Cracks in basement walls can be caused by design defects or construction defects. Wrong assumptions made during planning can cause this problem.
In general, almost all types of structural elements crack for various reasons. The width of the crack causes problems.
In water storage structures, crack width is limited to 0.2 mm to prevent water movement. In fact, water moves through the 0.2 mm wide slit; However, these cracks are sealed through self-healing.
When surface appearance is important, we limit crack width in water-retaining structures to 0.1 mm. .
Since we are dealing with cracks in the basement wall, the first thing to determine is whether or not the wall is in contact with water. These are usually concrete walls. Therefore, we can assume it is a basement wall containing soil.
In this article, we will first look at concrete basement walls.
Cracks in basement concrete wall
Cracks can be caused by one of the following:
- Design defects
- Thermal Cracks
- Shrinkage Cracks
- Contains cracks
- Inadequate expansion joints
- Lack of movement joints when necessary
Let's discuss each type of crack in detail.
Cracks in basement wall due to construction defects
Cracks can occur in walls due to construction defects. This problem can be caused by a lack of attention to the behavior of the wall or by considering incorrect design parameters.
Some of the most common problems are listed below.
- Lack of attention to lateral limits
If the concrete wall is connected to the foundation, there is a side boundary. With a cantilevered wall, the top of the wall can move freely. However, there is no room for movement in the connection between the wall and the foundation.
This must be taken into account in the design and necessary reinforcement must be provided. Failure to provide adequate reinforcement may occur.
To absorb the lateral tension that arises in the section taking into account the restriction effect, reinforcement in the horizontal direction is necessary.
To achieve this effect, reinforcement in the horizontal direction may be mistakenly forgone.
The article Early thermal cracking More information and calculation procedures can be found in (Calculate R/F requirements).
- Temperature increase during the hydration process
During the hydration process, the temperature of the concrete core increases significantly. This increase in temperature must be controlled.
The various measures that could be taken are discussed in the article Thermal cracking in concrete (a detailed study) could be done to avoid this.
If no model testing is performed, the calculation will be based on the assumed values. Incorrect or unrealistic values taken into account during planning change the required reinforcement cross-section.
Especially when constructing thicker concrete walls, the designer must be aware of the increase in temperature in the concrete wall during the hydration process. Otherwise, thermal cracks in the basement wall and fissures may occur due to the delayed formation of ettringite.
Thermal Cracks in Basement Wall
Concrete is subject to thermal cracking during the curing process and during use.
There are essentially three types of thermal cracks, as described in the article Thermal Cracking in Concrete (a detailed study).
- Freeze/thaw cycles
- Outdoor seasonal temperature fluctuations
- Early thermal contractions
The article mentioned above could provide more information and measures to prevent thermal cracks. Let's look at some examples of thermal cracks in basement walls.
Care must be taken to ensure that cracks are avoided by taking appropriate measures during planning and construction.
Shrinkage Cracks in Basement Wall
The volume of concrete decreases over time and there is a possibility of cracks forming in the concrete.
There are essentially six types of shrinkage observed in concrete.
- Plastic shrinkage
- Chemical shrinkage
- Autogenous shrinkage
- Dry shrinkage
- Thermal shrinkage
- Shrinkage due to carbonation
The article Types of Shrinkage in Concrete (Detailed Study) All types of shrinkage cracks are discussed.
Particular attention must be paid to curing to avoid shrinkage cracks.
Contains cracks
Among the design flaws, we discuss more about containment cracks.
These cracks are solely due to the blocking effect of the wall.
The continuation of the wall must be taken into account in the planning. If the wall is restricted in any direction, this must be taken into account in planning. The following figure shows some limitations that must be taken into consideration to avoid cracks in the basement wall.
Cracks like those in the illustration above occur in basement walls when they are not projecting into the side boundaries created by other elements.
Inadequate expansion joints
Expansion joints are required in other reinforced concrete walls to allow for lateral movement. Lateral movement of the wall may be due to heat exposure, shrinkage, etc.
If there are not enough expansion joints in the wall, cracks can form in the wall.
In a cantilevered wall, vertical cracks appear in the central part of the wall. However, if we provide sufficient horizontal reinforcement, cracking can be minimized.
To avoid cracks in the basement wall due to lateral movements, we provide expansion joints. According to ACI guidelines, expansion joints with distances between 6 and 9 m are permitted.
No movement joints when needed
Movement joints shall be provided at the point where the structural form is changed. For example, for an “L” shaped building, we need to separate two legs, especially the foundation of the building will be a Slab Foundation .
For more information, see the article Types of concrete joints Detailed information can be obtained on this topic.
If there are no joints in the corners, there is a risk of cracks appearing in the wall.
Cracks in basement brick walls
Cracks can occur in the basement wall due to thermal movements and settlement of the foundation.
Let's discuss each type of crack in basement walls
Settling Cracks in Basement Wall
Sinking of a portion of the wall or area of the building may occur due to weak soil conditions or failure of the foundation system.
These cracks form an angle with the horizontal. We can evaluate these types of cracks through a visual inspection.
In particular, concentrated loads on smaller building structures cause cracks of this type.
Cracks in bricks due to lateral loads
If there is lateral loading, there is a possibility of the brick walls cracking.
These cracks could be avoided by lateral limits.
