Multi-response optimization of fiber-reinforced microcapsule self-healing cementitious composites incorporating recycled PET fine aggregate

Abstract

The unique self-repairing efficacy of microcapsule self-healing cementitious composites (MSHCC) offers significant potential to reduce maintenance costs and extend the service life of infrastructure. To further enhance the mechanical properties of MSHCC, this study integrated fiber-reinforced cementitious composites (FRCC) into MSHCC, forming fiber-reinforced MSHCC (FRMSHCC). An L16 (4⁵) orthogonal array was utilized to optimize the combination of ultrafine ground granulated blast furnace slag (GGBFS), recycled polyethylene terephthalate (PET) particles, microcapsules, water-binder ratio, and fiber type. Range analysis was conducted to assess the influence of each factor on workability and mechanical properties. A life cycle assessment (LCA) was performed to evaluate the environmental impact of microcapsule synthesis, providing a comprehensive analysis of the carbon footprint and economic efficiency of FRMSHCC. The results demonstrated that substituting 10 % of the fine aggregate with PET particles enhanced deformation capacity, whereas a 30 % PET substitution led to a notable decline. Furthermore, the partial replacement of polyethylene (PE) fibers with recycled PET fibers improved compressive properties and reduced material costs. The global warming potential (GWP) of the synthesized microcapsules was quantified at 11.7590 kg·CO₂·eq. The development and multi-response optimization of the composites were carried out based on fluidity, compressive strength, uniaxial tensile strength, uniaxial tensile strain, carbon emissions, and cost, employing the Taguchi-grey relational analysis (GRA) approach. The optimal combinations of FRMSHCC and FRCC were determined through grey relational grade (GRG) rankings and multiple performance indicators. This research advances the field of sustainable construction materials by providing a novel, eco-efficient solution that harmonizes mechanical performance, environmental impact, and cost-effectiveness, thereby contributing to the broader goals of cleaner production and resource conservation in the construction industry.