressed together structure that can absorb wave energy from storm events
 Stepped precast elements can be built and constructed on site
 Utilises local material and resources
 Suitable for a wide range of situations
 Flexible foundations designed for specific site requirements
 Wall can be raised easily and at a low cost-just bolt on the next step
 Wall can be placed for emergency repair and can be 100% recycled if it needs to be demolished and rebuilt. This means the only additional cost will be labour and plant

AUZCON-Stepped Precast Wall
Photo Sequence of Wall Manufacture and Constructionseawall-auz-3

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AUZCON-Stepped Precast Wall
Comparison between a traditional vertical and AUZCON 10.20 stepped wall

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Table 1-Comparison summary
It is clear from Table 1 that the AUZ 10.20 sea wall will have a long and useful lifespan giving additional scope to local residents and a long life asset.

AUZCON-Stepped Precast Wall
Construction and Design Flexibility
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Some examples of construction flexibility in terms of steps, hand rails, drainage outfall pipes, seating, colour and texture.
Performance in Adverse Conditionsseawall-auz-17
Comparison of wave dissipation between a vertical and stepped wall
 In the foreground is a stepped wall and in the background is a vertical wall.
 It is clear that the stepped wall is a more efficient in dissipating the wave energy.
 A sloped wall will be the worst dissipater, as the wave will keep on continuing up the slope.

AUZCON-Stepped Precast Wall
Construction
 The wall is comprised of one type of precast block and SS stressing rods.
 A standard precast block is generally 6 m long and gives a 300 mm riser and a 600mm going after installation. Each block weighs approximately 4.2 ton.
 Blocks are generally laid in stretcher bond configuration with 4 stressing rods per block.
 Corners are formed by special cast corner blocks so that they match in with the rest of the wall in stretcher bond
 The same system can be applied for most walls which means stock can be kept for fast mobilisation/installation.
 Ideal for emergency repair. It can later be removed and 100% material recyclable.
 Small footprint in construction.
 A wall can be completed in short sections, reducing the risk of storm and wave damage.
 A team of 4 can install approximately 14 blocks a day. That equates to 10m x 2.4m high wall completed per shift.
 Stainless steel stressing rods are used to eliminate erosion issues
Plans
 Plans are standard for each wall.
 Different foundation types has been identified and designed for the stepped wall.
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Foundation Types
 On rock: Under 1200mm from design lower step – mass concrete
 In sand: Condition sand with grout injection, or CFA piles with or without reinforcement, SS screw piles or CFA piles with pile cap beams. Scour protection by vinyl sheet piling

AUZCON-Stepped Precast Wall
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AUZCON-Stepped Precast Wall
Case Study Stronger Seawall for Bongaree
Bribie Island’s Bongaree seawall, damaged by a one-in-20 year storm surge last year, is being rebuilt to a stronger standard thanks to the Newman Government’s Betterment Fund.
Inspecting the $3.3 million project today, Community Recovery and Resilience Minister David Crisafulli said $1.9 million was coming from the Betterment Fund to extend the seawall and make the esplanade more resilient.
“The $80 million Betterment Fund is part of our strong plan to build a more resilient Queensland,” Mr Crisafulli said.
“The Bongaree esplanade is one of the attractions that make Bribie Island so special.
“The storm surge from ex-Tropical Cyclone Oswald eroded a significant amount of sand at the base of the original seawall, damaging the foundations and a 200 metre section of concrete.
“Council came forward with a proposal to not only rebuild the seawall but make it better with a longer, stronger stepped structure to improve its resilience to storm surges and wild weather.
“While this project may cost a little more up-front, it will save communities the heartache and expense of repeatedly replacing vulnerable infrastructure.”
Stage one to replace the original seawall is now complete with work underway on the $2.4 million second stage, with $1.9 million from the Betterment Fund, to build a new 250 metre seawall to better protect the foreshore, underground services, drainage, recreation equipment and a public car park.
Moreton Bay Regional Council Mayor Allan Sutherland thanked residents for their patience. “The seawall will have long-term benefits for locals and visitors to this beautiful beach, which is a popular spot for fishing, swimming and walking,” Mr Sutherland said.
“This is an important piece of infrastructure and the extra work we are doing will help improve the resilience of the esplanade.”
Pumicestone MP Lisa France said the project will further enhance the area.
“This section of the Pumicestone Passage is extremely popular with residents, visitors and tourists and we want to do everything we can to protect it,” Mrs France said.
The $80 million Betterment Fund is part of the Newman Government’s push to end Labor’s wasteful approach of rebuilding the same infrastructure to the same standard only to see it damaged again
“The new seawall will help to mitigate the risk of erosion during storm events and deliver safer beach access,” Cr Parsons said.

AUZCON-Stepped Precast Wall
Auzcon Background and Expertise
Our business success comes from our ability to develop valuable partnerships with our clients and the provision of innovative, cost effective and practical solutions to meet their needs. This opportunity for clients is backed up by experienced and knowledgeable staff, providing a large reservoir of accumulated knowledge and expertise that can be utilised for most situations.
Auzcon is committed to quality through continuous improvement through all elements of the job process from concept, to construction, to hand-over.
Auzcon’s expertise has seen the development and patenting of a unique stepped wall design that is easy to build, transport and construct anywhere, anytime. This unique design is suitable for many sites which pose a challenge for many traditionally designed and constructed retaining walls.
Contact Information
Barney Geldenhuys
Mob: 0450117955
Email: barneyg@auzcon.com.au
Email: info@auzcon.com.au
Webpage: Auzcon.com.au
Postal Address: P.O. Box 259, Banyo, QLD 4014, AUSTRALIA