Effects of recycled carbon fibers on mechanical and piezoresistive properties and environmental impact in alkali-activated cementitious materials

The development of alkali-activated cementitious materials (AAM) reinforced with recycled carbon fiber (rCF) is of remarkable significance due to its cost-effectiveness compared to virgin carbon fiber, along with the sustainable reuse of solid waste serving as AAM. This study explores the integration of rCF and solid waste Ground Granulated Blast Furnace Slag (GGBS), aiming for cleaner construction practices. A novel approach involving a high-viscosity one-part GGBS slurry ensured homogeneous rCF dispersion, resulting in alkali-activated slag (AAS) mortars with outstanding overall performance at minimal dosage. At a minimum dosage of 0.1 vol%, rCF significantly enhanced flexural strength by 53.42% and reduced drying shrinkage by over 20%. The uniformly dispersed rCF acts as nucleation sites, boosting early compressive strength without compromising long-term performance. Furthermore, the connected rCF network established an exceptionally low percolation threshold (0.125 vol%) and demonstrated promising piezoelectric properties under cyclic loading, illustrating its potential as self-sensing concrete elements. Additionally, life cycle analysis (LCA) underscored the environmental benefits of rCF and GGBS, revealing their potential to remarkably cut carbon emissions (75.36%) and reduce costs (36.5%). These findings provide valuable insights into the development of rCF-reinforced self-sensing mortar with superior mechanical properties, showcasing the substantial potential of rCF in driving the construction industry toward carbon neutrality.