Self-monitoring of fatigue damage in carbon fiber reinforced cement

Self-monitoring of slight fatigue damage was demonstrated in cement mortar containing short carbon fibers (0.24 vol.%), as damage (occurring in the first < 10% of the tensile or compressive fatigue life) caused the volume electrical resistivity to decrease irreversibly by up to 2%. The greater the stress amplitude, the greater the damage, the greater the resistivity decrease and the greater the number of stress cycles for which the resistivity decrease monotonically occurred. The resistivity decrease is attributed to the damage of the cement matrix separating adjacent fibers at their junction.