Understanding the zinc incorporation into silicate clinker during waste co-disposal of cement kiln: A density functional theory study

Zinc ion, as inevitably incorporated into cement clinker during the waste co-disposal of cement kiln, has conspicuous influence on the phase composition and properties of clinker minerals. The present study employs the state-of-the-art density functional theory calculation to clarify the mechanism of zinc incorporation into clinker crystals at the atomic level. We theoretically predicted the substitution preference of zinc ions in silicate clinker phases, which is in good agreement with previous experimental results. Furthermore, it finds that the zinc substitution preference is mainly governed by the overall crystal deformation and local structural distortion. Herein, two indicators defined as “relative volume changes” and “bonding structure difference” are proposed to characterize and predict zinc-doping mechanism in silicate clinker phases, which performs much better than previous indicators such as “ionic radius” and “structure difference factor”. This theoretical method is supposed to be generalized to investigations of other chemical impurities and clinker systems, which facilitates the design and modification of doping-enhanced cementitious materials.