Performance-based functional units for carbon assessment of geogrid-reinforced pavements

This study introduces performance-based functional units (FUs) for cradle-to-gate life cycle assessment (LCA) of geogrid-reinforced pavements, addressing limitations of conventional material-based FUs that overlook structural performance. Laboratory results from cyclic plate load testing were used to demonstrate the approach. Global warming potential (GWP) and embodied energy (EE) were normalised by rutting resistance (FU1) and load cycle capacity (FU2), providing measures of carbon and energy efficiency linked directly to mechanical behaviour. Although reinforced sections exhibited higher absolute cradle-to-gate GWP and EE due to the additional geogrid layer, their performance-normalised values indicated substantially greater efficiency. The best-performing section achieved a 13·42-fold increase in cycles per unit impact relative to the unreinforced case, increasing from 82·71 to 1110·07 cycles per unit impact. Monte Carlo simulations incorporated layer-density variability, and variance decomposition confirmed that hot mixed asphalt density dominates uncertainty due to higher emission and energy factors and, in some sections, greater coefficients of variation. These findings highlight the importance of accurate measurement of material properties in LCA. The proposed framework provides a transparent, experimentally grounded basis for integrating structural performance into pavement LCAs.