Concrete is a hard and strong material and it is used in construction. But it is not invulnerable and can get damaged. There are numerous factors that can lead to concrete degradation and thus need to be repaired over a given period. Knowledge of these problems will assist you in taking better care of your concrete structures. Now, let’s take a look at the various kinds of problems that may cause concrete to need repair.
Types Of Issues That Cause Concrete
Cracking
Defective concrete is one of the most prevalent problems and one of the most frequent is cracking. The various types of cracks are shrinkage cracks, settlement cracks, and structural cracks. Shrinkage cracks appear when the concrete is drying up and thus it is losing some moisture. These are normally minor and do not affect the structure of the building. The settlement cracks are formed when the ground under the concrete has shifted or has settled. Structural cracks are more severe compared to the other types of cracks and affect the overall strength of the concrete. They usually occur due to high loads or improper workmanship.
Spalling
Spalling is the process whereby the outer surface of the concrete starts to chip or flake. This problem is normally attributed to the freeze-thaw cycle whereby water seeps into the concrete, freezes and in the process of freezing it swells and causes the surface to crack. Deicing salts can also be blamed for spalling since they enhance the freeze-thaw effect on the concrete. Spalling not only has an aesthetic impact on the concrete but also leads to the corrosion of the steel reinforcement bar due to exposure to moisture.
Scaling
Spalling is a localized process while scaling is a process that occurs on a larger scale. It entails the removal of the concrete surface by stripping it into thin layers. This is normally occasioned by bad finishing techniques, the use of a lot of water in the mixing process or exposure to unfavorable weather conditions. Scaling reduces the surface hardness of the concrete and thus makes it more vulnerable to further deterioration.
Discoloration
Staining is a problem that can alter the look of concrete. It can stem from many causes such as inadequate mixing, curing problems, or the incorporation of other materials. Discoloration does not normally compromise the concrete in any way but it can be aesthetically displeasing and may be symptomatic of other issues.
Efflorescence
Efflorescence is the white, powdery substance that forms on the surface of concrete. It happens when water penetrates the concrete and dissolves salts and takes them to the surface. When the water dries up, the salt settles at the bottom as deposits. Efflorescence is not detrimental to the concrete but may be considered an issue of appearance. It may also signify that there is some form of dampness problem within the concrete structure.
Corrosion of Reinforcement
In concrete structures, reinforcement bars made of steel are used to increase the load-bearing capacity. But the steel can rust and this is more so if it is exposed to moisture and chlorides. Corrosion of the steel leads to its expansion and the generation of pressure within the concrete which results in cracking and spalling. This problem can significantly weaken the concrete and therefore needs to be addressed as soon as possible.
Alkali-Aggregate Reaction
The AAR is a chemical reaction between the cement paste and certain types of aggregates that are alkaline in nature. This reaction results in the formation of a substance that swells and exerts pressure on the concrete causing it to crack and deteriorate. There are two types of AAR: ASR is the expansion of the alkali-silica gel and ACR is the expansion of the alkali-carbonate gel. Both are known to have a severe effect on concrete structures.
Freeze-Thaw Damage
Freeze-thaw damage is a process in which water within the concrete freezes and expands and thus creates internal pressure. The freeze-thaw process weakens the concrete through cracking, spalling, and other similar processes that affect the concrete. This problem is more apparent in regions where the weather changes from above-freezing to below-freezing.
Chemical Attack
Concrete can be vulnerable to chemical attacks from different agents such as acids, sulfate, and chloride. These chemicals can also get into the concrete and interact with the constituents of the concrete and hence deteriorate. For instance, sulfuric acid can dissolve the calcium hydroxide in concrete to produce gypsum that expands and cracks the concrete. Sulfate attack results in the creation of expansive compounds that destroy the concrete matrix.
Poor Construction Practices
In other cases, the necessity to repair concrete structures is caused by improper work during construction. Some of these are improper mixing, failure to cure the concrete and failure to compact the concrete properly. Lack of quality materials or failure to adhere to the right processes leads to the creation of weak and frail concrete. This means that poor construction practices may cause the early appearance of problems such as cracking, scaling, and spalling.
Environmental Factors
There are several factors that affect the state of concrete and most of them are environmental. The effects of the weather are also severe, for instance, heavy rainfall, high temperatures, or freezing temperatures lead to damage. Also, pollution and the existence of chemicals in the environment can also cause the degradation of concrete at a faster rate.
Load and Stress
Concrete structures are expected to carry certain loads and stresses in structures. Nevertheless, the loads or stress beyond the design capacity are detrimental to the structure. This can range from traffic loads on concrete pavements or other loads on concrete beams and columns. Consequently, the concrete structure is subjected to overloading that may result in cracking, deformation and failure of the concrete structure.
Maintenance and Age
It is important to note that maintenance is very important in the durability of concrete. However, even the most cared concrete will deteriorate with time and show signs of aging. Neglect aggravates the process of wear and tear. Some of the effects include; water seepage, failure to seal the surface, and overlooking small cracks may result in bigger problems. Other factors that may cause concrete repair include; wear and tear that is associated with the aging process.
Conclusion
Various issues can cause concrete to need repair. These include cracking, spalling, scaling, discoloration, efflorescence, and corrosion of reinforcement. Other problems like alkali-aggregate reactions, freeze-thaw damage, chemical attacks, and poor construction practices also contribute. Environmental factors, excessive loads, and lack of maintenance play a role as well. Understanding these issues can help you take preventive measures and address problems early. Regular inspection and maintenance are key to extending the life of your concrete structures. By staying vigilant and proactive, you can ensure that your concrete remains strong and durable for years to come.