Mechanical Response and Strain Sensing of Cement Composites Added with Graphene Nanoplatelet Under Tension

Abstract

The piezoresistivity-based strain sensing behavior of cement composites, incorporated with a two-dimensional nano-material was demonstrated under tensile loading. Graphene nanoplatelet (GNP) is electrically conductive nano-particle and thus can be potentially used as an admixture into the cement matrix to lower the electrical resistivity of the composites. Test results indicated that the mechanical performances can be enhanced by the addition of GNP up to 2.4 % due to the nano-filler and micro-crack arrest effects. Beyond this critical content, no further improvement can be noticed partially because of the weak pockets caused by the agglomeration of GNP particles. To depict the relation between mechanical and electrical response of the GNP-specimen, fraction change in resistance (FCR) is introduced to correlate with the tensile strain. It is noticed that FCR continuously increases until failure, with a gentle slope at the first stage (smaller than 100 micro-strains) and a steep slope at the second stage. With more GNP, this slope becomes higher revealing that the GNP-mortar can be used as smart material to sense its own tensile strain. The gage factor can be above 100 when more than 1.2 % GNP was added.