Salt Damage on Colored Concrete

Deicing Salts and Concrete

• Concrete is made of Portland cement, aggregate and water that hardens into a solid surface. Within this surface are small air bubbles. In the winter months, the ice expansion and contraction within the concrete can cause the material to crack and pit. The melted ice and salt migrates into the concrete, increasing the number of freeze-thaw cycles in the material, which seriously undermines the integrity of material. Deicing salts such as rock salt, calcium chloride and magnesium acetate cause the rapid melting that accelerates the contraction process.

Importance of Sealers

• Sealing concrete is one of the best ways to prevent damage from deicing compounds. These sealers help to retard the movement of moisture, but it does not stop it completely. A variety of sealers are available for concrete. These sealers fill concrete pores from the bottom upward. Silane, siloxane and silicone, as well as a number of combinations, are used. Your concrete contractor will advise you on the best type of sealer for your climate region.

Damage on Decorative Concrete

• When deicing salts melt on sealed concrete surfaces, the water and salt mixture, or “brine,” can move under, around and through small areas in the concrete. The sealer is pressured by the constant expansion and contraction of the water, and the top layer eventually will pop off. A combination of sealers may help to prevent or delay this effect. An acrylic sealer is generally applied to decorative concrete and colored concrete to create a membrane that protects the concrete from the top down.

Preventing Deicing Salt Damage on Colored Concrete

• Periodic re-sealing of the concrete may be necessary if you live in an area with severe winters and regularly use deicing salts on concrete surfaces. Expect to re-seal the concrete every three years, according to the AbstractConcrete website. If salts have damaged the colored concrete surface, you may need to use a colored finish to recolor the area to match the rest of the surface. Stripping the old sealer before re-sealing may be necessary. Consult with your concrete professional for advice on treating stains and color fading in your decorative concrete surface.