Predicting Hydration Reactivity of Cu-Doped Clinker Crystals by Capturing Electronic Structure Modification

Chemical doping is a promising scheme for sustainable development of green and economical cement manufacturing related to global energy and environmental concerns. Understanding and controlling doping effect on reactive cement components is the prerequisite. This study aims to propose effective theoretical methods to reveal the correlation between hydration reactivity of doped clinker crystals and their electronic structures. Four dominant Portland cement clinker phases with copper doping are comparatively investigated by the state-of-the-art ab initio calculation. It finds that Cu ions doped in silicate and aluminate phases shift the nucleophilic reactive sites from Ca-centered regions to defect sites by decreasing the effective charges of Ca ions, which accounts for the hydration retardation of these phases. Exceptionally, the reactive sites in ferrite phase are scarcely changed by Cu doping due to the intense band-edge localization of Fe 3d state, which implies the relatively lesser influence on hydration reactivity. The corresponding experiments of the ion release rate of clinker phases during early hydration process as captured by the conductivity meter and inductively coupled plasma-optical emission spectrum strongly support our computational results. Our theoretical calculations provide a powerful method to predict the early hydration reactivity of clinker minerals and enrich the understanding of early hydration characteristics and its variations.