Matrix-centric design of alkali-activated slag mortars through binder chemistry and rheology control for more practical and sustainable piezoelectric cementitious composites

Achieving practical, concrete-compatible piezoelectric cementitious composites remains challenging because many reported systems rely on very high ceramic contents, costly conductive additives, or processing routes that omit aggregates or require laboratory-specific steps. In this study, alkali-activated slag (AAS) mortars were developed through a matrix-centric design approach to obtain more practical and sustainable piezoelectric cementitious composites. GGBFS content, Na 2 O dosage, and water-to-binder ratio were systematically varied to tailor binder-system chemistry and enhance ionic conductivity, while fresh-state rheology was adjusted to enable uniform PZT dispersion and effective poling at practical contents. Bulk electrical resistivity served as the primary design metric, while fresh-state tests were used to assess flowability and rheological stability. Compared with the matched Portland-cement reference, the AAS reference mixture showed lower bulk electrical resistivity, decreasing from 1.79 to 0.24 kΩ cm at 7 days and from 7.19 to 5.74 kΩ cm at 100 days. With further adjustment of binder content and equivalent Na 2 O dosage, this value was reduced to 2.54 kΩ cm at 100 days while preserving favorable rheology. This enabled production of a castable composite containing ∼28 vol% PZT without solvent processing or conductive additives. Moisture conditioning before poling was critical, producing post-poling d 33 values of 30-42 pC/N, with 23-32 pC/N retained after two weeks, while microstructural observations confirmed chemically stable, well-adhered PZT particles. These results show that matrix design and moisture control, rather than additive-driven conductivity enhancement, can provide a feasible and cost-conscious route to more practical and sustainable piezoelectric cementitious composites. • AAS matrix chemistry enabled practical, sustainable PZT cementitious composites. • Binder chemistry and rheology jointly governed PZT dispersion and poling. • A castable ∼28 vol% PZT composite was produced without solvent processing. • Aggregate-containing piezocomposites were produced without conductive additives.