ε= ε ε,
0
μ = μ, σ= 2πfε tanδ (2)
The composite materials of cement paste are non-magnetic.
Therefore, the materials effect is negligible, as is true for most dielectric
materials used in microwave heating. The cement paste’s magnetic
permeability (μ) can be approximated by
0
μ in the free space
(4x10
−7
H/m).
The boundary conditions associated with the physical model as
shown in Fig. 2, are as follows [12]:
(a) Perfectly conducting boundaries. Boundary conditions on the
inner wall surface of a rectangular wave guide are given by using
Faraday’s law and Gauss theorem:
0, 0
t n E H
(3)
(b) Continuity boundary condition. Boundary conditions along the
interface between different materials, for example between air and
dielectric material surfaces, are given by using Ampere’s law and Gauss theorem: