Understanding the Types of Cracks in Concrete

Types of Cracks in Concrete

Concrete is one of the most commonly used building materials in the world, used for everything from sidewalks and driveways to high-rise buildings and bridges. However, like any other material, concrete is not immune to cracks. In fact, cracking is an inevitable characteristic of concrete structures, and it can occur due to a variety of reasons and they can have different degrees of severity.

Here are the different types of cracks in concrete :

a) Non-Structural Cracks

These are the cracks that do not pose any threat to the integrity of the concrete structure. They are usually hairline cracks, and they are primarily caused by the natural drying process of concrete, temperature changes, or minor stress. However, these types of cracks do require repair not primarily because of their performance but because of the overall performance of the concrete structure.

b) Structural cracks

Structural cracks are more severe and require immediate attention. These cracks can compromise the integrity of the concrete structure and may lead to the collapse of the structure if not addressed promptly. There are seven main types of structural cracks in concrete, which we will discuss in detail.

1) Plastic Shrinkage Cracks

These types of cracks are caused by rapid drying of the surface of the concrete before it has had a chance to properly cure. This can occur due to hot and dry weather or a lack of moisture in the concrete mix. These cracks happen when the surface of the concrete dries out too quickly, leaving behind a patchwork of shallow, random cracks. The result is a series of shallow, random cracks that can affect the appearance and durability of the concrete.

2) Crazing and Crusting of Concrete

a) Crazing

Crazing cracks are like a web of fine, shallow cracks on the surface of the concrete. They are caused by the rapid evaporation of moisture from the surface of the concrete during the early stages of curing. This can be caused by a variety of factors, including high temperatures, low humidity, and exposure to wind or direct sunlight. The crazing of concrete is often considered a cosmetic issue and doesn't typically affect the structural integrity of the concrete.

b) Crusting

Crusting cracks, on the other hand, are deeper and wider than crazing cracks and occur during the later stages of concrete curing. They form when the surface of the concrete dries out too quickly, forming a hard crust that traps moisture inside the concrete. This moisture then tries to escape, causing the surface of the concrete to crack. Crusting cracks can be caused by overworking the concrete, not properly curing it, or using too much water in the mix.

3) Settling Cracks

Settling cracks occur when the soil beneath the concrete moves or shifts, causing the concrete to settle and crack. Inadequate soil preparation and soil erosion are common causes of settling cracks. These types of cracks can create unevenness and tripping hazards, as well as lead to other types of cracks. Proper soil preparation, drainage, and installation techniques can help prevent settling cracks from forming.

4) Expansion cracks

Expansion cracks occur when the concrete expands and contracts due to changes in temperature and moisture levels. These types of cracks often appear as a straight line, running across the surface of the concrete. Expansion cracks can be caused by a variety of factors, including extreme weather conditions and improper joint placement. Cracks are caused due to changes in temperature and are generally referred to as thermal cracks. While not typically a structural concern, expansion cracks can allow water to seep into the concrete, which can lead to other types of cracks and damage. Proper installation techniques and the use of expansion joints can help to prevent expansion cracks from forming. .

5) Heaving cracks

Heaving cracks occur when the ground beneath the concrete swells or shifts, causing the concrete to heave upward. This type of cracking is often caused by extreme temperature changes, moisture changes, or freeze-thaw cycles. Heaving cracks can cause significant damage to the concrete, as well as surrounding structures like walls or foundations. Proper drainage, soil compaction, and installation techniques can help to prevent heaving cracks from forming. If heaving cracks are already present, it's important to address the underlying cause to prevent further damage.

6) Overloading cracks

Overloading cracks occur when the weight placed on the concrete exceeds its capacity to support it. This can be caused by heavy machinery or vehicles, or even excessive foot traffic. Overloading cracks can be particularly dangerous, as they can compromise the structural integrity of the concrete and surrounding structures. Proper weight distribution, reinforcement, and maintenance can help to prevent overloading cracks from forming. If overloading cracks are present, it's important to address the issue promptly to prevent further damage and use a more durable concrete to ensure safety.

7) Corrosion of reinforcement

Corrosion of reinforcement occurs when the steel reinforcement inside the concrete begins to rust, causing it to expand and crack the concrete. This type of cracking is often caused by exposure to moisture, salt, or other corrosive materials. Corrosion of reinforcement can be a serious issue, as it can compromise the structural integrity of the concrete and surrounding structures. Proper concrete mix design, placement, and maintenance can help to prevent corrosion of reinforcement from occurring. If corrosion of reinforcement is present, it's important to address the issue promptly to prevent further damage and ensure safety.

Also Read : How to Do Curing of Concrete & Different Curing Methods