A densifier is substance applied to surface of concrete in order to fill pores and increase surface density. They are chemical solutions designed to improve concrete’s surface hardness, density and shine. They react with free lime and calcium hydroxide present in the concrete. This solidifies it, making the concrete surface much less permeable and more resistant to stains.
Where is a densifier used?
The most common uses include hard troweled industrial floors, polished concrete (before polishing) and decorative concrete (before being decoratively stained.)
Why is a densifer needed?
Densification is the process of permanently closing pores in the top layer of the slab. Since concrete is extremely porous it is susceptible to staining and vulnerable to acid attack that may cause surface etching. Surface wear and dusting are natural characteristics of concrete that need to be considered when deciding to seal concrete. Since concrete is weak densifiers, hardeners, additives, and protectors are used to help resolve these issues.
Types of densifiers:
Densifiers are classified into two “generations.” Magnesium, potassium and sodium silicate are first-generation products and react with the calcium hydroxide in the concrete. The reaction starts immediately but continues slowly, due to the natural closeness of the pH of concrete. This application process is more caustic and labor-intensive.
Second-generation densifiers are lithium silicate-based densifiers with nano-sized technology and waterborne colloidal silica from nano-sized particles. The lower pH of this colloid makes the reaction much faster and increases more reaction points with the free lime in the concrete. Plus, the suspension of the silicate particles allows the solution to penetrate much deeper before this reaction takes place.