Electronic, elastic properties and thermal conductivity of the major clinker phases of portland cement: Insights from first-principles calculations

摘要

We present a comparative study between the structural, electronic, elastic properties, and thermal conductivity of cement compounds (Ca3SiO5:C3S, Ca2SiO4:C2S, Ca3Al2O6:C(3)A, and Ca2AlFeO5:C(4)AF) using first-principles calculations based on density functional theory. The calculated structural properties are in good agreement with the experimental data. The electronic properties of cement compounds are mainly contributed from the O-2s and Ca-3d orbitals due to the strong ionic character. Herein, C3S and C2S are insulators, with respective band gap energy of 3.34 and 5.217 eV. Moreover, the cement compounds manifest anomalously ultra-low thermal conductivity due to reduced Debye temperature and hardness. In the comparison, the highest thermal conductivity of C(4)AF compound was up to 2.423 W m(-1) K-1, which is similar to 11 times higher than that of C2S (0.218 W m(-1) K-1). Further, the hydration mechanism is described by understanding the interaction of water molecules on beta-C2S low-index and M3-C3S highly reactive surfaces.

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