Cement hydration Part III: Tips & tricks for a better degree of hydration

There are some tips & tricks how to improve cement hydration degree in concrete in general, and especially in semi-dry concrete. We would like to present these to you in the following.

Use finer cement!

Cement particles dissolve from the outside in. The reactions gradually slow down as cement stone forms and harden and access to new water becomes more difficult. Smaller particles with more surface area hydrate faster and more completely. This is the principle of high strength rapid cement. Their main downside is a higher price and faster heat development.

Prevent water loss!

Preventing the evaporation of mixing water is one of the simplest practices for maximizing cement hydration.

- Self-curing: Some types of porous aggregates and absorbent additives can “hold” the water inside, slowly releasing it during the hydration stage as necessary. Among such materials belong for example lightweight aggregates (expanded clays, sintered fly ash, granulated blast furnace slag, slates, perlite, vermiculite and more), super-absorbent polymers (polyacrylamides, polyacrylates) and also certain shrinkage reducing admixtures.

- External curing: A more common type of concrete curing using impermeable membranes or coatings (Emcoril).These products not only prevent water evaporation, but also protect the delicate surface of hardening concrete, which leads to harder, more durable and aesthetic pleasing surface. Curing agents are applied on the concrete surface immediately after casting and finishing.

Provide warm and humid environmental conditions!

Water evaporation is a process driven by a concentration gradient. The less humid the environment, the faster the evaporation from concrete. Because the ability to “hold” more water vapour increases with temperature, a warm and humid curing environment is ideal for undisturbed cement hydration. Obwohl die Zementhydratation als exotherme Reaktion angesehen wird und daher "ihre eigene Wärme erzeugen kann", trägt die Temperatur der Umgebung nicht nur zur Aufrechterhaltung einer hohen relativen Luftfeuchtigkeit bei, sondern auch zu einer schnelleren Hydratation und damit zu einer kürzeren notwendigen Nachbehandlungszeit.