The Facts about Coffee in Concrete
Researchers have discovered a method to enhance the strength of concrete by incorporating used coffee grounds. It increases the material strength by 30% and offers a more sustainable alternative to the mined sand on which the concrete industry depends and is a cost-effective solution to strengthen concrete structures.
Heating coffee grounds to temperatures of 350 °C and 500 °C is crucial to ensure their suitability for utilisation in concrete. These high temperatures serve several important purposes in maximizing the potential benefits of coffee grounds in concrete.
Coffee grounds are a significant waste product in Australia, with an astonishing 75,000 tons being generated annually by shops and households alone. Most of this ends up in landfills and is a waste of this high carbon resource.
Coffee grounds can be utilized to both prevent the disposal of waste in landfills and enhance the strength of concrete. Additionally, this innovative approach has the potential to mitigate the environmental deterioration caused by the extraction of natural sand, which serves as a fine particle aggregate in concrete production.
The Process of Adding Coffee to Concrete
Traditionally, concrete is strengthened by adding supplementary cementitious materials including fly ash or silica fume.
However, these materials are often expensive and have negative environmental impacts. By utilizing waste coffee grounds, a team of researchers at RMIT University in Australia, have found an eco-friendly alternative that not only boosts concrete strength but also reduces landfill waste.
The process involves collecting used coffee grounds from local cafes and processing them to remove oils and other impurities. These refined coffee grounds are then mixed into the concrete mixture during production.
The coffee particles act as a filler, increasing the density of the concrete and reducing the formation of microcracks. This results in a significant improvement in the overall strength and durability of the material.
The high silica content present in coffee grounds reacts with the calcium hydroxide in the concrete, forming additional calcium silicate hydrate. This reaction contributes to the increased strength and enhances the binding properties of the concrete.
Can I put coffee grounds straight into my concrete to make it stronger
To incorporate coffee grounds into concrete, they should be properly dried and ground to a fine powder. The coffee grounds can then be added gradually to the concrete mixture during the mixing process. It is crucial to ensure uniform distribution of the coffee grounds throughout the mixture to achieve desired results.
The experiment at RMIT involved subjecting sand to temperatures of 350 and 500 degrees Celsius and subsequently incorporating the sand at varying proportions (5%, 10%, 15%, and 20% by volume) in standard concrete mixtures.
Researchers at RMIT discovered that 350 degrees is the perfect temperature, producing a “29.3 percent enhancement in the compressive strength of the composite concrete blended with coffee biochar”.
How do coffee grounds in concrete make the concrete stronger?
Coffee grounds in concrete can contribute to its strength due to their unique chemical composition and physical properties. When coffee grounds are added to the concrete mixture, they act as a supplementary cementitious material and enhance the overall performance of the concrete.
Coffee grounds contain a significant amount of silica, which is a key component of cement. This silica reacts with calcium hydroxide present in the concrete to form calcium silicate hydrate, a gel-like substance that strengthens the material. Coffee grounds also possess a porous structure, promoting better adhesion between the cement paste and aggregates, leading to improved bonding and increased strength.
The organic compounds found in coffee grounds, such as lignin and cellulose, can act as natural admixtures. These compounds help to reduce water demand during the hydration process, thus enhancing the density and durability of the concrete. The presence of coffee grounds also aids in reducing the overall porosity of the material, making it less permeable to water and reducing the potential for cracking and deterioration.
Every year, the construction industry heavily relies on extracting an astounding 55 billion tons of natural sand for the production of concrete. This is because the rough exterior of sand particles offers a significantly larger surface area, facilitating a more effective binding process between water and cement. By utilizing SCG, we can simultaneously reduce sand consumption, alleviate environmental damage caused by sand mining, manage coffee waste sustainably, and enhance the properties of various construction materials. This approach showcases the potential for creative thinking and sustainable practices in addressing environmental challenges.
Used coffee grounds have a multitude of applications beyond being used in concrete. One common use is as a natural exfoliant in skincare products. The coarse texture of coffee grounds helps to remove dead skin cells, leaving the skin feeling smooth and rejuvenated. Moreover, the caffeine present in coffee grounds can help reduce puffiness and tighten the skin, making it a popular ingredient in eye creams and face masks.
Coffee grounds can be utilised in gardening. They are rich in nitrogen and other nutrients, making them an excellent fertilizer for plants. The grounds can be sprinkled directly onto the soil or added to compost to enhance its nutrient content. Coffee grounds also act as a natural deterrent for pests like slugs and snails, keeping them away from vulnerable plants.
In terms of household uses, coffee grounds can be employed as a natural odour absorber. Placing a bowl of coffee grounds in the refrigerator or freezer helps eliminate unwanted smells. It can be used to remove stubborn odours from hands after handling strong-smelling foods like garlic or fish.
Another interesting application is using coffee grounds to dye fabrics, paper and wood. When brewed coffee or wet coffee grounds are applied to certain materials, they can create unique brown or sepia tones, adding an artistic touch to various crafts and projects.
