Evaluation of Partial Sand Replacement by Coffee Husks in Concrete Production

Waste production in the industrial sector generates environmental impacts. Thus, it is necessary to search for means to reduce and reuse these residues. Brazil is the largest coffee producer and exporter worldwide, with this being one of the main products in the consumer market, at a production of 30 million sacks per year. Coffee production generates large amounts of by-products, such as husks. Therefore, the reuse of this residue is a good alternative for its disposal. In view of this fact, partial sand substitution by coffee husks in concrete production was evaluated, in order to reduce sand use in concrete manufacturing. For specimen production, traits were formulated by replacing sand by coffee husks at 5%. A 0.5:0.5:1:0.5 (gravel:sand:cement:water) ratio was considered for specimen preparation. To evaluate mechanical compressive strength, assays were performed after 7, 14, 21 and 28 days, using a hydraulic press with 80 MPa capacity. Partial sand substitution by the coffee residue was considered satisfactory, obtaining a compressive strength of ± 20 MPa, higher than the resistance obtained for the concrete produced without sand replacement. Coffee husk use did not compromise material resistance.