We know that coffee has varied and positive properties. But build buildings? That’s something new. A concrete mix was developed that incorporates biochar made from coffee grounds. The innovation reduces cement consumption by around 10%, while improving product quality. Concrete made with coffee is the most recent advantage of this bean.
Coffee is one of the most popular drinks in the world. It results in approximately 14 million tons of wet coffee waste per year, taking into account the seven million tons of coffee produced annually worldwide.
Biochar
The researchers explained that organic materials, such as coffee grounds, cannot be added directly to concrete. This is because they release chemicals that weaken the building material. To prevent this, the team heated the coffee grounds to 400°C. In this way they were able to eliminate the oxygen and then ground the grounds. Thus they were able to obtain a porous carbon rich in carbon known as biochar.
They found that this additive not only reduced the use of cement. It also improved the properties of the resulting concrete. To achieve optimal concrete characteristics, the biochar content must represent around 4% of the weight of the mixture. «The resulting concrete has excellent physical and mechanical properties and a high quality structure. “It can be used in residential, commercial and social construction projects.” This is clarified by the head of the construction department of the Don State Technical University (Russia). He is also one of the authors of the study: Sergei Stélmaj.
He adds that when used in rational doses (no more than 8%), the biochar from coffee grounds acts as a mineral filler. Its particles densify the concrete structure. They make it more uniform and improve the resistance of the material.
Huge resistance
«Microscopic images show that the overall distribution of biochar in the concrete is uniform, without areas of weakening or excessive reinforcement. In our opinion, this research is universal. It could find applications in other countries, especially those that are large coffee exporters, such as Brazil, Vietnam, Colombia and Indonesia,” said Stélmaj.
Future research will focus on studying the durability characteristics of concrete made with coffee and additives. Scientists plan to conduct experiments on frost resistance, water impermeability and resistance to alternating cycles of wetting and drying. They also intend to apply these new compositions in the production of concrete. The results were published in the journal recycling.
