Concrete hardeners increase the surface strength of the concrete by reducing the density of the concrete pores. The most common type of concrete hardeners are sodium silicates and lithium silicates.
How Concrete Hardeners Work
Unlike other types of concrete sealers, concrete hardeners are not left in or on the concrete. Instead, they spark a chemical reaction that creates calcium silicate hydrate (crystalline barrier) within the pores. Once the chemical reaction takes place and the calcium silicate hydrate is formed, there is no sealer left. The calcium silicate hydrate formed from the silicate reaction is permanent. The barrier can only be removed when the concrete itself is removed.
How Deep to Concrete Hardeners Penetrate?
The calcium silicate hydrate barrier formed by one sealer is identical to the calcium silicate hydrate formed by another. In an effort to market their products differently, many manufacturers will emphasize penetrating depth. The truth is, the sealer doesn’t control penetration depth – the concrete does. Dense concrete will absorb less material than porous concrete. Silicates will penetrate up to 1″ on dense concrete, and up to 6″ on porous concrete. It is also important to consider the fact that penetration depth doesn’t necessarily mean barrier thickness. The amount of material applied, and the amount of free lime and calcium present in the concrete determine the thickness of the barrier. This is why multiple coats may be required to achieve the desired level of hardness on the surface. Silicate sealers spark a chemical reaction, but the results of that chemical reaction can’t be predicted or controlled.
What is the Best Concrete Hardener
As mentioned above, all silicate sealers product the same calcium silicate hydrate barrier within the pores. When choosing the best concrete hardener, there are a few things to consider:
- Concentrated vs. Pre-diluted: Simply put, when you pay for a concentrated silicate you are paying for silicate, and when you are paying for a pre-diluted silicate you are paying for silicate and water. It is more cost effective to purchase a concentrated silicate and add water on-site.
- Sodium silicate vs Lithium Silicate: Both types of concrete hardeners are great. Sodium silicate sealers react slower than Lithium silicate sealers, but the reaction is identical. It is very common to use sodium silicate sealers on porous concrete or concrete where water/moisture are present, and lithium silicate sealers on dense concrete or concrete that is being polished.
Best Sodium Silicate Concrete Hardeners
- Armor S2000 Concrete Sealer Review (concentrated)
- RadonSeal Concrete Sealer Review (pre-diluted)
- Stone Technolgies X-1 Concrete Sealer Review (pre-diluted)
- Ashford Formula Concrete Sealer Review (pre-diluted)
Best Lithium Silicate Concrete Densifiers
- Armor L3000 Concrete Sealer Review (concentrated)
- PS103 Concrete Sealer Review (pre-diluted)
- Lion Hard Concrete Sealer Review (pre-diluted)