Mechanisms of cement hydration

Abstract To better understand the influence of concrete admixtures on the properties of the fresh and hardened concrete, it is important to have a good comprehension of the physical and chemical processes of cement hydration. Ordinary Portland cement (OPC) hydration involves mechanisms of dissolution and precipitation in a complex chemical system composed of different mineral phases, resulting in the formation of different hydrates. This leads to the setting and the hardening. The main objective of this chapter is to describe the fundamental steps that have been made recently in the comprehension of the different hydration processes and to present important points that are still subjects of debate. This includes the description of the hydration stages of the main phases (aluminates, silicates, and sulfates), as well as the importance of their balance and interaction during cement hydration.