Research on the self-sensing and mechanical properties of aligned stainless steel fiber-reinforced reactive powder concrete

Stainless steel fibers (SSFs) were added into reactive powder concrete (RPC) to fabricate aligned (improved by Lshaped device) and random directional distributed SSFs conductive RPC. The aspect ratio of SSFs ranged from 30 to 150, while the SSFs amount was 0.2%?1.2% by volume of RPC. Curing ages for RPC ranged from 7 d to 60 d. The conductive performances (electrical resistance and AC impedance spectroscopy), the speed of ultrasonic passing through specimens and the following piezoresistivity were investigated. Moreover, the compressive strength, flexural strength and toughness of specimens cured for 60 d were tested. Finally, high-resolution images of SSFs? dispersion and orientation were gained. Results showed that the ultrasonic velocity and electrical resistance of SSFs-RPC grew in the form of a quadratic function with the increasing curing ages. The SSFs content of 0.4% was the percolation threshold value of SSFs-RPC. Additionally, RPC with higher aspect ratio and aligned fibers performed better conductivity, piezoresistivity and mechanical performance. The conductive mechanism of SSFs-RPC can be explained through the conduction models of three series connected electrical components. The image analysis showed that SSFs with higher aspect ratio dispersed more uniformly in RPC and the L-shaped device could effectively improve the alignment of fibers.

Automated summary

The addition of stainless steel fibers (SSFs) in reactive powder concrete (RPC) significantly influences the electrical and mechanical properties of the material, with factors such as SSFs content, aspect ratio, and orientation playing important roles in determining performance. The interaction between these different factors is complex and can lead to variations in conductivity and piezoresistivity.