Use of Recycled and Virgin Carbon Fibers in Limestone Calcined Clay Cement Composites

The urgent need to reduce the environmental impact of building materials has led to the recent development of low-clinker binders, such as limestone calcined clay cement (LC3). The possibility of using LC3 to produce cement-based composites with high mechanical properties and reduced environmental impact is certainly of great interest. In this study, two LC3 mixtures with different mechanical performances (low and high strength) were investigated. Chopped carbon fibers coming from end-of-life prepreg carbon textiles (rCF), recovered through pyrolysis, and virgin carbon fibers (vCF) were used to reinforce the matrices. Different fiber dosages were investigated, up to 1.5% by volume. Fiber reinforced LC3 composites were characterized through compression and bending tests. The addition of both rCF and vCF results in a decrease in matrix workability, by increasing fiber volume. On the other hand, rCF were able to increase both the compression and bending performances of the cementitious composites, up to 66% and 53%, respectively. Remarkably, no significant differences were found in using rCF instead of vCF.