*3.4. Electrical Resistivity ρ (k*Ω*-cm)*

The electrical resistivity of biochar-concrete and the control specimen is displayed in Figure 9. It is indicated that the electric resistivity *ρ* decreases gradually with increased biochar content. The value of electric resistivity was recorded as 26.1 kΩ-cm for the control mix. The values of electric resistivity noticed for 0.25%0.50%,0.75%,1.00%,1.50% biochar-concrete specimen was 22.4,22.2, 20.9,19.6,16.5kΩ-cm, respectively, which indicate linear decrease in the values of electric resistivity. Any material's electrical resistivity (*ρ*) is described as its ability to resist the ions transfer exposed to an electrical field. It mainly relies on the microstructure elements associated with the shape of interconnection and pore size [39]. A finer pore network with fewer connections results in lower permeability, leading to increased electrical resistivity [40–42].

**Figure 9.** Electric resistivity of different concrete samples.
