Effect of mixing methods on the electrical properties of cementitious composites incorporating different carbon-based materials

Special attributes such as self-sensing ability could be included in conventional concrete-like materials, using carbon-based materials such as carbon nanotubes (CNT), graphene nanoplatelets (GNP) and carbon fibers (CF), which have recently come to the forefront due to their superior mechanical, thermal and electrical properties. However, their non-uniform distribution in cementitious systems stands in the way of taking full advantage of their benefits. To address this issue, an experimental study was undertaken, proposing several mixing methods to achieve uniform distribution. The performance of each method was assessed based on electrical resistivity (ER) and compressive strength measurements. Continuous reductions in ER measurements were observed with time, regardless of the mixing method and carbon-based materials used. Ultrasonication did not appear to be as useful as mechanical mixing with shear effect in terms of ER and compressive strength. Test results revealed that using longer CF (12 mm) in cementitious composites was the best way to tailor matrix properties in terms of electrical conductivity and compressive strength. CF was also easy to mix and has a relatively lower manufacturing cost than other electrically conductive carbon-based materials. (C) 2015 Elsevier Ltd. All rights reserved.