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

We present a comparative study between the structural, electronic, elastic properties, and thermal conductivity of cement compounds (Ca₃SiO₅:C₃S, Ca₂SiO₄:C₂S, Ca₃Al₂O₆:C₃A, and Ca₂AlFeO₅:C₄AF) 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 C₄AF compound was up to 2.423 W m⁻¹ K⁻¹, which is ∼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 β-C₂S low-index and M3-C₃S highly reactive surfaces. © 2023 Elsevier Ltd.