Experimental investigation of output performance and fatigue degradation of road piezoelectric energy harvesters embedded in SMA pavements

Road piezoelectric energy harvesting has advanced through transducer optimisation, yet the role of asphalt-mixture design in pavement–harvester coupling remains poorly understood. We compared asphalt–piezoelectric pavement specimens incorporating stone mastic asphalt (SMA) mixtures (SMA-10, SMA-13 and SMA-20) with AC-10 specimens. Embedded lead-free harvesters were tested under cyclic loads of 2–10 kN at 2–10 Hz to quantify electrical output and voltage degradation. Output increased among SMA mixtures with increasing nominal maximum aggregate size, reflecting the effects of aggregate structure, surface-layer stiffness, and mixture composition on pavement–harvester load transfer. SMA-20 achieved a maximum root-mean-square open-circuit voltage of 91.23 V and peak output power of 627.16 mW. After 10 days of intermittent loading, corresponding to approximately 4.32 × 106 laboratory loading cycles, its output voltage decreased by 19.41%. Full-scale field tests reproduced this output ranking under vehicle loading. These results highlight the importance of asphalt-mixture design for energy-harvesting pavement systems.