Masonry buildings can suffer from a range of cracks in different areas, such as walls, foundations, slabs, and columns. These cracks can stem from various causes, and repairing them requires specific methods. Unfortunately, some issues in structures can arise abruptly, without any warning. For instance, cracks or foundation settlement can appear without prior notice. Often, these problems result from poor construction practices or negligence during the initial building phase. Therefore, taking care during the early stages of construction can prevent such issues that demand significant maintenance.
Causes and Types of Cracks in Masonry Buildings and their Repair Methods
Cracks in masonry structures can appear at certain periods of time, and there are several common causes for these cracks. Understanding these causes and taking precautions can help prevent them from occurring.
One common cause of masonry cracks is settling. Over time, the foundation of a building may settle or shift, causing stress on the masonry structure. This can lead to cracks, particularly near corners or windows. To prevent settling-related cracks, it’s important to have a strong foundation and properly compacted soil beneath the structure.
Another cause of masonry cracks is moisture. When water seeps into the masonry, it can cause the material to expand and contract, leading to cracks. This can be prevented by properly sealing the masonry and ensuring proper drainage around the building.
Temperature changes can also cause masonry cracks. As temperatures rise and fall, masonry materials can expand and contract, causing stress on the structure. Properly designed expansion joints can help mitigate this issue.
Finally, external factors such as earthquakes or nearby construction can cause masonry cracks. While these factors may be out of one’s control, taking precautions such as reinforcing the structure can help prevent severe damage.
In summary, understanding the common causes of masonry cracks and taking necessary precautions such as a strong foundation, proper sealing and drainage, and properly designed expansion joints, can help prevent these cracks from occurring and ensure the long-term stability of the structure.
Cracks in Brick Mortar Joints
Vertical or horizontal cracks can often be observed at the mortar joints of brick walls, typically appearing about 2 to 3 years after construction. One of the primary reasons for these cracks is sulfate attack, which can weaken the mortar over time. To prevent this issue, it is crucial to take certain precautions during construction.
One important step is to check the sulfate content of the bricks being used. If the bricks have a high sulfate content, they are more likely to cause sulfate attack on the mortar. Therefore, it is essential to use bricks with low sulfate content to avoid this issue.
Another factor that can contribute to sulfate attack is dampness in the brick wall. Damp walls are more susceptible to sulfate attack, so it is essential to avoid any conditions that may cause dampness. This can include ensuring proper ventilation and preventing water from seeping into the wall.
Overall, by taking measures to control the sulfate content of the bricks and avoid dampness in the brick wall, it is possible to prevent vertical or horizontal cracks from appearing at the mortar joints of brick walls.
Crack Formation Below the Load Bearing Walls
Cracks have been identified beneath load-bearing walls, specifically those that support reinforced concrete slabs. The primary cause of these cracks is the expansion or contraction of the slab due to temperature changes, which occurs horizontally. These cracks are most evident on the topmost story of the building, which is more exposed to temperature variations. Furthermore, the lack of a smooth contact point between the wall and the slab results in the development of frictional forces at the point of contact, leading to wall cracking.
To prevent such cracking from occurring, it is recommended to apply a bearing plaster over the brick wall. This plaster will provide a smooth contact surface for the floor above it, which can reduce the amount of friction between the wall and the slab. Additionally, a bituminous coating can be applied over the plaster if needed, further enhancing the contact between the wall and the slab. By taking these precautions, the likelihood of cracks developing in the walls due to slab expansion or contraction can be significantly reduced.
Main Wall and Cross Walls Joint Cracks
Improper bonding between the cross wall and the main wall can lead to the formation of cracks between the joints. Therefore, it is important to ensure that there is a proper and high-quality bonding between the two walls to prevent this from happening. One effective way to achieve this is through a process called toothing.
Toothing involves creating a series of interlocking teeth along the edges of the two walls, which helps to create a stronger and more secure bond between them. The teeth are created by cutting small, angled grooves into the edges of the walls, which fit together like puzzle pieces when the walls are joined.
By using toothing to bond the cross wall and the main wall, the risk of cracks and other types of damage is significantly reduced. This is because the interlocking teeth help to distribute any stress or pressure more evenly between the two walls, making them more resistant to movement and other types of strain.
Overall, it is crucial to ensure that there is a proper and high-quality bonding between the cross wall and the main wall to prevent cracks and other types of damage from occurring. Toothing is an effective method for achieving this, and can help to create a stronger and more secure bond between the two walls.
