Effects of fiber hybridization in advanced cementitious composites durability in humid and aggressive environments

Reactive powder concrete (RPC) is one type of advanced cementitious composite that has been increasinglyused. Its high mechanical strength enables the application of the composite in bolder structures. Consideringits recent history of use, there is a lack of knowledge about this materials durability. Therefore, this paperaimed to evaluate the behavior of hybrid fiber reinforced RPC under accelerated testing, evaluating differenthybrid fiber combinations. Composites contained metallic microfibers and polypropylene fibers in the followingproportions: 100/0%, 75/25%, 50/50%, and 0/0% (metallic/polypropylene). Accelerated tests wereperformed (salt spray, carbonation and acid immersion), as well as 3D microtomography analyses, in order tovisualize the distribution of fibers throughout the matrix. Results indicated high durability under some aggressivewet environments, with no signs of carbonation, nor damage caused by salt spray, and small damagerelated to sulfuric acid attack. In addition, it was possible to observe in the 3D microtomography images thatfibers are well distributed in the matrix volume, and that there is no transition zone in the material due to thereduced volume void.Keywords: Reactive powder concrete; Chemical attack; Durability; Deterioration; Fibers hybridization