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As a material for road deicing and snow removal, electrically conductive concrete (ECON) can convert electrical energy into thermal energy to automatically melt ice and snow, avoiding manual and mechanical operations. However, to achieve ideal electrical conductivity, the content of single-doped conductive fillers in ECON needs to be high, which leads to poor workability of ECON and agglomeration of conductive fillers. Combing conductive fillers with different scales helps reduce the content of single-doped conductive fillers in ECON. This study prepared composite conductive concrete using multilayer reduced graphene oxide (RGO), carbon fiber, and steel fiber as conductive fillers. The effect of multilayer RGO on composite conductive concrete's compressive strength, flexural strength, and electrical conductivity was investigated. Besides, the mechanism of RGO on composite conductive concrete's conductive network was analyzed by scanning electron microscope (SEM). Results showed that the 28-day mechanical properties and electrical conductivity of composite conductive concrete first increased and then decreased. Composite conductive concrete containing RGO with 0.4% cement weight (RGO-0.4) exhibited better mechanical and electrical properties. The improvement of the performance of composite conductive concrete was attributed to the filling effect of RGO on the gaps of concrete matrix and the wrapping effect of graphene flocs on fibrous conductive fillers because these effects increased the compactness of the matrix and conductive contact area, respectively. Also, a snow melting test was carried out using an RGO-0.4 slab at an ambient temperature of −15°C. The snow melting efficiency was improved, showing that 20-cm-thick snow melted in 1.2 h. In conclusion, the hybrid addition of RGO and fibrous conductive fillers has positive effects on ECON, providing a new way to develop ECON. [ABSTRACT FROM AUTHOR]

This work assessed the effect of compressive fatigue on sulfate ion diffusion in standard-cured and steam-cured concrete containing slag. After compressive fatigue, the slag concretes were immersed in 5% sodium sulfate solution for 18 months. The sulfate ion content in concrete was measured and the sulfate ion effective diffusion coefficient was calculated. The results showed that compressive fatigue accelerated sulfate ion diffusion in concrete, and the acceleration was more prominent in steam-cured concrete than standard-cured concrete. During sulfate attack, the sulfate ion content in the same layer of standard-cured fatigued concrete grew with an increase in stress level. Massive ettringite with large size was generated in steam-cured fatigued concrete during sulfate attack. In addition, a sulfate ion diffusion model of fatigued concrete was established. Based on this model, the measured values agreed well with the simulated distribution curve of sulfate ions in fatigued concrete. [ABSTRACT FROM AUTHOR]