Repaired concrete structures often fail to meet performance expectations, despite advances in repair materials and techniques. Premature failure is a common issue that leads to wasted time and money on repair work. Numerous research studies have been conducted to identify the causes of these failures. Some of the identified causes include incorrect diagnosis of defects, inadequate selection of repair materials, substandard workmanship, and failure to properly remove defected concrete. Addressing these issues is crucial in preventing premature failure of repaired concrete structures.
What are the Causes of Premature Failure of Repaired Concrete Structures?
The cause of damage to a concrete structure is often misdiagnosed or misattributed. One common mistake is the improper selection of repair materials. If repair materials are not carefully chosen to match the properties of the original concrete, it can lead to premature failure of the repaired area. Another factor that can cause failure in repaired concrete is poor workmanship, such as improper placement of repair materials. If the repair materials are not applied correctly, it can result in a subpar repair that is prone to failure.
In addition, proper surface preparation is crucial for ensuring the longevity of concrete repairs. Failure to adequately prepare, remove, and clean deteriorated concrete areas can result in a weak bond between the repair materials and the existing concrete, leading to premature failure of the repair.
Furthermore, damage to concrete structures can occur near the repaired area due to the use of heavy equipment. The operation of heavy machinery close to the repaired concrete can cause unintentional damage, resulting in cracks or other structural issues.
Cutting of steel bars and insufficient splicing of steel reinforcements can also lead to damage in concrete structures. If steel bars are not properly cut or spliced, it can weaken the reinforcement, reducing its effectiveness in supporting the concrete structure.
Insufficient transfer of loads, or inadequate distribution of loads across a structure, can also cause damage to concrete structures. If loads are not transferred properly, it can result in localized areas of high stress or strain, leading to cracking or other forms of damage.
Lastly, poor practices in the placement of repair materials, as well as inappropriate preparation of the concrete base surface, can also contribute to damage in concrete structures. If repair materials are not properly placed or if the concrete base surface is not adequately prepared, it can result in a weak repair that is prone to failure.
Fig. 1: Proper Versus Improper Surface Preparation