15 Aug 2024

Asbestos in concrete - can it be safely recycled?

7:30 am on 15 August 2024
concrete panels generic

Concrete recycling is now on hold in Taupō and no concrete is currently being accepted for recycling. File photo. Photo: 123RF

Asbestos found in concrete earmarked for recycling in Taupō has raised questions about the viability of concrete recycling across the country.

Taupō District Council said it is testing its stockpiled waste concrete after asbestos was discovered in concrete at its Broadlands Road Landfill.

The council would normally crush the concrete, selling the recycled material on to customers who use it in the construction of roads and driveways.

But after crushed concrete being used on a council project was suspected of containing asbestos, samples were taken from the concrete stockpiles at the landfill. Two of those found a low-level presence of asbestos.

Council chief executive Julie Gardyne said concrete recycling was now on hold and no concrete is currently being accepted for recycling.

About 50 percent of waste comes from the building and demolition industry, 90 percent of which - like concrete - could be reused, recycled, or returned to the supplier.

Construction firm Naylor Love is a strong advocate for waste diversion within the industry. Waikato environmental manager Stephanie Mayer told RNZ in 2023 that the average building site only diverted 17 percent of its waste; in a recent project in Hamilton the company aimed for 80 percent.

Part of this comes from concrete recycling, and its Waikato / Bay of Plenty operations manager Dean McGahey was worried about what the find in Taupō meant for concrete re-use.

"Sadly, given the cost of disposal at landfill, waste concrete may be dump in the environment which could create a bigger public risk," he said.

But he supported the council's approach.

"I think the council are taking a sensible and responsible approach and it is unfortunate that asbestos was common in many building products prior to 2000, and some people may be unaware of this."

Mayer thinks recycling concrete crushing may only be able to continue if all materials were tested first.

"Hopefully they will come up with some form of method for testing [the concrete] before people take it there [to be recycled]," she said.

Asbestos inspector Garry Godfrey said that asbestos used to be found even in products such as baby powder and clothing. He reminded people that asbestos was dangerous only when breathed in as dust.

"It doesn't mean you are going to breath it in today and die tomorrow, because it doesn't work like that. Not everyone gets asbestosis. We've never really worked out what the exposure limit needs to be," Godfrey said.

Several laws regulate asbestos use and removal. WorkSafe advises that construction contractors have a legislated requirement to ensure asbestos is identified and removed before any demolition or renovation work that may disturb the asbestos begins.

"Taupō in itself, I think their processes are very good because they do require testing. Council asks for testing done on most buildings before you are allowed to do any work over there," said Godfrey.

So it was surprising that asbestos products have ended up in the council's concrete recycling programme.

Taupō District Council said it was following expert advice to guide its response to the discovery of asbestos and had been advised it will need to undertake an extensive sampling programme to truly understand the amount of asbestos in the concrete stockpiles.

Of the 12 samples from the landfill stockpiles taken to date, 10 have come back as safe and two samples have come back at the low end of the low level of contamination.

It said it was working directly with customers known to have purchased crushed concrete to have it tested. Where asbestos was present above the safe threshold, council was working with customers to ensure the site was safe and remediated where appropriate.

Gardyne asked anyone who may be concerned about concrete material purchased from Broadlands Road Landfill to contact the council, and reiterated that while asbestos had been discovered, samples had so far been at low levels of contamination.

"We are taking a very cautious approach to managing this situation and while we expect test results to continue to come back as safe or at low levels of contamination, we want to do everything we can to ensure we identify and dispose of any crushed concrete that could potentially pose a risk for the community."

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