Self-sensing capabilities in steel fiber-reinforced concrete for shrinkage resistance and structural health monitoring.

Shrinkage-induced cracking compromises concrete durability, while structural health monitoring typically requires external sensors. This study demonstrates that steel fiber-reinforced concrete (SFRC) can simultaneously mitigate shrinkage and enable intrinsic self-sensing. Sixteen beam specimens (C30 and C35) were cast with 50 mm and 60 mm steel fibers (SF) at dosages of 0.19%, 0.26%, 0.32%, and 0.38%. Shrinkage strain and fractional change in resistance (FCR) were monitored for 180 days and 72 h, respectively. Results shows that 60 mm SF at 0.38% reduced 180-day shrinkage strain by up to 38%. C30 beams with 50 mm SF exhibited peak FCR values of 181%, whereas C35 beams with 60 mm SF reached 128%. A strong positive correlation (R² = 0.90-0.98) was observed between FCR and shrinkage strain, confirming reliable self-sensing capability. The FCR rate of change decreased from 0.998%/h to 0.303%/h with higher SF dosage and length, indicating improved early-age stability. These findings confirm that optimized SFRC mixtures offer dual functionality which are effective in shrinkage control and real-time health monitoring, making them ideal for applications like industrial floors and tunnel linings where crack resistance and self-diagnosis are critical.