In a groundbreaking study published in the journal *Frontiers in Built Environment*, researchers have demonstrated a novel way to repurpose spent coffee grounds (SCG) into a valuable construction material, potentially revolutionizing the brick manufacturing industry. Led by Amani Abdallah Hepautwa from the Department of Materials and Energy Sciences and Engineering at the Nelson Mandela African Institution of Science and Technology in Arusha, Tanzania, the research explores the integration of coffee ash biochar (CAB) into burnt red soil bricks, offering a sustainable solution to waste management and construction material innovation.
The study investigates the mechanical, chemical, and microstructural performance of bricks incorporating CAB, which is produced by pyrolyzing spent coffee grounds at varying temperatures. “We aimed to address the environmental challenges posed by spent coffee grounds while enhancing the properties of traditional red soil bricks,” Hepautwa explained. The findings reveal that incorporating CAB into red soil bricks can significantly improve their mechanical properties and durability.
The research team conducted comprehensive comparisons using coffee ash pyrolyzed at temperatures of 300 °C, 350 °C, and 500 °C, substituting red soil at replacement levels of 5%, 10%, 15%, and 20%. The results indicated that the mechanical properties of the bricks decreased with increasing coffee ash content. However, under optimal water-cement ratios, the compressive strength of red soil bricks containing 5% SCG increased by 49.7% compared to the control when pyrolyzed at 350 °C. For bricks with 10% SCG, compressive strength improved by 53.5%, flexural strength by 66.1%, and splitting tensile strength by 38.4% when pyrolyzed at 300 °C.
Moreover, the study found significant reductions in water, chloride, and sulfur penetration by 41.5%, 44.4%, and 34.3%, respectively, indicating improved durability and resistance to environmental factors. “This approach not only addresses the disposal challenges of spent coffee grounds but also benefits the economy and the environment,” Hepautwa noted.
The research employed advanced analytical techniques such as Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Differential Scanning Calorimetry (DSC) to evaluate the microstructural integrity and bonding mechanisms within the composite materials. The findings suggest that SCG pyrolyzed at 300 °C and 350 °C, particularly at a 10% and 5% replacement level, delivers the best mechanical and chemical performance.
This innovative approach highlights the environmental benefits of using spent coffee grounds in red soil brick manufacturing, reducing landfill waste and carbon emissions. “Future work will focus on durability and scalability for industrial applications,” Hepautwa added, emphasizing the potential for broader adoption in the construction industry.
The study, published in *Frontiers in Built Environment* (which translates to *Frontiers in the Built Environment* in English), demonstrates the feasibility of incorporating SCG into burnt red soil bricks and examines the impact of SCG on their performance. This research could shape future developments in sustainable construction, offering a viable solution for waste management and resource efficiency. As the construction industry continues to seek eco-friendly and cost-effective materials, the integration of coffee ash biochar into brick manufacturing presents a promising avenue for innovation and sustainability.