ELAZIG GUNISIGI NEWSPAPER - May 2010
THE IMPORTANCE OF CONCRETE CURING IN CONSTRUCTION QUALITY
There are significant deficiencies in building supervision in our country. A building inspection system that should be applied during the construction of buildings has not yet been established nationwide. The vast majority of the buildings constructed in Turkey are residential buildings. In nearly all of the past devastating earthquakes, almost all of the deaths occurred in residential buildings. Therefore, especially for residential buildings, the implementation of building supervision is crucial. In our province, this task is carried out by the municipality. The supervision of both reinforcement and concrete plays a vital role in ensuring the construction of buildings that meet standards and have high earthquake performance. In this article, I would like to bring attention to an issue that is rarely included in inspections across Turkey: "Concrete Curing."
The first step in construction quality is the project. The project prepared for the building must comply with the earthquake regulations and relevant standards. The second step is to implement the project as it is, without making any changes. This means strictly adhering to the dimensions, locations of structural elements, and material quality. The placement of reinforcement and concrete pouring are particularly important. Even if great care is taken in all of these, it cannot be said that the necessary work has been completed. The curing of concrete, or the process of keeping it moist, is an absolutely critical parameter that cannot be overlooked.
When concrete is initially mixed, a chemical reaction occurs between the cement and water. As a result of this reaction, heat is released, and the concrete loses water. It is inevitable that concrete will lose water, and if its temperature is not controlled, the desired strength cannot be achieved. This is what is referred to as "burning" or damaging the concrete.
During concrete pouring, at least three samples are taken from the concrete. These samples are kept in curing tanks (water tanks) with a constant water temperature of 23°C for 28 days. After 28 days, the concrete's class is determined through compression testing. For concrete to reach the desired strength, it must be kept moist for 28 days.
While the samples are being cured in the tank, is the concrete in the actual building being moistened? Is the strength of the concrete in the building the same as that of the samples? If the building is not being cured in the correct way and for the proper duration, the strength of the actual building’s concrete will differ from that of the sample. In other words, the samples will not represent the real situation.
Buildings behave according to their construction characteristics, not according to their project specifications, under earthquake forces. Every element of the rough construction must be moistened for the required period. If this rule is not followed, there will definitely be a difference between the project’s concrete strength and the actual concrete strength. No matter how good the concrete mix and material (cement, gravel, and sand) are, or how closely the pouring rules are followed, it is impossible to reach the project strength unless the concrete is properly moistened. The curing process is as crucial to concrete strength as the other rules for preparation and placement.
After concrete has set, it must be continuously moistened without interrupting the construction work. If concrete samples are kept constantly submerged in water, the concrete in the building must also be continuously moistened. Ensuring this is largely the responsibility of local authorities. For local governments, adding concrete curing to the list of building inspection requirements is a challenging but necessary task. This issue will be addressed in more detail in another article.
The purpose of this article is not only to emphasize the importance of concrete curing as a requirement in building supervision but also to inform our citizens on this issue. Knowledgeable eyes in this regard will act as social inspectors of construction. While buildings are being constructed, the social pressure from the conscious neighbors will ensure that the concrete is properly cured.
To reduce the effects of earthquakes, every citizen has a role to play. You can be voluntary construction inspectors of your cooperative's construction, TOKİ projects, and basically every construction project around you. Those who do not apply concrete curing or claim it is unnecessary, I must point out their technical inadequacies. To conclude with a final sentence, "A drop of water for concrete can save lives in an earthquake."