Abstract
Two distinct slopes (resistances) are obtained in current-voltage (I-V) plots of discontinuous, conductive fiber-reinforced cement composites. The low-field resistance correlates with the DC resistance (RDC) of each composite. The high-field resistance correlates with the intermediate frequency cusp resistance (Rcusp) in Nyquist (-Zimag vs. Zreal) plots obtained using impedance spectroscopy (IS). A model is developed that is based on passive oxide film formation on copper or steel fiber surfaces at low fields (I-V) or low frequencies (IS) due to the high pH pore solution of cement paste. With increase of field, leading to film breakdown (active or transpassive corrosion behavior), or increase of frequency, leading to short-circuiting of the passive layer, the fibers act as short-circuiting elements in the composite microstructure, resulting in a decrease in overall resistance.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 835-840 |
| Number of pages | 6 |
| Journal | Cement and Concrete Research |
| Volume | 33 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 2003 |
Funding
This work was supported by the National Science Foundation under grant no. DMR-00-73197 and made use of facilities of the Center for Advanced Cement-Based Materials.
Keywords
- Composite
- Electrical properties
- Electrochemical properties
- Portland cement
- Reinforcement
ASJC Scopus subject areas
- Building and Construction
- General Materials Science