April 5, 2016 / By Groupa Concrete
You may or may not have noticed some white stains that will form over time on your stamped concrete and ask yourself where it comes from. While this could very well be a problem with the sealer, referred to as sealer diffusion, where the sealer lifts from the concrete, it could also be something else entirely. In this blog we will discuss concrete efflorescence and the factors that cause it.
The term efflorescence can be traced back to 1877 and all reports indicate that there are multiple factors as to why efflorescence occurs, but why does it? Concrete efflorescence happens when moisture and vapours migrate to the surface when exposed to wind and sunlight and carry calcium hydroxide (or lime) with them that then form into salt deposits. The more porous the material, the greater there is a likelihood of concrete efflorescence occurring. There is also a higher risk with greater humidity due to evaporation being slower and allowing a greater span of time for deposits to form on the concrete. The highest chance of concrete having efflorescence occur is also after a rainy winter season. Usually after about three years it should go away but in some extreme cases it will not and it is best to consult a professional on the matter.
For those of us who don’t want to wait out the three-year period until efflorescence diminishes there is hope, especially if it is caught at an early stage. There are multiple ways in which efflorescence can be combated with simple home made solutions. There are many ways to remedy this such as: pressure washing the calcium hydroxide away, or scrubbing and then using a leaf blower to dry the area. For efflorescence that has been sitting around longer and had a chance to mix with carbon dioxide, the use of a mildly acidic solution may work such as vinegar, citric acid, and muriatic acid (muriatic acid should be diluted with water and proper safety measures taken). Once acid washed and lightly scrubbed, you should neutralize the acid with a mixture of baking soda or ammonia and water (9 parts water to 1 part baking soda or ammonia). The solution should then be mopped or sprayed on the surface of the concrete, lightly scrubbed around, and rinsed off the concrete.
As written above, efflorescence is a naturally occurring phenomenon and can be left to its own devices to disappear or taken care of through home remedies or even store bought products. It will appear more so in the spring and is no cause for alarm.