Cracks Found in R.C.C Columns and Masonry
Temperature variation is a leading cause of cracks in buildings. These cracks are often a result of differential movement between the masonry and columns. Depending on the temperature, this movement can be due to either expansion or contraction. To conceal these cracks, grooves can be made in the reinforced concrete column and masonry junction. Additionally, placing chicken wire at the plaster junction between the columns and masonry can help alleviate the impact of temperature variation.
The Horizontal cracks between R.C.C slab and the brick parapet
The non-projecting slab is prone to cracking, which is mainly caused by temperature changes and drying shrinkage. Microscopic cracks can form and then spread as the slab expands or contracts. To conceal these cracks, a groove can be made at the junction of the masonry. Another way to hide the cracks is to provide chicken wire alternately at the plaster junction. These measures can be effective in concealing the cracks and improving the appearance of the slab.
Cracks in Roof Slab
Roof slabs are prone to developing cracks when exposed to extreme temperature variations. This can be a common problem that can cause significant damage to the structure of the building. To prevent this issue, it is recommended to provide a weatherproof course on the roof. This can help to minimize the impact of temperature changes on the roof and prevent the formation of cracks.
Thankfully, there are new treatment methods and compounds available that can be used as a weather course. These compounds are specifically designed to be applied over the terrace, and they provide an additional layer of protection against weather damage. By using these compounds, property owners can reduce the risk of cracks forming on their roof slabs and extend the life of their building’s structure.
Overall, it is crucial to take measures to protect your roof from temperature variations and weather damage. By investing in a weatherproof course and using the latest compounds, property owners can significantly reduce the risk of damage to their roof and ensure that their building remains structurally sound for years to come.
Repair Methods for Cracks in Masonry Building Structural Members
When cracks appear in main structural members that cannot be compromised, certain measures need to be taken. Grouting or uniting is a common solution, which involves the application of either cement or epoxy mixture. Epoxy has the advantage of being able to fill even small and thin cracks, as fine as 0.1mm. Furthermore, epoxy gains high strength and adhesion, making it an effective solution for structural cracks.
For cracks appearing on non-structural members, a flexible sealant can be used. This helps to control differential movement, such as expansion or contraction, of the member under temperature changes. This type of solution is effective for ensuring that cracks do not worsen over time and provides added stability to the member.
When cracks appear in plain cement concrete, there are various options for filling them. Epoxy putty, polymer filler, or lime cement mortar can all be used to address cracks in cement. These solutions provide a stable and long-lasting fix, ensuring that the integrity of the structure is not compromised. It is important to address cracks in cement as soon as possible, to prevent further damage or the need for more extensive repairs down the line.
Measures for Foundation Settlement
Unequal settlement of a building’s foundation can occur due to variations in the bearing capacity of the soil at different points. This can result in the formation of cracks in the building, which can compromise its structural integrity. To prevent this from happening, certain preventive measures need to be taken.
One such measure is to plan the foundation to be laid on hard soil. This ensures that the foundation has a stable base and can withstand the weight of the building without settling unevenly. Additionally, gradual raising of the foundation and walls can be done, which allows the structure to have an allowable settlement. This means that the settlement value should not go beyond what is considered acceptable, even under any combination of loads.
Furthermore, it is important to design the foundation in a way that facilitates uniformly distributed pressure on the soil. This helps to ensure that the weight of the building is evenly distributed, reducing the risk of uneven settlement and cracking. By taking these preventive measures, the risk of structural damage to the building can be minimized, and its longevity and safety can be ensured.
Plinth Protection
To prevent the issue of unequal settlement of plinth, which can arise due to expansive soils like black soils (also known as black cotton soil) near the plinth, certain measures can be taken. One such approach is to remove the expansive soils from the vicinity of the plinth. This can be achieved by creating a barrier using sand harries. Additionally, the construction of drains and flagging concrete can be employed to divert rainwater away from the plinth, thereby mitigating the risk of water-induced settlement. Another factor to consider is the penetration of roots into the plinth, which can be detrimental. To prevent this, it is crucial to avoid planting trees with lateral growing roots in close proximity to the plinth during construction. By implementing these preventive measures, the issue of unequal settlement of plinth can be effectively addressed, ensuring the stability and durability of the structure.