Flexural behavior of sandwich panels combining curauá fiber-reinforced composite layers and autoclaved aerated concrete core

•Sandwich panels with natural fiber reinforced composite skins and AAC core are a sustainable alternative to construction materials;•Sandwich panels’ bonding between FRC and AAC demonstrated a predominant composite failure and a satisfactory adhesion in the short and long terms;•The unidirectional curauá fiber reinforcement is capable of bridging the cracks and increasing the energy absorption capacity of the composite skin layers;•Subjected to cyclic loading, the panels exhibited a composite response with gradual energy loss and adequate ductility. The mechanical response of sandwich panels with two layers of curauá fiber cement composites and a core layer of autoclaved aerated concrete (AAC) was investigated. Each layer consisted of long unidirectional curauá fibers and a cementitious matrix. For durability purposes, 50% of the Portland cement was replaced with pozzolanic materials to reduce the content of calcium hydroxide in the matrix. The performance of sandwich panels with 350 mm × 60 mm × 90 mm (length × width × thickness) was evaluated through monotonic and cyclic four-point bending tests to obtain the load–deflection response, flexural strength, and toughness. Monotonic bending tests were performed on each component of the panels – i.e., composites and AAC blocks. Pull-off tests were performed to evaluate the adhesion between the skin layers and the core, while optical and scanning electron microscopes were used to observe the interface's topography. The results revealed the externally bonded layers' efficiency, which provided a higher deflection capacity to the material and increased its flexural strength. The AAC blocks revealed a more ductile response when assisted by the composite layers in the sandwich structure. Under cyclic bending test conditions, the sandwich panels exhibited a satisfactory post-peak ductility so that the energy was not abruptly lost but gradually released throughout its deflection-softening behavior.