Definition - What does Surface Hardener mean?
A surface hardener is a formulated chemical compound (silicate liquid) that is used after pouring concrete to increase the concrete's hardness, reduce the concrete's permeability and to dustproof the concrete as it solidifies. Surface hardeners provide a cost-effective solution to improve the service life of the concrete surface and protect it from abrasion, dusting, pitting and chipping.
Surface hardeners are also known as densifiers.
Corrosionpedia explains Surface Hardener
Surface hardeners are applied to a concrete surface after it is smoothed and left to dry. They help to improve the concrete's abrasion and chemical resistance, thus significantly improving the durability of the concrete surface. Surface hardener liquids penetrate inside the concrete surface, reacting with it and producing a by-product that fills the pores of the concrete. This also helps to reduce the permeability of the concrete.