External erosion of sodium chloride on the degradation of self-sensing and mechanical properties of aligned stainless steel fiber reinforced reactive powder concrete

Electrical parameters (electrical resistance and AC impedance spectrum) of stainless steel fibers reactive powder concrete (SSFs-RPC) were investigated. Aspect ratios of SSFs were 60 and 150. All specimens were subjected to freeze–thaw cycles and dry-wet alternations of 3.0% NaCl solution. The velocity of ultrasonic wave through specimens, the electrical resistance, the AC impedance spectroscopy and the following piezoresistivity were analyzed. Besides, high resolution images were tested to study the damage and corrosion of SSFs in RPC. The results indicated that little spalling occurred on the surface of specimens after freeze–thaw cycles and dry-wet alternations of NaCl solution. RPC with higher aspect ratio and dosages of SSFs showed better attenuation resistance. Electrical resistance and AC impedance spectroscopy were effective to monitor the deterioration degree of SSFs-RPC when applied in the alternate environment of freeze–thaw and dry-wet of NaCl solution. SSFs-RPC with SSFs dosage of 1.2% by the volume of RPC and SSFs aspect ratio of 150 behaved the optimum durability and piezoresistivity. Aligned SSFs demonstrated positive roles on the electrical conductivity, the piezoresistivity and the resistance to alternations of freeze–thaw and dry-wet in NaCl solution.