Alternative concrete sealant
Concrete sealants can be categorised as organic (normal sealers) and inorganic.
− Organic concrete sealants include acrylic sealers, epoxy coatings, urethane sealants, polyureas, polyaspartics and a host of other genres that are characterised by a film of sealant on the surface of the concrete, held there by a mechanical bond.
− Inorganic concrete sealants are derived from natural compounds from the earth such as minerals and chemically react with the concrete to form a permanent bond to repel dirt and liquids without a film on top of the concrete.
These inorganic concrete sealants are an alternative to a glossy coating that require less effort, are less toxic, have no VOC’s, are less expensive and easier to apply as well as being more permanent. Most do not produce a shine or alter the appearance of concrete, however they seal off capillaries in concrete floors which slows down the penetration of fluids and dirt.
Preparation is less important to achieve a successful floor as long as it is free of other sealers or curing compounds. If preparation is required see Concrete Garage Floor Coating for methods.
These inorganic concrete sealants come under the genre of concrete hardeners and densifiers as used by the concrete polishing industry today and comprise four main types with different properties which are:
1. Magnesium Fluorosilicates
2. Sodium Silicates
3. Potassium Silicates
4. Lithium Silicates
This is the only hardener that will harden the paste on top of the slab and requires multiple applications.
These are the least expensive, do not penetrate deeply, will not bead water and they used to make up over 90% of the floor hardeners available in USA. Typical application is by mechanical action to break down the surface tension, misting with water to reform a gel, then rinsed and wet vacuum removed. The white salt after application especially on new concrete will have to be mechanically removed with high pressure water of it looks unsightly.
Better for old worn concrete, more expensive than Sodium Silicates, deeper penetration except in dense substrates, will not cause white salts to appear, can expand internally causing map cracking on the surface and represented about 3% of the water based mineral concrete sealants available in USA.
These were mainly developed to counter the expanding properties of the above which can cause cracking of the surface. They are also non soluble so ground water will not interfere and the concrete will not absorb water. The smaller ions allow deeper penetration, especially in dense concrete, efflorescence is invisible so it is not a problem, and it is unaffected by salt spray. The application procedure by light spray is less sensitive too.
The above concrete sealants are a good alternative to organic coatings and should be considered for many concrete surfaces because they inhibit the entry of fluids and stop dusting, but they cannot be worn away.