Incorporation of coffee grounds into clay brick production

This present study has been conducted to assess the viability of mixing increasing amounts of coffee ground as a solid waste material (1–5 wt-%) with raw clay. Samples have been compressed, dried and fired at 950°C for 24 h to laboratory scale. Using coffee grounds as organic residue has been proven to be effective for pore formation in clay body, increasing its insulating properties yet maintaining acceptable mechanical properties. Small amounts of waste (1–2 wt-%) were found to be effective at forming open cell porosity in clay bricks, which results in worse mechanical and thermal insulating properties. However, bricks with higher amounts of coffee grounds (3–5 wt-%) showed lower density levels and, therefore, higher porosity, which is mainly closed cell porosity, which shows higher insulating capacity and suitable mechanical resistance. Optimal results have been found in bricks with 3 wt-% coffee grounds, showing good mechanical, physical and thermal properties.