Electrical-resistance-based damage self-sensing in carbon fiber reinforced cement

Damage self-sensing (to be distinguished from strain self-sensing) by electrical resistance measurement is effective in carbon fiber reinforced cement below the percolation threshold, as shown under uniaxial compression. Major damage that is accompanied by irreversible strain is indicated by irreversible resistivity increase ranging from 10% to 30%. Minor damage in the elastic regime is indicated by this increase ranging from 1% to 7%. The irreversible resistivity fractional change per unit irreversible strain is higher in the transverse direction than the longitudinal direction. The origin of the damage self-sensing ability is attributed to the fracture of fibers that bridge microcracks and the consequent resistivity increase. The fracture of a bridging fiber occurs upon microcrack opening or shear.