CONCRETE & CHEMICALS
What does it offer the 360 ° economy?
In an article in Science Direct 2, a succinct summary talks to the benefits of this waste upcycling programme:
• Spent coffee grounds( SCG) can leach organic compounds from the mixture, which routinely hinder the hydration reaction and compressive strength of concrete.
• SCG that is pyrolysed at 350 and 500 ° C- forming biochar- exhibits strong bond formation within the cement matrix.
• As low as a 15 vol % replacement of sand with pyrolysed SCG at 350 ° C provides ~ 30 % improvement in concrete strength.
• The full output of the 75 000 tonnes of waste SCG produced in Australia, could potentially be utilised in structural concrete.
Research team leader Professor Jie Li said that coffee biochar can replace a portion of the sand used to make concrete.“ The ongoing extraction of natural sand around the world – typically taken from river beds and banks – to meet the rapidly growing demands of the construction industry has a big impact on the environment.”
Globally, 50 billion tonnes of natural sand are used in construction projects every year. This is obviously unsustainable – in effect, it mines our resources today while sacrificing the future.
“ There are critical and longlasting challenges in maintaining a sustainable supply of sand due to the finite nature of resources and the environmental impacts of sand mining,” Li said.
“ With a circular-economy approach, we could keep organic waste out of landfill and also better preserve our natural resources like sand.”
... ensuring there’ s a sustainable life cycle for all materials and avoiding things going into landfill...
Co-researcher Dr Mohammad Saberian said the construction industry needs to explore alternative raw materials to ensure its sustainability.“ Our research team has gained extensive experience in developing highly optimised biochars from different organic wastes, including wood biochar, food-waste biochar, agricultural waste biochar, and municipal solid-waste biochar, for concrete applications,” Saberian said.
The RMIT team says it is proceeding to test the long-term durability of coffee-infused concrete, including its resistance to freeze-thaw cycles, water absorption, and abrasion. They’ re also exploring other types of organic waste that could yield similar benefits.
Concrete wall could be made stronger by using biochar.
References
1 https:// www. rmit. edu. au / news / allnews / 2023 / aug / coffee-concrete
2
‘ Transforming spent coffee grounds into a valuable resource for the enhancement of concrete strength’: the Journal of Cleaner Production.( DOI: 10.1016 / j. jclepro. 2023.138205) – free access).
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