[+] Concrete Challenge for Net Zero Future

Australia’s built environment heavily depends on concrete, the world’s second-most consumed material. But it’s weighing on the environment and the federal government has cement companies squarely in its sights for emissions targets as some of the country’s top 215 polluters. Groups including Boral, Adbri and Cement Australia made the list, with $1 billion set aside to support the decarbonisation of steel, cement and aluminium industries—while cement makers are also able to buy carbon offsets. The challenge will be that it adds to costs downstream in an already challenged construction industry. But behind the scenes concrete is forging a new future as key industry players work to make it more environmentally friendly, and increasingly developers are picking up the products. At the heart of the concrete conundrum is cement, the main ingredient binding sand and gravel to give it its undeniable strength. As the world’s No.1 building material, a whopping 4 billion tonnes of cement are produced a year. Overhaul coming But the green glitch is that cement is responsible for about 7 per cent of global carbon dioxide (CO2) emissions, according to McKinsey research—a significant slab of the 40 per cent of emissions attributed to the built environment each year. As a result, the way cement and concrete are produced—and used—must be overhauled if the world’s collective construction sectors are to meet the net zero by 2050 goals set out in the Paris Agreement on climate change. Companies are now working with carbon neutral concrete, which is produced using processes that dramatically minimise (or even eliminate) the amount of CO2 released during its fabrication. Michael Kemp, chief executive of Earth Friendly Concrete, says that from the moment the federal Labor government started talking about a carbon tax around 2007, his team got to work. “We set out to make concrete without cement. We thought, ‘Let’s remove the problem altogether’. Although the tax didn’t get up, we started playing in the lab and quickly realised there were a number of applications where concrete without cement—we call it geopolymer concrete—was actually better than ordinary concrete.” ▲ Concrete is the world’s top building material and makers are innovating to lower its carbon footprint. Cement-free solution Earth Friendly Concrete, an initiative of Australian construction materials company Wagners, has so far produced a number of high-profile projects using the cement-free solution, including the turning node and apron for the runway at Wellcamp Airport in Toowoomba and Pinkenba Wharf in Brisbane as well as getting a nod from the Australian Museum recognising their product as one of Australia’s top climate solution technologies. “We save 220kg of CO2 for every cubic metre as an average, which out of all the low carbon concrete that’s happening in the world, it’s the biggest gap by a good margin and that’s because we’ve taken the cement completely out,” Kemp says. Dr Ali Nezhad, head of sustainability and innovation at Boral says today’s concrete producers have a responsibility to create change in a sector with such a hefty burden. “While concrete by itself is not a carbon-intensive material compared to many other materials such as steel, the large quantity of concrete used globally results in a high carbon footprint for our industry,” he says. “Lower carbon or carbon neutral concrete looks at the entire life cycle of the product, where emissions reductions can be achieved cumulatively throughout the material’s full life cycle, not just through a single change. This includes via component or source materials selection, manufacturing, transportation, and construction processes; and post-construction maintenance, repair, and disposal or reuse.” ▲ Concrete is a mainstay of the construction industry, prized for its strength and durability. Gaining momentum Dr Nezhad says Boral has been ambitious when it comes to its emissions reduction targets. “Demand for our lower carbon concrete is gaining momentum and it’s our ambition to make that standard at our batching plants. Our customers and the market has changed, they’re looking for more sustainable solutions and we can see that through the growing demand for our Envisia lower carbon concrete products,” he says. So far the path to carbon-neutral concrete is being paved with alternative lower carbon footprint materials used in the production process such as fly ash or slag to replace a portion of or all the cement used in the concrete mix. As new methods take shape, price does come into play, but Kemp says the competitiveness of cement-free concrete will continue to strengthen. “We’ve produced about 70,000 cubic metres, and on most of those projects we’re selling concrete at a premium of about 30 per cent. Considering that across Australia 70,000 cubic metres would probably be poured before ‘smoko’, we’ve got a lot of opportunity to scale up, greatly accelerate research and to build the business,” he says, adding that the higher cost can already be offset by using less concrete given the proven strength of the newer product. Another avenue to carbon neutral concrete, also being trialed globally, is known as carbon capture and storage (or CCS) where the CO2 is captured at the point of emission, then transported and permanently stored in underground geological formations. “We think it’s admirable but it’s going to need a lot of capital, a lot of investment and a long time to make things happen. I applaud the efforts going into it, but our approach has been, ‘Let’s not make the mess and then have to clean it up’. And the cost of putting carbon capture and storage on to the bill is going to make cement more expensive. Not making the cement in the first place will end up being the cheapest way to do it,” Kemp says. ▲ Green shoots are appearing in the concrete industry as more eco-friendly solutions come to market. Exciting advances An alternative to cement-free concrete is treating traditional concrete in a manner that effectively “neutralises” it. Nezhad says there are exciting advances being made in the field of recarbonation, a process where concrete actually absorbs carbon through its lifecycle. “It’s a slow process that occurs in concrete where calcium hydroxide within the cement reacts with carbon dioxide and forms calcium carbonate. “The concrete stores the carbon dioxide permanently. “The process of recarbonation has been acknowledged and confirmed by the Sixth Assessment Report of the United Nation’s Intergovernmental Panel on Climate Change and it’s important that it’s recognised here in Australia given its potential impact on net emissions,” he says. 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[+] Concrete Challenge for Net Zero Future

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