Seven Ways Concrete Can Fail

by TRP Ready Mix on November 28, 2022

And How to Avoid It

The average winter in Ottawa can hit low temperatures of -20C° or lower. If your concrete isn’t made properly, the frost can expand and crack the foundation and walls.

If you’re a contractor, you know that concrete is a vital part of any construction project. But did you know that there are things you can do to avoid concrete failure?

We’ll discuss some of the most common causes of concrete failure, and we’ll provide tips on how to prevent them.

We hope this information will help you deliver high-quality projects that stand the test of time.

1. Corrosion of Steel Reinforcement & Carbonation

Two of the most common types of failure are corrosion of steel reinforcement and carbonation. Corrosion of steel reinforcement is caused by exposure to oxygen and moisture. The steel begins to rust, which weakens the concrete and can eventually cause it to crumble.

Carbonation occurs when carbon dioxide from the air reacts with the calcium hydroxide in the concrete. This reaction creates calcium carbonate, which is much weaker than concrete.

How to Avoid It

Fortunately, there are several ways to prevent or mitigate these types of failures.

Proper design and construction, including adequate cover for steel reinforcement and appropriate curing of concrete, can help to reduce the risk of corrosion and carbonation.

In addition, regular maintenance and repair can prolong the life of concrete structures and help to prevent costly failures.

2. Sulfate Attack

This occurs when sulfates in the soil or groundwater come into contact with the concrete, causing it to expand and crack. A sulfate attack can also lead to the formation of efflorescence, a white powdery substance that forms on the surface of the concrete.

In severe cases, sulfate attacks can cause the concrete to crumble and collapse. While sulfate attack is a natural process, it can be accelerated by exposure to salt water or industrial pollution.

How to Avoid It

There are several ways to prevent sulfate attack, including the use of sulfur-resistant concrete and the installation of a barrier between the concrete and the source of sulfates. In addition, regular monitoring and repair can help to identify problems early and prevent major damage.

3. Poor Finishing

One way that concrete can fail is through poor finishing. This happens when there is trapped air in the concrete, which can cause issues like uneven curing, shrunken concrete, and a decrease in strength.

How to Avoid It

There are a few ways to avoid this, such as using a vibrating tool to remove air pockets and ensuring that the concrete is properly mixed. Finishing also plays a role in the aesthetic of the concrete, so it’s important to get it right if you’re going for a particular look.

4. Freeze-Thaw Deterioration

Another common form of failure is known as freeze-thaw deterioration.

This occurs when water seeps into the concrete and then freezes, expanding and breaking the concrete. Freeze-thaw deterioration can be particularly damaging in areas that experience repeated freezing and thawing, such as in cold climates or near bodies of water.

Left unchecked, freeze-thaw deterioration can cause:

• Cracks
• Pitting
• Flaking

In extreme cases, the concrete may even crumble and collapse.

How to Avoid It

Fortunately, there are several ways to prevent or repair freeze-thaw damage. For example, using air-entrained concrete can help to reduce the effects of freeze-thaw cycles, and sealants can be used to fill cracks and protect exposed concrete from further damage.

5. Alkali-Silica Reaction

Alkali-silica reaction (ASR) is a chemical reaction that occurs between the alkalis in concrete and the silica in aggregates or other reactive materials.

ASR can lead to the expansion and cracking of the concrete, and can ultimately cause concrete to fail. ASR is often difficult to diagnose, as it can take years for the symptoms to manifest.

However, there are some telltale signs that ASR may be present, including surface discoloration and spalling (flaking or peeling) of the concrete. If left unaddressed, ASR can cause significant damage to concrete structures.

How to Avoid It

First, you can use low-alkali cement or an air-entraining admixture. You can also use a water-reducing admixture. This will help to control the expansion.

Additionally, you can use a calcium carbide residue or fly ash in your concrete mix to neutralize the alkalis. Finally, you can seal the concrete with a silicone or acrylic sealer. This will help to prevent moisture from entering the concrete and causing ASR.

6. Overloading Concrete

When concrete is placed under too much stress, it can crack, crumble, and collapse. This can be caused by putting too much weight on a concrete structure, or by subjecting it to extreme temperatures.

How to Avoid It

Often, overloading concrete can be prevented by reinforcing the material with steel rods or cables. However, even the strongest reinforcement cannot always withstand the forces of nature. As a result, overloading remains one of the most common causes of concrete failure.

7. Using Improper Raw Materials

Incorrect raw materials are one of the most common ways that concrete can fail. If the wrong type or amount of aggregates, cement, or water is used, the concrete won’t be strong enough to support the weight it needs to.

Sometimes, using too much of a certain raw material can be just as bad as not using enough. For example, using too much water can make the concrete more susceptible to freeze-thaw damage.

It’s important to get the proportions right when making concrete so that it will be durable and long-lasting.

How to Avoid It

There are a few different types of raw materials to pour concrete. The most common type of aggregate is gravel, which is made up of small rocks and stones. Another popular choice is sand, which is a finer material that can help to fill in any spaces between the gravel pieces.

Finally, cement is the binding agent that helps hold everything together. To achieve the desired strength and consistency, the proportions of these ingredients must be carefully measured.

Alternatively, you can use ready-mixed concrete to avoid having to measure and mix the raw materials yourself. This can be a convenient option, but it’s important to make sure that the concrete is of high quality and that the proportions are still accurate.

Takeaway

Concrete is one of the most popular building materials in the world, but it can also be one of the most troublesome. If concrete is not made or used properly, it can fail in several ways. By understanding the seven most common ways that concrete can fail, you can help to prevent problems before they start.

If you are looking for concrete services or ready-mixed concrete? Get a quote today!