Effects of Cashew and Coffee Ash as Partial Replacement for Cement on the Mechanical Properties of Concrete

Vietnam is one of the biggest producers and exporters on the world of cashew nuts and coffee beans. Cashew nut shells and coffee husks generated during their production can be used as a burning material to maintain oven heat. However, if the waste products, cashew and coffee ash, resulting from this combustion are not recycled, they can contribute to air and environmental pollution. Additionally, the production of cement, an essential raw material for concrete, emits a significant amount of carbon dioxide into the atmosphere. To address these issues, this research proposes the use of a mixture of cashew and coffee ash as a partial substitute for binder content (cement) in concrete production. Five replacement ratios (0, 5, 10, 15, and 20%) and two concrete mixtures (B15 and B25) were investigated. The compressive strength of all the concretes was evaluated through compression tests on cube specimens. Based on the test results, the compressive strength of concrete was found to decrease as the replacement ratio of cashew and coffee ash increased. In contrast to concrete B15, concrete B25 exhibited a negligible reduction in compressive strength when the replacement ratio of cashew and coffee ash reached 15%.