Self-monitoring of freeze–thaw damage using triphasic electric conductive concrete

• The mass loss and FCI of conductive concrete during freeze–thaw cycles was studied.
• Macro steel fibers as structural materials can enhance the toughness strongly.
• Macro steel fibers and micro carbon fibers as function materials can improve the conductive network of concrete.
• The relationship between the FCI and freeze–thaw cycles of conductive concrete was suggested.
• We can evaluate the freeze–thaw damage of concrete by measuring the FCI.

The effect of freeze–thaw cycles on concrete is of great importance for durability evaluation of concrete structures in cold regions. In this paper, damage accumulation was studied by following the fractional change of impedance (FCI) with number of freeze–thaw cycles (N). The nano-carbon black (NCB), carbon fiber (CF) and steel fiber (SF) were added to plain concrete to produce the triphasic electrical conductive (TEC) and ductile concrete. The effects of NCB, CF and SF on the compressive strength, flexural properties, electrical impedance were investigated. The concrete beams with different dosages of conductive materials were studied for FCI, N and mass loss (ML), the relationship between FCI and N of conductive concrete can be well defined by a first order exponential decay curve. It is noted that this nondestructive and sensitive real-time testing method is meaningful for evaluating of freeze–thaw damage in concrete.