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

ABSTRACT Reactive powder concrete (RPC) is one type of advanced cementitious composite that has been increasingly used. Its high mechanical strength enables the application of the composite in bolder structures. Considering its recent history of use, there is a lack of knowledge about this materials durability. Therefore, this paper aimed to evaluate the behavior of hybrid fiber reinforced RPC under accelerated testing, evaluating different hybrid fiber combinations. Composites contained metallic microfibers and polypropylene fibers in the following proportions: 100/0%, 75/25%, 50/50%, and 0/0% (metallic/polypropylene). Accelerated tests were performed (salt spray, carbonation and acid immersion), as well as 3D microtomography analyses, in order to visualize the distribution of fibers throughout the matrix. Results indicated high durability under some aggressive wet environments, with no signs of carbonation, nor damage caused by salt spray, and small damage related to sulfuric acid attack. In addition, it was possible to observe in the 3D microtomography images that fibers are well distributed in the matrix volume, and that there is no transition zone in the material due to the reduced volume void.