A concrete structure is prone to many things. If a concrete structure is left exposed to water and unprotected for a long period of time, it can cause the concrete to deteriorate. This happens because of increased humidity and pH level, the creation of space between cement grains, and increased microbial growth. But water is not the only thing that is capable of such devastation. Salt can also damage a concrete structure in many ways and is partially responsible for the water damage. Salt is a natural mineral which means it can appear everywhere including sand and aggregates. This happens mostly when you’re constructing in a seaside setting. It occurs as white lines or powder crystals on the top of the cured concrete. Thankfully there are ways to prevent salt damage to a concrete structure, but first, you have to know how it damages concrete.
How salt damages concrete
Simply put, concrete is an alkaline material formed by a special type of chemical bonding. So any acidic substance or chlorides can break the bond if the concrete is exposed to it for a longer period of time. Salt is sodium chloride and it can damage the concrete in various ways.
Anything with a pH level of less than 7 is considered acidic and can cause serious damage to concrete. Salt is a great catalyst when it comes to lowering the pH level of the concrete. When salt comes in contact with concrete it starts multiple chemical reactions, resulting in lowered pH levels and speeding up in the carbonation process. This affects concrete in different ways. First, it makes the pores in the surface bigger leading to collect more moisture. Second, when moisture gets into the iron structure, the iron in the steel oxidizes to iron oxide or rust causing the iron to expand and concrete to crack.
Ways to prevent salt damage to a concrete structure
So, how do you prevent salt damage to a concrete structure? There are a couple of ways you can prevent salt from affecting the concrete, or at least reduce the damage.
As there are no better ways to tell whether a concrete mixture contains salt or not, the best way to prevent salt damage is to apply a densifier sealer onto the surface of a concrete structure. Any sodium or lithium silicate based densifier will do. You will find plenty of these in the market. Densifier sealers react chemically to create a permanent structure of calcium silicate hydrate (CSH) within the pores. Meaning, this fills up the pores and helps harden the structure. If you already have salt damage, a densifier sealer can help prevent the damage from affecting the structure further.
Water Repellant Sealer
Salt is a hygroscopic substance which means it absorbs moisture from the air. When water gets into concrete it can cause iron to rot or increase the inside pressure of the structure. And the only way to stop this type of damage is to use a water repellent sealer. It forms a hydrophobic barrier causing water and other liquids to skid off the surface. The use of water repellent sealers is common nowadays for their usability and longevity.
In case, if you are unable to find a proper concrete sealant, apply a protective concrete coating. A good quality sealer can significantly help reduce the salt damage, but a coating will stop it. Applying a few coats of plastic paint can do the job for that matter.
Prevention is always better than cure. So always use clean water when mixing the concrete. Then, apply a sealer or protective coating as soon as the concrete is cured. This way you will be able to prevent salt damage to a concrete structure completely.