Advances in dissolution understanding and their implications for cement hydration

Abstract

Recent advances in bridging kinetics and thermodynamics of mineral dissolution have opened new horizons in our understanding of the role of dissolution in cement hydration. Indeed most hydration kinetic regimes of alite can be rationally envisioned from a dissolution perspective. This short note reviews some key findings on dissolution mechanisms and their implication for cementitious systems.

Hydration of Portland cement accelerated by C-S-H seeds at different temperatures

“…Apparent activation energy (E a ) results and correlation coefficients (r 2 ) obtained from the fitting of a linearized Arrhenius equation at α = 0.5 for all pastes blended with C-S-H seeds. Nevertheless, it should be noted that some authors have proposed a two-step nonclassical nucleation process for C-S-H, where C-S-H would not serve as substrate for heterogeneous nucleation; thus, expecting that C-S-H will precipitate around the anhydrous grains even at high dosages of C-S-H seeds [26,29]. The effect of C-S-H seeds over the hydration kinetics was also studied through the setting and hardening processes.…”

Effects of sulfates on the hydration of Portland cement – A review

“…In addition, gypsum (and other soluble sulfates salts as Na 2 SO 4 ) influence the C 3 S hydration. Gypsum retards the initial hydration of C 3 S, and a more extended induction period is observed [6,8,11,17]. According to Nicoleau et al [11] and Juilland et al [17] the sulfate ions are physically adsorbed on C 3 S surface, decreasing the surface charge and lowering its dissolution rate.…”

“…Although not as heavily investigated as C 3 A-calcium sulfate systems, calcium sulfate also changes the C 3 S hydration, the morphology of its hydration products, and its mechanical strength [6,8,11,[17][18][19]. The effect of calcium sulfate on C 3 S hydration needs to be properly understood as it can influence the sulfate optimization in Portland cements and, therefore, can influence cement properties.…”

Advances in characterizing and understanding the microstructure of cementitious materials

“…A direct experimental evidence showed that silicate dissolution is reduced by the presence of PCEs [131]. The fact that low dosages of polymer may effectively block the dissolution of a reactive phase may be understood from the perspective of blocking reactive surface areas on the surface, that are generally etch pits, or modifying the kinetics and the way they expand (Figure 16) [131,192]. As a confirmation, the exact same rate of reaction, and therefore retardation, was observed between a C3S with PCEs and the same C3S but annealed to remove defects on the surface [131].…”

“…a) Schematic representation of growth of etch pits in the absence and presence of PCEs adsorbed on the surface of tricalcium silicate close to the etch-pit, b) heat flows of a pure tricalcium silicate without and with PCE, and after annealing. Reproduced and adapted from [131] and [192].…”