Reinforced concrete columns can develop various types of cracks such as diagonal cracks, horizontal cracks, splitting cracks, and corrosion cracks. These cracks can be caused by several factors including incorrect design, faulty construction or overloading, corrosion of reinforcement, isolated settlement of foundations, creep and shrinkage.
Cracks in reinforced concrete columns can lead to severe problems such as loss of strength, stability, durability, and aesthetical damage. It is essential to investigate different types of cracks that may occur in columns to implement appropriate measures to restrict them.
Diagonal cracks are one of the types of cracks that can form in reinforced concrete columns. These cracks are caused by shear forces that occur in the column. Horizontal cracks, on the other hand, are typically caused by bending moments that exceed the column’s capacity.
Splitting cracks can develop when the compressive stress on the column exceeds its capacity. Finally, corrosion cracks may form when the reinforcement in the column corrodes over time, leading to a loss of strength and integrity.
Given the severity of the issue, it is crucial to address and prevent cracks in reinforced concrete columns. This requires proper design, construction, and maintenance of the columns, as well as timely repairs when cracks occur. By implementing suitable measures to restrict cracks, we can ensure the longevity and safety of reinforced concrete columns.
Types of Cracks in Concrete Columns
1. Diagonal Cracks
Diagonal cracks that occur in reinforced concrete columns can extend across the entire face of the column at any point along its height. These types of cracks are primarily caused by the columns’ inability to bear the required load, resulting from an inadequate cross-section or insufficient reinforcement steel.
These cracks can significantly affect the structural integrity of the building and need to be addressed promptly. Neglecting them can lead to more severe consequences such as collapse or partial failure of the structure. Therefore, it is crucial to address the root cause of these cracks and ensure that the columns are capable of supporting the necessary load.
Proper measures should be taken to repair the diagonal cracks in the concrete columns. The repair process would involve fixing the inadequate cross-section by either enlarging the column’s size or adding reinforcement steel. It is important to ensure that the repair work is carried out correctly to prevent further damage and to maintain the building’s stability.
In conclusion, diagonal cracks in reinforced concrete columns are a serious issue that should not be ignored. The cause of the cracks should be identified and addressed to prevent any further damage or failure of the structure. Timely repair and maintenance work can help ensure the building’s longevity and safety.
Fig. 1: Diagonal Cracks in Concrete Column
2. Horizontal Cracks
Horizontal cracks in reinforced concrete columns typically originate at the beam-column junction or on the column face where tensile stress is high. Columns that have insufficient moment resistance capacity, inadequate reinforcement, or poorly arranged reinforcement are particularly susceptible to horizontal cracking due to the influence of shear force and direct load and uniaxial bending. Horizontal cracks significantly decrease the shear strength of the column and substantially increase the risk of failure. Therefore, it is essential to address horizontal cracking as soon as possible.
Fig. 2: Horizontal Cracks in Concrete Column
3. Splitting Cracks
Splitting cracks in reinforced concrete columns are a type of crack that appears as short, parallel, vertical cracks with varying widths. These types of cracks usually occur in columns that have low-quality concrete and insufficient steel reinforcement. Splitting cracks are a result of the column reaching its maximum load carrying capacity, which is exceeded when the cross section of the concrete is inadequate or the ratio of reinforcement is insufficient, or a combination of both factors.
The insufficient reinforcement in the column is one of the main causes of splitting cracks. The low-quality concrete used in the construction of the column can also contribute to the formation of these cracks. When the column reaches its maximum load capacity, the splitting cracks appear due to the inability of the structure to handle the load. Therefore, it is essential to ensure that the column is adequately reinforced and that the quality of the concrete is high.
It is important to note that the appearance of splitting cracks is a sign that the column has reached its ultimate load carrying capacity. This capacity can be exceeded when the concrete cross section is not adequate, or the ratio of reinforcement is insufficient. Therefore, it is crucial to conduct proper inspections and testing to ensure that the column is structurally sound and can handle its load-bearing capacity without experiencing splitting cracks.
Fig. 3: Splitting Cracks in Concrete Column
4. Corrosion Cracks
Concrete columns can develop corrosion cracks along the line of reinforcements, which tend to be uniform in width and widen as the column ages. The root causes of such cracks are likely related to reinforcement corrosion and insufficient bond between concrete and steel bars.
If left unaddressed, these types of cracks can lead to a rapid acceleration of reinforcement corrosion, which could further damage the concrete column. It is essential to take action to prevent such corrosion from progressing and causing more significant structural issues.
Fig. 4: Corrosion or Bond Cracks in Concrete Column