Volume electrical resistivity of carbon fiber cement composites

The results of some fundamental investigations on the bulk electrical prope rties of carbon fiber cement composites (CFCCs) are presented with the pros pect of developing a new nondestructive testing method to assess the integr ity of the composite. The addition of carbon fibers to portland cement-base d concrete or mortar improves the structural performance and at the same ti me significantly decreases the bulk electrical resistivity This makes CFCC responsive to interrogation by electrical methods. Three different electrod e configurations were investigated for their applicability in measuring ele ctrical resistivity of CFCC specimens. The Volume electrical resistivity of CFCC specimens was recorded as a function of curing time. The dependence o f this electrical resistivity on the water-cement ratio (w/c), sand-cement ratio, volume fraction of carbon fibers in the mixture, and the length of f ibers was determined. The reliability of measurements performed using both DC and AC was evaluated. The relationships between resistivity and both tem perature and relative humidity were also investigated.