Exfoliated graphene nanoplatelet cement-based nanocomposites as piezoresistive sensors: influence of nanoreinforcement lateral size on monitoring capability

To address the need for innovative multifunctional cement-based materials, this article presents the development of cementitious nano-reinforced composites that exhibit piezoresistive characteristics. It is envisioned that the smart cement-based nanocomposites can be employed as construction materials and at the same time function as stress/strain sensors. To achieve this goal, exfoliated graphene nanoplatelets (xGnPs) were exploited as conductive reinforcement in cement paste. The xGnPs prior to their introduction to the matrix were disentangled using a superplasticizer as dispersant agent and applying ultrasonic energy. The piezoresistive response of the cement-based nanocomposites was assessed by monitoring their electrical resistance change as a function of the applied stress under monotonic compressive as well as flexural tests. The potential of the xGnP cementitious nanocomposites to be used as piezoresistive sensors is demonstrated by the observed linearity between the electrical resistance change values and the respective applied mechanical stress. The effect of the xGnPs lateral size on the monitoring sensitivity of the cement-based nanocomposites was experimentally studied. It is confirmed that the morphology of the nanoplatelets strongly affects the self-sensing performance of the nanocomposites. The xGnPs with the largest lateral size demonstrated an increased change in the electrical resistance proving to be more suitable for improving the monitoring capability of the nanocomposite.