Sustainable and smart: Piezoresistive cement mortar with conductive polyaniline-modified recycled plastics

Direct replacement of aggregates with recycled plastics generally weakens the strength of the cement composite and decreases its electrical conductivity. This study presents a sustainable, cost-effective alternative by coating waste plastics with polyaniline, a conductive polymer, using a rapid 1-min microwave process that forms a stable coating with minimal polymer use. The coated plastics mitigate strength loss typically seen with plastic aggregates, while improving pore structure and reducing water sorptivity by nearly one-third. Electrical conductivity was enhanced, with resistivity reduced by one order of magnitude compared to conventional mortar, and a notable fractional change in resistivity (FCR) of nearly 12 % under compressive loading. The polyaniline coating decreased the porosity of the interfacial transition zone (ITZ) by 35 % and contributed negligible CO₂ emissions during implementation. The findings offer a promising step toward eco-friendly, smart construction materials that convert waste into functional value.