Optimising Early Hydration and, CO2 Sequestration of Ternary Cement Using 2D Materials: Dispersion optimisation of 2D materials, and its impact on hydration kinetics

Abstract

Given the substantial contribution of cement production to global CO₂ emissions, advancing the sustainability of cement materials is imperative. This research addresses the challenge of low early strength in blended cements by exploiting the unique properties of 2D materials to accelerate hydration and improve mechanical performance. This study investigates the enhancement of early hydration kinetics and CO₂ sequestration in ternary cementitious system through the incorporation of two-dimensional (2D) materials, specifically graphene oxide (GO) and graphene nanoplatelets (GNPs). A central aspect of using 2D materials within the cement matrix is its dispersion state, a critical factor in maximizing their benefits. To overcome its agglomeration, physical and chemical dispersion techniques were employed, including the use of polycarboxylate ether (PCE) as a dispersant, ultrasonication, and grinding. Isothermal calorimetry and in-situ X-ray diffraction (XRD) were utilized to analyse hydration kinetics of binder. Results indicate that GO with a PCE/GO mass ratio of 10 achieves superior dispersion in pore solution, with a significant enhancement in hydration kinetics of ternary binder. The incorporation of 0.1 wt. % GO resulted in notable increases in compressive strength of 22%, 24%, and 19% at 1, 3, and 7 days, respectively, compared to the control samples. However, higher GO concentrations, such as 0.4 wt. %, led to reduced strength. XRD analysis further revealed that GO with PCE as dispersant accelerates the precipitation of hydration products. An incorporation of 0.1 wt. % GO also induces an increase in carbonation rate by 83.7%. Despite this effect on kinetics, thermogravimetric analysis (TGA) demonstrated that its effect on CO₂ uptake capacity is negligible. Additionally, although GNPs exhibited a better dispersion sate, but they suppress hydration kinetics. These findings underscore the potential of GO in accelerating early strength development and enhancing carbonation rates in cement systems.