Fatigue damage self-sensing of bridge deck component with built-in giant piezoresistive Cementitious Carbon Fiber Composites

Piezoresistive cementitious composite materials are promising for developing damage self-sensing structural components. This paper aims to develop a kind of giant piezoresistive Cementitious Carbon Fiber Composite (CCFC) for enabling a fatigue damage self-sensing bridge deck. In particular, 0.4 % and 0.8 %Vol. of short cut Carbon Fibers (CFs) in cementitious composite were respectively adopted. The fiber diameter and length were 7 mu m and 3 mm. Based on a series of conducted material piezoresistivity tests, the material effective conductivity variation showed a linear response with a slight time delay to an external load induced compressive strain. The gauge factors of CFCC with 0.4 % and 0.8 %Vol. CFs were respectively above 6000 and 2000. Moreover, the effects of ambient temperature, humidity and polarization were investigated, and a linear relationship between the ambient temperature and the effective conductivity was regressed. Accordingly, CFCC blocks were cast and built into two full-scale segmental bridge deck specimens for a fatigue wheel loading test. The correlation between the CFCC effective conductivity and the fatigue damages, such as concrete cracks, deflections and strain, was discussed. The results confirmed a feasibility of using the giant piezoresistive CCFC to develop a bridge deck with damage self-sensing capability.