Analysis of Stiffness and Moisture Resistance of Asphalt Mixtures with Biomaterials: A Case Study in Brazil

With the increasing popularity of the low-carbon and environmental protection concept, bio-based materials have gained attention from researchers. This study assessed the effects of adding three distinct biomaterials (carnauba and beeswax waxes, sunflower and canola vegetable oils, and pinus and eucalyptus lignins) on the mechanical performance, addressing stiffness and moisture susceptibility in dense asphalt mixtures. The additives were incorporated at a ratio of 3% relative to the weight of the asphalt binder, which had a 50/70 penetration, and were used in mixture production. Performance evaluation included tests for tensile strength by diametral compression, resilient modulus, and damage induced by moisture. The results indicated that asphalt mixtures with lignin show tensile strength and resilient modulus comparable to wax-containing mixtures. All formulations, except those with beeswax, proved suitable for field application, with the latter recommended for use in low rainfall regions, accompanied by an adhesion enhancer. On the other hand, mixtures with vegetable oil are suitable for low-traffic roads, given their high flexibility and low resilient modulus. The study highlighted distinct behaviors of these biomaterials regarding stiffness and moisture damage, emphasizing lignin as ideal for roads subjected to higher stresses and wax/vegetable oil for mixtures with high stiffness, such as those composed of recycled material.