How water can cause concrete damage?

Concrete water damage is a grave threat but is often overlooked. Water damage to concrete can reduce its lifespan, but you need to first understand how it happens.

1. Chemical attacks

Your concrete can be severely damaged by chemicals such as sulfates or chloride. Exposure to repeated chemicals can cause the concrete to corrode and eventually collapse.

Sulfates

Concrete can be affected by sulfates when they are in solution. They can do this in two ways: chemically or physically. Sulfates can cause chemical reactions in the cement. They weaken the bond between cement paste and aggregate, and lead to cracking.

Sulfate solutions can cause cracking by crystallization or recrystallization of concrete. Both forms are caused by high-sulfate groundwaters and soils as well pollution and seawater.

Chloride

Water, reinforced steel, as well as oxygen, are the three factors that lead to corrosion of reinforced concrete. To prevent deterioration, you can remove any one of these ingredients. That is why dry concrete corrosion is so difficult to find.

However, this is not the case when there are any chloride ions. Chlorides can destabilize the steel bar’s protective layer, which then leads to corrosion. Your concrete could be at risk from chloride exposure and deterioration if you live near the ocean or an area where de-ices its roads.

2. Carbonation

The ideal corrosion protection for steel rebar is provided by fresh concrete, which contains no lime. The problem is that the atmospheric carbon dioxide will eventually create carbonation which turns this free lime into limestone. This can then corrode the steel rebar.

3. Constant Freezing/Thawing

Concrete can crack from constant freeze/thaw cycles. Concrete can crack because frozen water occupies almost 10% more space than liquid. This process is never-ending and cracks can allow for more water seepage into the concrete, causing it to crack further.

4. Alkali Aggregates Reaction (AAR).

Over time, concrete can expand and crack slowly as specific aggregates react with concrete’s acid hydroxides. This is called the alkali-aggregate reactions (AAR).

AARs come in two forms: alkalisilica and alkalicarbonate. ACR is rare because of the difficulty in finding aggregates that are suitable for concrete.

ASR uses silica from the aggregates to react with concrete’s alkalihydroxyxide. The gel forms when concrete absorbs water and expands. Concrete cracks when this gel expands.