Why AAC Blocks Get Cracks: Causes and Solutions

As a popular building material, Autoclaved Aerated Concrete (AAC) blocks are known for their strength, durability, and thermal insulation properties. However, one common problem that builders and contractors often face when working with AAC blocks is cracking. In this article, we will discuss the reasons why AAC blocks get cracks and explore some potential solutions to this issue.


AAC blocks have become a popular choice for builders and contractors due to their lightweight, easy-to-work-with nature, and energy-efficient properties. However, despite their many benefits, these blocks can still experience cracking. This article will discuss the reasons why AAC blocks can crack and explore some solutions to this problem.

cracked AAC blocks in a residential building

What are AAC blocks?

AAC plant uses cement, lime, sand, water, and an expansion agent are the main ingredients used to make AAC blocks. After the slurry is placed into a mold, it is autoclaved to cure, producing a block that is light, sturdy, and long-lasting. For walls, floors, and roofs, these blocks are frequently employed in building.

Why do AAC blocks crack?

AAC blocks can crack due to several reasons, including:

Thermal expansion and contraction

Thermal expansion and contraction is one frequent reason for AAC block cracking. The blocks may expand or contract in response to high temperatures or temperature variations, which may result in cracking.

Improper curing

AAC blocks require proper curing to ensure their strength and durability. If the blocks are not cured properly, they can become weaker and more prone to cracking.

Structural issues

If the structure of a building is not properly designed or executed, it can cause stress on the AAC blocks, which can lead to cracking.

Improper handling and transportation

If AAC blocks are not handled or transported properly, they can become damaged, which can lead to cracking.

Improper mixing

The AAC blocks could be weak or uneven if the components are not mixed thoroughly. They might be more vulnerable to damage such as cracking as a result.

Incorrect cure

To make sure the blocks are sturdy and long-lasting, they must be thoroughly cured after being produced. They might be weaker and more prone to cracking if they are not properly cured.

Improper storage

It’s important to store AAC blocks carefully to avoid damage like cracking. They might be weakened and more prone to cracking if they are exposed to dampness, severe temperatures, or other harmful conditions while being stored.

Structural stresses

AAC blocks are susceptible to breaking under excessive strain or weight. This may happen if they’re put improperly or if their use is made in a building design that doesn’t adequately take into account their unique properties.

Environmental factors

Environmental factors such as temperature changes, humidity, and exposure to sunlight can cause AAC blocks to expand and contract. Over time, this can cause cracks to form.

By understanding these reasons why AAC blocks may crack, builders and contractors can take steps to prevent these issues and ensure that their constructions are strong and durable.

Solutions to prevent AAC block cracking

Here are some solutions to prevent AAC block cracking:

Proper storage and handling

AAC blocks should be stored in a dry and covered area to prevent moisture absorption. During handling, it is important to use proper lifting and handling techniques to avoid damage.

Careful transportation

During transportation, AAC blocks should be properly secured and protected to prevent damage.

Correct curing procedures

AAC blocks should be cured according to the manufacturer’s instructions. This includes the correct temperature and humidity levels, as well as the appropriate duration of curing.

Proper reinforcement

Reinforcing AAC blocks with steel or other materials can help prevent cracking.

Thermal insulation

Proper thermal insulation can help prevent temperature fluctuations, which can reduce the risk of cracking.

Proper mixing

It’s critical to carefully combine the materials for AAC blocks in order to maintain their strength and longevity. Using the proper proportions of cement, lime, sand, and water as well as the right quantity of an expanding agent are part of this.

Quality control

To guarantee that the AAC blocks satisfy the essential requirements for strength and durability, regular quality control inspections should be carried out.

A suitable installation

To reduce tension on the blocks, which might cause cracking, proper installation procedures should be employed. This entails using the right mortar, maintaining accurate alignment, and refraining from applying too much pressure.

Moisture prevention

Moisture can weaken AAC blocks and make them more prone to cracking. Proper moisture prevention techniques, such as using waterproofing agents and proper drainage, can help prevent this issue.

Proper design

The design of a building should take into account the properties of AAC blocks and ensure that the structure is properly supported and reinforced to prevent cracking.

By implementing these additional solutions, builders and contractors can further reduce the risk of AAC block cracking and ensure that their constructions are strong and durable.


AAC blocks are a popular and versatile building material, but they can be prone to cracking. Understanding the reasons behind cracking and implementing proper storage, handling, transportation, curing, and reinforcement techniques can help prevent this issue. It is also important to choose a block seller who use high-quality AAC block making machines and pays attention to the manufacturing process and quality control of the end products.


Q: Can AAC blocks be used in areas with high moisture levels?

A: Yes, AAC blocks can be used in areas with high moisture levels if they are properly waterproofed and moisture prevention techniques are implemented during construction.

Q: Can AAC block crack during transportation?

A: Yes, AAC blocks can crack during transportation if they are not handled properly. It is important to use proper packaging and handling techniques to prevent damage during transport.

Q: Can AAC blocks be repaired if they crack?

A: Yes, it is possible to repair cracked AAC blocks using specialized repair techniques. However, prevention is always the best approach to ensure the longevity and strength of the construction.

Q: Is it normal for AAC blocks to have small cracks?

A: Small hairline cracks can be normal in AAC blocks and are not necessarily a cause for concern. However, larger, or more significant cracks should be addressed to ensure the structural integrity of the construction.

Q: Can AAC blocks be used in seismic areas?

A: Yes, AAC blocks can be used in seismic areas as long as they are properly reinforced and installed to withstand seismic activity.

Q: Are AAC blocks more prone to cracking than other building materials?

A: AAC blocks are generally less prone to cracking than other building materials, but they can still crack if not handled and installed properly. Proper installation techniques and quality control are key to preventing cracking and ensuring the longevity of the construction.