Effects of temperature and stress on the interface between concrete and its carbon fiber epoxy-matrix composite retrofit, studied by electrical resistance measurement

DC electrical resistance measurement was used to investigate the effects of temperature and stress on the interface between a concrete substrate and its carbon fiber epoxy-matrix composite retrofit. The apparent resistance of the retrofit in the fiber direction was increased by bond degradation, whether the degradation was due to heat or stress. The degradation was reversible. Irreversible disturbance in the fiber arrangement occurred slightly as thermal or load cycling occurred, as indicated by the resistance decreasing cycle by cycle.