*2.5. Dielectric and Electric Measurements*

For the present samples, the capacitance effect (*Cp*), electric loss tangent (*D*), and electric resistance (*Rp*) were measured in a parallel series using a computerized LCR Hitester impedance bridge (IM3536) in the range of 50 Hz–8 MHz at 350 AC frequency points. Then, the dielectric constant (*ε* ), dielectric loss (*ε*), imaginary part (*M*) of the complex electric modulus, and electric conductivity (*σ*) were estimated as follows:

$$
\sigma = \frac{L}{A \times R\_P} \tag{2}
$$

$$
\varepsilon' = \frac{\mathbb{C}\_P \times L}{A \times \varepsilon\_0} \tag{3}
$$

$$
\varepsilon'''' = \varepsilon' \times D \tag{4}
$$

$$M^{\prime\prime} = \frac{\varepsilon^{\prime\prime}}{\varepsilon^{\prime2} + \varepsilon^{\prime\prime2}} \tag{5}$$

where *ε* is the dielectric constant, *Cp* is the electric capacitance in parallel, *L* is the sample thickness, *A* is the contact area of the measuring non-polarized electrode, *ε* is the dielectric loss, *<sup>ε</sup><sup>o</sup>* is the dielectric constant of the air (8.85 × <sup>10</sup>−<sup>12</sup> F/m), *<sup>D</sup>* is the measured electric loss tangent (tan *δ*), RP is the measured electric resistance in parallel, *σ* is the electric conductivity, and *M* is the imaginary electric modulus.

More details on the applied techniques are discussed by many authors [35–37].

For determining the implications of different sintering temperatures on the electric and dielectric properties of the studied samples, three samples of the same composition (50% arc furnace ceramic slag + 50% sludge; AFS5), were sintered at 1050 ◦C, 1100 ◦C, and 1150 ◦C. Then, their density, porosity, and electric and dielectric parameters were measured.

#### **3. Results and Discussions**
