Infrastructure decay is a major problem worldwide. In USA, the American Society of Civil Engineers reported that $1.6 trillion was required to address US infrastructure needs.
Although Australia’s problems are not on the same scale as that of America, there is no reason to be complacent. One Australian port authority engineer has said that he and his colleagues had repaired three of their structures that were around only 20 years old and that they had yet seen not one of their marine structures achieve its design life. This is not an uncommon story.
A survey of experts in 2008 found that America’s infrastructure faces a crisis that even money will do nothing to resolve a lack of vision in setting of priorities and a lack of leadership when it comes to confronting the most difficult challenges.
The Concrete Institute of Australia (CIA) have recognised the problem as having two dimensions: durable structures are essential to a strong economy and durable structures are an important environmental tool.
The Concrete Institute of Australia provide the necessary leadership in the concrete durability arena. To this end, a committee (Z7) has been formed to work on the overall issue of durability. This committee comprises many industry experts involved in developing a strategic plan for durability design and construction in Australia.
The Z7 committee is to conduct workshops around Australia in June 2009 in order to outline the current status of durability design, the problems facing the design and construction sectors and possible options for a way forward. There will be various workshops targeting inputs from asset owners, design engineers, architects, materials suppliers and construction contractors.
One of the major issues to be explored is the development of a performance-based code. While many in the industry believe the necessary reliable performance tests are not yet available, others are already using a diverse range of performance criteria in specifications. This diversity makes it difficult for suppliers and construction contractors and, if performance tests are to be specified, then harmonisation through codes would be useful.
Another major issue to be addressed is the lack of options for concrete choice in the Australian codes. For example, AS 3600, the major code for concrete structures provides only one option for marine structures which is 50MPa concrete with 50mm cover, which is limiting and costly. The Z7 committee believe that, in some cases, the required 40 to 60 year design life may be under-achieved by some margin and another Australian code, AS4997 says that the same design will only provide a 25 year life.
While AS 3600 is the ’leading code’ for concrete structures in Australia, there are various codes that provide guidance for the same environments. Piling, water retaining, marine and bridge structures all have separate design requirements for concrete and these are often in conflict. There is a strong case for having one code that covers all durability aspects in concrete through extracting durability provisions that are listed in all other codes.
Durability is a complex subject. On major projects, advanced deterioration models used by specialists ensure the safest and most economical way of approaching design. Smaller projects however need unsophisticated ’deemed to comply’ rules that, although conservative, can be driven by the general engineering community.
To overthrow the old orthodoxy in concrete durability design, The Concrete Institute of Australia invite stakeholders to attend a June workshop and make it a national important event. The workshop will be held in Adelaide, Perth, Brisbane, Sydney and Melbourne.