Durability Issues of Older Structures exposed to Salt Spray

Hi Everyone

I am reaching out to all my Linkedin associates (and others) for your assistance on the topic of durability testing of reinforced concrete mid to high rise structures on or near the coast in Australia (or NZ).

I have a friend who owns a unit in a high-rise tower on Sydney Harbour. Five years ago, he asked if his tower was safe, after I had told him about a second storey balcony falling off from a 3 storey building in Manly NSW back in 2002. The residential tower he lives in at the time was 45 years old.?I told him about carbonation and chloride testing that is normally done on bridges and older structures especially near a coastal environment.

He advised his body corporate of that balcony collapse in Manly and the potential durability and corrosion issues that could impact their structure if they did not get an assessment done, but the Committee decided it was not necessary to investigate or pursue the matter any further (basically swept the issue under the carpet).

When the Champlain Tower collapsed recently in Miami, he and I discussed this durability situation again, especially now that his structural building was over 50 years old and exposed to sea water, wind and salt spray.

He again forwarded a proposal to the building Body Corporate (with my assistance), and again they dismissed it saying that from their research no other buildings along the Sydney shoreline are having these types of tests carried out. In particular they were of the belief that because their building was “in the harbour” as opposed to on the coastline, the durability issue would not be as great.

Their reply to the need for durability testing to be carried out was the following:

“The committee has made its own enquiries which did not reveal any assessments of strata buildings of this kind.?To enable the committee to give further consideration to this issue, could you please provide the actual numbers of strata buildings of similar age in Greater Sydney, that are not on the coastline/beaches, of which you are aware where such assessments have been carried out and with regard to at least four of them provide the following information: (a) who conducted the assessment (b) the outcome (c) the approximate cost of the assessment.”

When I saw the wording “not coastline/beaches” I immediately knew that they had no idea about the requirements of AS3600 #4.3 Clause 3(c) (Note 5) which states that “COASTAL ZONE includes locations within 1 km of the shoreline of large expanses of salt water”. This obviously means that whether a building is on the coast or inside the harbour, the durability issue with regards to salt ingress is the same.

I therefore ask all of you (if you would not mind) to send me information regarding any structures that you know of, where durability testing has been, or is being carried out, on building structures along ANY saltwater ways in your city (not just Sydney harbour or the NSW coastline). If you have information on the “outcome and costs of those assessments” that would be even better for our case.

I do not want to see any structures in Australia suffer the same fate as happened in Miami because of the reluctant body corporate committees who take it upon themselves to make such ill-informed, non-technical assessments, to “not” carry out durability testing purely based what they believe is the status quo in the construction industry at present, or based upon the “costs” associated with supposed non-warranted testing of reinforced concrete structures. Structures built in the 1970’s used 20 MPa and 25 MPa as their standard grades of concrete, however we know today that these grades do not satisfy the durability requirements of the Code and if those same structures were built today the concrete grades required would be 32 MPa to 40 MPa (minimum).

I can assure you that since Champlain Towers incident in Florida (Miami), authorities in the USA are scrutinizing many more ‘older’ structures (and balconies) built along water ways than in the past. We don’t want to suffer the fate of a Champlain (or Grenfell with the aluminium fire cladding issues that many professionals were aware of, including myself, before the incident happened in the UK in 2017) just because the majority of people would not listen to the minority of engineers and building professionals warning them of failures and potential death if something was not done to address those issues earlier.

Please send your Durability Case Study Reports to me at [email protected] .