Concrete and nature seem locked in a one-sided battle as the “concrete jungle” encroaches on the biological jungle. The inspiration for this week’s leaf was a news item about using spent coffee grounds to strengthen concrete – more on that later.

Typical concrete is a composite of gravel or sand and cement, layered or poured into moulds to harden. It has been used for thousands of years, with the Romans adopting it on a massive scale to build bridges, aqueducts and buildings such as the Colosseum in Rome.

Concrete is very strong under compression but has little tensile strength. Thus, in modern building the concrete is poured around steel rods or mesh to make reinforced concrete. However, using steel is not the only way; in countries blessed with bamboo, this strong, natural material is used for multiple purposes, including scaffolding and concrete reinforcement. Bamboo has long lignified fibres that give it great tensile strength (why? See Leaf 5  https://lnkd.in/d3rRNp5R).Bamboo is stronger than an equal weight of steel, making it an excellent alternative for reinforcing concrete.

Production of food and other items from plant produces huge amounts of waste, much of which gets discarded in landfill. Also the botanical extracts manufactured by  @Green Mountain Biotech leave a lot of depleted plant waste. One possible use is for commercialcultivation of fungi for cuisine and medicine; you can expect to hear more on this.

So this brings us to the coffee article (see ref. below). Although the title got me thinking about bamboo-reinforced concrete, the subject was actually very different. Collecting the sand for conventional concrete can cause considerable environmental damage, so the researchers turned to coffee grounds as an alternative, mineralizing them first by heating to very high temperatures to produce a charcoal-like substance called biochar. Using the biochar instead of sand in concrete, resulted in a surprising and impressive 30% increase in compressive strength.

Maybe biochar from otherphytochemically depleted plant waste might work even better!

Further reading

▶Wikipedia (1 September 2023) Concrete, https://en.wikipedia.org/w/index.php?title=Concrete&oldid=1172666549.

▶ Shakil Ahmed (28October, 2021) Bamboo Reinforced Concrete – Strength, Durability, Selection& Water Absorption, https://civilstring.com/bamboo-reinforced-concrete/

▶Darren Orf (AUG 24, 2023)Engineers Just Made Concrete 30% Stronger. The Secret Ingredient? Coffee. Geniushttps://www.popularmechanics.com/science/green-tech/a44892538/engineers-use-coffee-to-make-concrete-stronger/

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