Limestone calcined clay cementitious (LC³) paving flags with textile waste fibers and fine recycled aggregates: Mechanical, durability and multi-criteria sustainability analysis

The demand for a sustainable built environment is steering construction materials research towards finding effective methods to reduce carbon emissions in concrete production. In this context, this study explores a triple-strategy approach oriented to increase the decarbonization potential of cementitious flags: (1) limiting Portland cement to 51 % by incorporating limestone-calcined clay; (2) reinforcing the matrix with nonwoven textile waste fabrics; and (3) replacing natural aggregates with fine recycled aggregates from construction waste. Mechanical (flexural and uniaxial tensile strengths), weathering resistance (accelerated wet-dry cycles, freeze-thaw cycles, and water absorption), and serviceability parameters (thermal/acoustic insulations, abrasion, and post-fire residual resistance) of composite paving flags were characterized in laboratory conditions. Further, microstructural analysis and digital image correlation technique were implemented. The 30 mm-thick composite intended for paving flag reached the maximum flexural and tensile strengths of 8.9 and 2.1 MPa, respectively. Deflection- and strain-hardening behavior was observed due to the synergistic interactions between the matrix and fiber. Despite relatively high water absorption ≥10 %), the composite could satisfy the minimum requirements per standard for freeze-thaw and abrasion resistance. Finally, a sustainability performance analysis using a multi-criteria decision-making method—considering both environmental and socio-technical aspects—confirmed the composite’s viability from technical and sustainability standpoints, achieving satisfaction values of ≥ 0.7 on a 1.0 scale.