A new trend that has been finding its way onto the surface of garage floors and shop floors is the use of a concrete densifier and sealer. Densifiers have been used on occasion in the garage for a variety of reasons, but rarely as an actual finished garage flooring treatment. So why has there been a gradual increase in its use and popularity for the garage floor?
The reason is the addition of silicone and siliconate agents in some densifiers to act as a sealer. This helps to create not only a water repellant floor, but one that is resistant to liquids and chemicals in general. So let’s take a closer look at how a concrete densifier with sealer on your garage floor may be beneficial for you.
How a concrete densifier works on a garage floor
Concrete densifiers have been around for decades. They are a concrete hardener that have been used in the flooring industry primarily for concrete floor polishing, increased abrasion resistance, anti-dusting, and moisture mitigation. In some cases it is used to harden softer concrete surfaces before grinding. They are typically applied to machine troweled, hard troweled, and smooth concrete.
When concrete cures, bleed water makes its way to the surface and increases the water to cement ratio. The result is an increase in laitance content, and fine aggregates. This is what helps to make the surface of concrete smooth, but it also creates a surface that is softer than the underlying cement. When a densifier is introduced, a chemical reaction is created that increases the surface strength of concrete from an average of 20% to 40% depending on the original pour and finish of the concrete.
Densifiers are a water based chemical solution that first works by penetrating into the surface of the concrete and reacting with calcium hydroxide to produce calcium silicate hydrate (CSH). This is the substance that gives concrete its strength. Next, the CSH that is produced fills the open pores and capillaries of the concrete, thus increasing the density and strength.
Lithium densifiers are the most common choice used for garage floors. This is due to their ease of application and less reactive properties to carbon dioxide which can create a whitening effect on the floor. Unlike sodium densifiers, lithium densifiers also do a good job at repelling road salts. Once applied, the concrete retains its natural matte look.
It’s important to note that concrete densifiers are non-film forming, meaning that they don’t leave a topical film on the surface to protect it from liquids and staining. Densifiers are technically not a water repelling sealer as well. They don’t form a molecular membrane at the surface that repels liquids. This is why they haven’t been used much as a finished product for garage floors – until recently.
The addition of silicone and siliconate agents in densifiers has changed this. They create a waterproofing agent right at the sub-surface of the concrete. This addition allows the densifier to act as a sealer for your garage floor by repelling water, oils, chemicals such as road salts, and other fluids.
Are they 100% impervious to stains and chemicals? No, but if you don’t allow spills to sit for a long period, they will generally wipe right up with little if any scrubbing necessary. Be particularly careful with solvents that can stain, as their resistance to them is minimal.
The benefits of a concrete densifier with sealer include:
- Added strength and abrasion resistance to the surface of a working garage
- Increases the compressive strength of concrete
- Repels liquids and other fluids which help to make your garage floor stain resistant
- Eliminates dusting and problems with efflorescence
- It doesn’t peel, leave tire prints, or turn yellow
- Helps act as a moisture barrier for your garage floor
- Improves weathering and resistance to freeze/thaw effects
- Non-slip surface
- Relatively inexpensive
- Lasts for years without need of reapplication
- Easy to apply and is ready for traffic within an hour or two
Concrete densifier sealers we recommend
One particular densifier sealer that we recommend is PS104 by Concrete Sealers USA. This is the same company that manufacturers the very highly rated PS101 siliconate sealer which we have discussed before.
With an average coverage rate of 200-300ft², it is now available in 1 gallon containers as well as their 5 gallon containers.
What we like about PS104 is the amount of lithium silicate (measured in solids content) that is used. Manufacturers generally have to perform a balancing act between how much lithium silicate can be included for densifying purposes and how much siliconate can be added for sealing the surface.
If too much lithium silicate is used, it makes it difficult to add the required amount of siliconate for sealing. It also makes the product more expensive. As a result, many of the densifiers with siliconate sealer added have a lower solids content of the lithium silicate in order to keep the price point down and manufacturing of the product easier. The results, however, are less effective densifying properties.
Concrete Sealers USA has found a way to use almost the same amount of lithium silicate in their PS104 as they do in their standard densifier. As a result, you can expect close to the similar densifying performance as a straight densifier as well as the added benefit of the siliconate sealer.
How to apply a densifier to a garage floor
The application of a densifier sealer for your garage floor couldn’t be much easier. You first need to make sure your garage floor is clean and free of all dust, oils, and foreign contaminants. Any stains that you have will essentially be locked in unless removed first. The surface must be completely dry before applying the product.
The easiest way to apply the densifier is to use a garden sprayer with a circular spray tip or a microfiber mop out of a paint tray. Work in sections making sure to keep a wet edge at all times. You want to get the concrete wet with product, but not so much that it puddles. If it does puddle, work it into the concrete with a short bristled deck brush or wipe up the excess. If you allow the puddles to dry, you will get a white residue that requires intense scrubbing to remove.
Once applied, you can return the floor to traffic within a couple of hours or so. One application is generally all that is required.
One note to make is that if you plan on adding a topical coating at some point in the future, you will need to grind the concrete in order to remove the sealer and provide a mechanical bond for the coating. Acid etching will not work because the etching solution will not be allowed to penetrate the surface sufficiently in order to react with the concrete.
If you like the look of bare concrete and have a working garage or shop floor that you want to protect without making a big project out of it, then a concrete densifier sealer can be a good solution for you. It’s easy to apply, relatively inexpensive, and will provide years of protection for your concrete.