Why Does Concrete Crack?

Why Does Concrete Crack?

If you’ve ever walked down a sidewalk or driven on a highway, chances are you’ve seen cracked concrete. It’s an all-too-common sight and one that a variety of factors can cause.

Understanding why concrete cracks are essential for anyone involved in construction, as it can help prevent future problems and ensure that structures are built to last. Concrete cracking is not only an eyesore but can also be a safety hazard. Cracks can result in tripping hazards on sidewalks or cause significant damage to the foundation of a building or bridge. In extreme cases, it can even lead to the collapse of the entire structure. This is why it is crucial to understand how to prevent it.

What Causes Cracks in Concrete?

Before we discuss the different types of cracks in concrete and how to repair them, let’s explore what causes them. There are several reasons why concrete can crack, including the following:

  1. Excessive Moisture: Excessive moisture in concrete can be caused by a variety of factors, such as poor mixing, improper curing, and exposure to rain or other sources of water. When the concrete mixture contains too much water, it can create a weak and porous final product that is more prone to cracking. Additionally, if the concrete is exposed to water before it has fully cured, it can lead to cracking.
  2. Thermal Expansion and Contraction: When concrete is exposed to temperature changes, it expands and contracts in response. This can happen gradually over time or occur rapidly if the temperature changes suddenly.
  3. Poor Mixing: Poor mixing is a common factor that can contribute to concrete cracking. When the concrete mix is not properly proportioned, it can result in a final product that is weak and brittle. This can happen if the mixture contains too much water or if the aggregates are not properly graded.
  4. Heavy Loads: When excessive weight is placed on the surface of the concrete, it can cause the concrete to deform and smash. This is because concrete is strong in compression but weak in tension, meaning that it can handle the weight that pushes down on it, but it cannot handle the weight that pulls or bends it.
  5. Shrinkage: Shrinkage is a natural process that occurs during the drying and curing of concrete, and it is another typical factor that can lead to cracking. As the water evaporates from the concrete, it can cause the material to shrink, which can lead to the development of cracks.

Types of Cracks in Concrete

  • Hairline Cracks: Very thin and shallow, often less than 1/16 of an inch wide. They are usually not a structural concern but can be unsightly.
  • Vertical Cracks: These can occur due to heavy loads or settling and are usually wider at the top and narrower at the bottom.
  • Diagonal Cracks: Can suggest soil movement or settling. They usually start at the corner of a window or door and move diagonally across the wall.
  • Horizontal Cracks: A sign of serious structural issues and can indicate soil movement or water damage.
  • Settlement Cracks: These occur when the foundation sinks, causing the concrete to crack. They usually emerge in the corners of walls or near doors and windows.

How to Repair Cracks in Concrete?

It’s unattractive when this incredibly durable and reliable material falls prey to these unwelcome blemishes (which can appear seemingly out of nowhere, disrupting the smooth and uniform appearance of your concrete surfaces). However, fear not, for there are effective ways to remedy these hideous marks and restore the pristine quality.

The first step in repairing a crack in concrete is to assess the type and severity of the damage. Hairline cracks, while unsightly, are typically not a cause for major concern and can be easily remedied with a concrete crack filler. This specialized product is designed to seep into even the tiniest crevices, filling them up and preventing them from spreading and worsening over time.

For more substantial cracks, a more thorough approach is required. Take, for instance, a crack in a concrete driveway. In this scenario, the damaged area must be meticulously cleaned and cleared of dirt, debris, or loose fragments. This is required to ensure that the repair mix can properly bond to the existing concrete and create a seamless, unbroken surface.

Once the area has been cleaned, a specially formulated concrete repair mix can be applied to the damage. This substance is designed to blend in seamlessly with the surrounding concrete and provide a durable, long-lasting repair. The application process involves cautiously spreading the mix over the crack and using a trowel to smooth it out until it matches the texture and impression of the rest of the concrete.

A more extensive repair may be necessary for more significant cracks, such as those found in walls or floors. In certain circumstances, the damaged concrete section may need to be entirely removed and replaced with new material. Alternatively, an epoxy injection can be used to fill the crack and prevent further harm from occurring. This specialized method involves injecting a resin-based material into the crack, which hardens and forms a strong, stable bond with the existing concrete.

Preventing Concrete Cracks

Prevention is always better than cure, and this is especially true when it comes to concrete cracks. After all, repairing cracks can be time-consuming, expensive, and disruptive, whereas preventing them is a much more straightforward and cost-effective approach.

  1. Mix the Concrete Properly
    Always mix the concrete thoroughly to ensure that the ingredients are evenly distributed. If the mix is too dry, it can lead to shrinkage and cracking. If it’s too wet, it can weaken the concrete and cause it to crack over time.
  2. Pour the Concrete Evenly
    When pouring concrete, ensure that it’s spread evenly and leveled appropriately. Uneven concrete can put stress on certain areas, leading to cracking and other damage.
  3. Allow Proper Drying and Curing Time
    Concrete needs time to dry and cure properly; rushing the process can lead to cracking. Make sure to follow the manufacturer’s instructions for drying and curing times, and avoid walking or driving on the concrete until it’s fully cured.
  4. Avoid Overloading the Concrete
    Heavy loads can put stress on the concrete and cause it to snap. If you’re working on a construction site or using heavy machinery, ensure to distribute the weight evenly and avoid putting too much pressure on any area.
  5. Protect the Concrete From Rapid Temperature Changes
    Concrete can expand and contract with changes in temperature, leading to breaking and other damage. To prevent this, avoid exposing the concrete to rapid temperature changes, such as pouring hot water on it in the winter or blasting it with cold air in the summer.
Learn: how does the concrete mix company help you in construction?

Bottom Line

Concrete cracking is a common problem that can lead to significant safety hazards and costly repairs. Various factors contribute to this, and many different types of cracks can sometimes be serious issues. Repairing cracks in concrete can be done using a concrete crack filler, a specially formulated repair mix, or an epoxy injection, depending on the severity of the damage. However, prevention is always the best course of action, and by ensuring proper mixing, curing, and maintenance, as well as utilizing high-quality concrete and good concrete suppliers, such as Pro-Mix Concrete, we can prevent concrete cracking and ensure that our structures last for years to come.

Remember, the next time you see a cracked sidewalk or damaged concrete structure, it could have been prevented with the right care and materials. Choose Pro-Mix Concrete for your next project, and let us help you build with confidence.