A fault at an Auckland, New Zealand, batch plant has resulted in up to 70 projects receiving substandard concrete including the NZ$1.4bn (£660M) Waterview highway project.
The Waterview Connection project is one of the most important infrastructure developments ever to take place in New Zealand and will complete a motorway ring route around the city.
It involves construction of 4.8km of six-lane highway, with half of it underground – making it the largest road tunnel in Australasia.
The NZ Transport Agency confirmed that its Waterview Connection project is one of the construction projects in Auckland that received some faulty batches of concrete from its supplier in late April.
But in a statement, Transport Agency Highways Manager Brett Gliddon stressed the integrity of the project would not be compromised.
The Well-Connected Alliance, which is delivering the Waterview Connection for the Transport Agency, is working with supplier Firth Concrete to identify areas affected and carry out the necessary remedial works.
“The quality control systems put in place by the Well-Connected Alliance helped identity the problem,” said Gliddon.
On site investigations confirmed an elevated section of the road project, on the Great North Road Interchange, will have to be repaired. Some retaining walls, footpaths and crash barriers have also been affected. Gliddon added the delivery of the faulty concrete will not impact on the project’s overall programme of works, nor on its planned opening in early 2017.
The problem is believed to have stemmed from a failure of weighing apparatus at the plant, which resulted in insufficient cement being added to the mix. The plant is operated by Firth Concrete, a company owned by Fletcher Building, one of New Zealand’s biggest listed companies.
Firth said it first spotted the problem at the end of April. It said it immediately stopped production at one of its Auckland production plants after the company’s quality control testing programme found some concrete from that site had not met product specifications.
“Customers were informed on the day the issue was discovered and Firth is liaising with each customer to assess the need for remedial action required on a case by case basis,” said the firm in a statement. “Each site has been visited by a Firth representative to test the concrete and assess the need for remedial action. In approximately half of the cases no action will be needed and the concrete will remain in place.”
Firth General Manager Andrew Moss said its investigations indicate faulty measuring equipment at the site, leading to a low cement content in the mixes, and as such the issue is isolated to that site. The plant has since reopened.
New Zealand’s Cement and Concrete Association (CCANZ) chief executive Rob Gaimster said the discovery of the problem showed that New Zealand was “fortunate to have robust quality assurance standards for ready-mix concrete”.
“There was a malfunction at the Firth plant and that was picked up as part of the supplier’s rigorous quality assurance procedures and they alerted their customers,” he said. “This was a weigh scale issue.”
Firth has been producing concrete for 90 years and has more than 6,000 major customers. The company produces more than 1M.m3 of concrete at 70 production plants nationwide for a wide range of residential and commercial purposes.
The cost of the error and remedial works has yet to be assessed.