White spots on my concrete garage floor that have a jelly substance in the center of them

Here’s a great piece of advice I saw in the The Signal of Santa Clarita Valley about concrete floors:
My home is about 10 years old. I noticed some white spots on my concrete garage floor that have a jelly substance in the center of them. Do you know what it is?
Steve P.

Hi Steve,
This is reactive aggregate. It is a chemical reaction between the cement and the type of rock that was used in the concrete mix. What you’re seeing in the center of the spots is an alkali-silica gel that can expand with moisture and cause cracks in the cement of the concrete.
Depending on the amount of reactive aggregate that was used in the mix and how close to the surface it is, it could take years before seeing any signs of damage. There are ways to neutralize the reaction which may prevent further damages.
First, you would want to sand each spot and remove as much of the gel as you can. Then you would apply an acid solution of 20 percent muriatic acid and 80 percent water. You could mix it up in a spray bottle and let it set for 3-5 minutes. With this I would recommend using a respirator, gloves, long sleeves and ventilation. Be extremely careful when working with acid. It will damage your skin and lungs. Next, you would want to neutralize by cleaning the spot with a 10 percent ammonia and 90 percent water solution. Clean the spot and allow to dry. Finally, brush apply lithium silicate to the spot. Allow to soak in and dry. Then you would reapply the finish you had, if any or leave as is but these areas will show some discoloration.
Again, depending on the amount of reactive aggregate in that concrete, this procedure may prevent further damages. If left unchecked, moisture could cause expansion and cracking of the slab.

Read full article…