Triple percolation in concrete reinforced with carbon fiber

The electrical resistivity of carbon fiber (CF) reinforced concrete with electrical continuity within the cement paste and sand-cement ratio (s/c) 0.75 depends on the CF content and gravel-sand ratio (g/s). For resistivity ≤500 .cm, the mortar must exceed 62 vol.% and the cement paste must exceed 44 vol. %. The minimum resistivities provided by double percolation (continuity provided by the cement paste in the mortar but no continuity of either paste or mortar), pseudo triple percolation (continuity provided by the cement paste of the mortar), and true triple percolation (continuity provided by the mortar) are 355, 36, and 7.6 .cm, respectively. The true triple percolation threshold is 0.75% CF (by mass of cement) if g/s ≤1.50 and 1.5% CF if g/s ≤2.00. The pseudo triple percolation threshold is 1.5% CF if g/s = 2.50 and 1.75% CF if g/s = 2.50 to 3.00. The double percolation threshold is 0.75% CF if g/s = 2.00 to 3.00.