Physicomechanical and Hygrothermal Characterization of a Sugarcane Waste / Spent Coffee Grounds Composite for Buildings

Sugar and coffee industries produce considerable amounts of sugarcane bagasse and spent coffee grounds as waste products, these products having very limited value—plant fertilizer for the former and livestock feed or energy source for the latter-. Their valorization potential as construction materials in the built environment is being investigated. In this work, a higher value use of these two agri-wastes is presented through the elaboration and characterization of an environmentally friendly composite material (Starch-bonded sugarcane Bagasse spent Coffee Composite SBCC) for building applications, based on starch-bonded spent coffee grounds reinforced with sugarcane bagasse fibers. The advantages of fiber reinforcement are evaluated by comparison with a previously studied composition solely based on starch and coffee grounds. Samples are characterized in terms of absolute and bulk density, sound absorption coefficient, compressive strength, as well as hygrothermal properties. Fiber incorporation led to a relatively lighter material than the non-reinforced ones, with a bulk density of 321 kg.m−3 while presenting increased mechanical properties, withstanding maximum compression stress of 2.8 MPa, and presenting Young’s modulus of 3.15 MPa. Both thermal conductivity (0.088 W.m−1.K−1) and diffusivity showed a good thermal insulation capacity (0.2 m2.s−1) of the bagasse-reinforced composite. The potential of this new non-structural composite as an acoustic insulator is also assessed, results show that the addition of bagasse did not affect sound absorption compared to the previously studied composites without fibers. In light of the experimental characterization, this new composite would be suitable for use as a non-structural material in building applications. The novelty lies in the association of these two types of co-products (Sugarcane bagasse and Spend Coffee grounds) which can be found on a large scale.