Comparative Life Cycle Assessment of smart self-sensing concrete sensor vs. conventional polyester foil strain gauge sensor: a cradle-to-grave study

Life Cycle Assessment (LCA) is a valuable method for evaluating the potential benefits and impacts of commonly used sensors in structural health monitoring (SHM), particularly regarding the newly proposed smart self-sensing concrete sensor (SSCS). Each year, various strain sensors are used to monitor bridge conditions, raising concerns about which sensors are more environmentally friendly. This study compares the environmental impacts of SSCS and conventional polyester foil strain gauge (SG) sensor throughout the cradle to gate and cradle to grave processes, with a particular focus on the sensors themselves. To promote a low-carbon monitoring approach, it is essential to conduct LCA for strain sensors, which are critical to SHM systems, especially in bridges. This comparative analysis revealed that SGs exhibit substantially higher environmental impacts up to 95 % greater across key categories (RI, TEcoTOX, GWP, NRE, and ME) in cradle to gate mainly due to copper use, metal refining, and limited recyclability, whereas SSCSs demonstrate up to 99 % lower impacts when recycling is included in cradle to grave. Using the IMPACT 2002 + single-score method in cradle to gate, copper in SG contributes the highest impact (∼9.4 Pt), nearly 82 % greater than the carbon black in SSCS (∼1.6 Pt), while the inclusion of recycling reduces SSCS impacts drastically to below 0.2 Pt across all categories. Sensitivity analysis on transportation distance shows negligible influence on both sensors, confirming manufacturing as the dominant source of environmental burden. Finally, replacing Portland cement in SSCSs with Ground Granulated Blast Furnace Slag (GGBS) or Portland Pozzolana Cement (PPC) decrease resources environmental impact by 29 % and 30 % compared with SSCS, respectively.