Surface electrical properties of UHPFRC with graphene

The role of graphene inclusion in ultra-high-performance concrete (UHPC) and in ultra-highperformance fiber reinforced concrete (UHPFRC) and the role of steel fibres (used in UHPFRC) have been studied. Surface electrical properties were shown as useful means to deeply investigate the properties of UHPFRC including graphene. Due to the inclusion of fibers a marked increasing of surface conductivity was shown in UHPFRC respect to UHPC. Surface conductivity has been estimated similar to 20 % lower than bulk conductivity in mature UHPFRC. A method for assessing the dispersion grade of graphene in concrete, based on surface electrical measurements and numerical modelling, is presented. In case of mature UHPC, increasing surface conductivity with increasing the graphene content was observed. In case of UHPFRC, graphene within the investigated range of contents (<= 1 % bwoc) was found not to greatly affect surface conductivity. With including graphene, a reduction of microstructural disorder was estimated, whereas the inclusion of fibers was estimated to increase the microstructural disorder.