Compressive strength, acoustic and aging piezoelectric properties of 1–3 and 2–2 connectivity lead-free BNBT piezoelectric ceramic/Portland cement composites for structural health monitoring applications

• 2-2 composite shows higher compressive strength, d 33 , FoM, K than 1-3 composite. • 1-3 composite shows higher g 33 than 2-2 composite. • 40 vol.% BNBT shows structural compatibility and highest g 33 for SHM sensors. • At ages 1-30 days, the composites showed higher g 33 than BNBT. 1-3 and 2-2 connectivity lead-free 0.94Bi 0.5 Na 0.5 TiO 3 -0.06BaTiO 3 (BNBT) ceramic/Portland cement composites were designed and fabricated for use as sensors in structural health monitoring applications. This study investigates the effects of BNBT content and composite connectivity on compressive strength, acoustic, and aging piezoelectric properties, with the aim of optimizing composite performance. Composites containing 40-70 vol.% BNBT were prepared using cut - and - fill technique. The highest measured values of d 33 and g 33 were 115 pC/N and 26.07 × 10⁻ 3 Vm/N, respectively. The results demonstrate that increasing BNBT content and employing 2 - 2 connectivity enhance the compressive strength of the composites, with 2 - 2 composites showing superior performance compared to 1 - 3 composites. All composites exhibited higher compressive strength than concrete. The composite with ∼40 vol.% BNBT showed good compatibility with concrete. Between 1 and 60 days of aging, the g 33 values of composites remained higher than those of standalone BNBT ceramic, highlighting a notable advantage of composite design.