Electrical resistance and self-sensing properties of pressure-sensitive materials with graphite filler in Kuralon fiber concrete

This study aimed to investigate conductivity behavior of concrete containing graphite and its sensitivity to the effects of pressure. Graphite powder was added to concrete to replace partial cement (4 wt.%, 8 wt.%, 12 wt.%, and 16 wt.%) as conductive fillers with a water-to-cementitious ratio of 0.45. Specimens with 0.5 vol.% Kuralon fibers were treated to enhance the performance of self-sensing properties to investigate the influence of graphite and fiber contents on electrical resistivities. The relationship between the axial load and changes in resistivity was determined using cyclic loading tests, indicating the existence and development of internal cracking in concrete. The results indicated that the compressive strength presented a linear decline proportional to the addition of graphite. Specimens with 8% graphite reached the lower bound of self-sensing properties, and with an increase in the amount of graphite, resistivity gradually decreased. In the cyclic loading tests, specimens containing >8% graphite were able to better reflect the relationship between loading and resistivity. Kuralon fibers in concrete had further improvement in resistance and self-sensing properties. In inclusion, the mixture with 8% graphite provided the best self-sensing properties to warn for preventing the effects of cracking, as well as achieved better mechanical properties.