How Does Lithium Concrete Densifier Work?

Curing

• Concrete curing or hardening is a chemical process in which water reacts with compounds in the cement mixture to make calcium silicate hydrate. Excess calcium hydroxide or "free lime" is a byproduct of the reaction. This free lime is normal but can in some cases accelerate deterioration of the concrete surface over time. Densifiers or hardeners contain silicate compounds that react with the free lime to form additional silicate hydrates near the concrete surface.

Lithium

• Densifiers may consist of either sodium, potassium or lithium silicates. The lithium, sodium or potassium is found in the form of a positively charged ion connected to a negatively charged silicate ion by an ionic bond. The lithium does not play any direct role in the chemical reaction that takes place once you apply the densifier. One byproduct of the reaction, however, is the formation of lithium, potassium or sodium hydroxides, and these must be removed after densifier application.

Benefits

• The reaction takes place in pores or capillaries in the concrete's surface, so these pores become filled up, making the concrete denser and harder. Typically the densifiers only penetrate to a shallow depth, but by so doing they change the properties of the surface layer. Lithium silicates tend to be more expensive than the alternatives, but they are also effective at slightly lower concentrations, so there are some trade-offs involved.

Considerations

• Lithium densifier should never be applied to wet concrete that has not cured yet -- the pores are already full of water and the lithium densifier will achieve little if anything at this stage. Densifier application can help make the concrete more resistant to stains by making it more impermeable. It can also help improve abrasion resistance and prepare the surface for polishing, which is why densifiers are often applied as part of the polishing process.