Nanocarbon black based ultra-high-performance seawater sea-sand concrete (UHPSSC) with self-strain sensing capability

The use of seawater sea-sand concrete in marine infrastructure not only offers significant sustainability benefits by minimizing the energy consumption and carbon emissions associated with transportation activities, but also helps mitigate the environmental impact caused by excessive sand mining in riverbeds. The study presented in this paper aims to contribute to this growing area of research by introducing self-strain sensing capability to ultra-high-performance seawater sea-sand concrete (UHPSSC) through the incorporation of cost-effective nanocarbon black (nCB) as a functional filler. Mix designs with different nCB contents were formulated and tested for compressive strength, microstructure and piezoresistive behaviour under different curing conditions. The study concludes that, although the addition of nCB generally decreases the workability and compressive strength of UHPSSC, nCB-UHPSSC with reasonably good properties (i.e., slump spread >160 mm, compressive strength >140 MPa) can be successfully achieved, and its compressive strength can be further increased by one-day dry curing at 105 °C ± 1 °C after 28-day water immersion. The study also shows that the developed nCB-UHPSSC possesses stable and repeatable piezoresistive response with a high gauge factor up to over 160. With its outstanding mechanical and piezoresistive properties, the newly developed nCB-UHPSSC is an economically viable and environmentally friendly option for the construction and monitoring of marine and coastal structures.