Concreting monolithic columns

Modern construction relies heavily on monolithic columns to provide the necessary stability and support for buildings and other structures. In contrast to prefabricated columns, monolithic columns are directly poured and formed on the construction site, guaranteeing a strong and smooth integration with the structure as a whole. This approach is especially useful for intricate architectural designs where strength and accuracy are crucial.

There are several crucial steps in the concreting of monolithic columns, and each one requires painstaking attention to detail. To guarantee that the columns have the appropriate strength and longevity, every step—from assembling the formwork to preparing and pouring the concrete—must be done with precision. In order to prolong the columns’ lifespan and stop cracking, proper curing methods are also crucial.

This post will walk readers through the process of concreting monolithic columns, emphasizing common mistakes to avoid and best practices. Knowing these methods will enable you to complete your construction projects with professionalism, regardless of your experience level. Let’s explore the realm of monolithic columns and learn how to construct sturdy, long-lasting buildings.

Types of concrete columns

The shapes of the structures vary first, i.e., the support’s cross-section. Typically, elements that are square, rectangular, and round are built. Additionally, the columns’ production technologies vary and they can be:

• Prefabricated. Such structures are first manufactured at the factory, and then transported to the construction site. They are distinguished by convenient and quick installation.
• Monolithic. Concrete is poured directly at the construction site, when the solution is poured into prepared forms (formwork) and reinforced with reinforcement.

There are various reasons why the second choice is more preferred. First off, having control over the caliber of the work produced is far more convenient. Secondly, the solution is guaranteed to contain Portland cement of the appropriate grade and not a lower grade. However, there is a significant drawback as well: this type of construction requires more time and work. Monolithic columns will also be far more expensive. In addition, all building stages must be followed, and the temperature regime and concrete mixture introduction technique must be observed.

In order to create solid, continuous structures that are essential for supporting buildings during construction, concrete monolithic columns must be created. To achieve the maximum strength and durability, this process requires careful planning and execution to ensure that the mixture is poured and cured correctly. Builders can make sure their columns are not only structurally sound but also capable of withstanding a variety of environmental stresses over time by knowing the essential procedures and best practices. This tutorial will take you step-by-step through the fundamentals of concreting monolithic columns so that even those who are unfamiliar with this crucial building method can understand it.

Stages of construction of concrete columns

These kinds of structures are built in the order listed below.

Preparation

Prior to beginning work, it is required that:

• Arrange temporary roads and access roads along which construction equipment will move (for such concreting, you need to order a concrete mixer with a crane).
• Provide lighting (part of the work must be done in one go, often during the process night already falls).
• Clean the formwork sheets and lubricate them.
• Prepare the site for installation.

The rules state that if you order a team, three contractors must complete the work:

• 4th category concrete worker (category B1);
• 2nd category concrete worker (categories B1 and B3);
• slinger.

Only if one of the concrete workers is willing to use a crane can the latter be turned down. He needs to have the "crust" of a slinger for this.

Installation of formwork

The frame is typically made of four sides, and the internal dimensions of the frame must match the column’s dimensions. For formwork, moisture-resistant plywood is preferred, but regular boards will work just as well. If finances permit, purchasing prefabricated plastic (for round-section columns), metal (reusable and much simpler to disassemble), or wooden (fit for only rectangular and square columns) boards is more practical. However, small and ornamental structures are the only applications for prefabricated cardboard formwork.

The panels that have been prepared need to be positioned vertically and fastened using screws, wooden spacers, and braces (it is preferable to anchor them, that is, reinforce them with supports in two directions to prevent shifting).

Crucial! If you intend to construct a tall column, only three sides of the formwork will be installed. As the concrete mortar is poured, the fourth section will progressively be constructed.

You can only move on to the next phase after carefully examining the formwork’s strength and geometry.

Reinforcement

These kinds of structures require the installation of reinforced concrete columns, and there are a few crucial guidelines to follow:

• The diameter of the longitudinal reinforcement elements when erecting a prefabricated structure should be at least 16 mm, and for monolithic ones – at least 12 mm. In this case, all rods should be of the same diameter. If different rods are used, then thicker ones should be placed at the corners of the structure.
• It is necessary to calculate the minimum and maximum percentage of reinforcement, that is, the cross-sectional area. The correctness of such calculations will determine what loads the column can withstand. The maximum indicator should not be more than 5% of the cross-sectional area of ​​the structure. It is best to stick to values ​​from 0.4% to 3% (but at the joints it should be doubled).

Practical! For instance, we require the percentage of reinforcement for a column measuring 400 by 400 mm and using 16 mm of reinforcement (four rods are available). The structure’s cross-sectional area, or 40 * 40 = 1600 cm 2, must first be determined. The cross-section is then calculated as follows: 4 * 2.01 = 8.04 cm 2. The percentage of reinforcement, which is 8.04 / (1600/100) = 0.5025%, needs to be obtained.

• The indentation between the longitudinal rods should not be more than 400 mm. If this does not work, then we install thinner ones between the main rods (for example, on 12 mm).
• The size of the transverse rod is determined depending on the diameter of the longitudinal rod and the method of connecting the reinforcing elements (they can be connected by knitting or welding).

• The frequency of clamps depends on the class of the reinforcement (that is, on what is the indicator of temporary resistance to stretching). If the indicator is less than 4000 kgf/cm 2, then the step should be no more than 50 cm. With an indicator of 4500 kgf/cm 2 and above – no more than 40 cm.
• If a monolithic column is built, then the length of the reinforcement should be such that you do not have to make joints. If this cannot be avoided and there is no way to do welding, then the rods join the overlap in the places where the cross section of the column changes. In this case, the size of the overlap should correspond to 30 rod diameters. If the docking without the so -called run over the overlap, then it is better to increase the overlap to 60 diameters.
• You need to pay attention to the protective layer of reinforcement. In the longitudinal rod, it should exceed 20 mm and not be less than the diameter of the reinforcement itself. That is, if the thickness of the rod is 16 mm, then the protective layer will be 16 mm or thicker. Most often, reinforcement with a layer of 3 to 4.5 cm is chosen for columns.

After the column has been strengthened, you can move on to a less complex but still crucial step.

Concreting

Filling the columns with regular concrete is not a good idea when building monolithic foundations. The mobility of the solution should be its primary parameter. For columns, mixtures with a mobility index of P2 are typically utilized. Preference should be given to P4 if the structure is densely reinforced. At the very least, the construction composition brand should be M400. Sand and gravel (or crushed stone) are also needed.

For kneading, there are various component proportions. Usually, the mixture consists of one part PC, four parts gravel, and one part sand.

When concreting, you must adhere to the following guidelines:

• Make sure that the frame does not move. If necessary, it must be adjusted and leveled strictly vertically.
• Bill concrete in the formwork is performed in layers (each layer of about 30-50 cm). The next portion of the mixture can be poured when the previous layer has not yet begun to set. You need to leave a 5-7 cm indent to the top of the formwork. But if the column height is no more than 5 m, then you can fill it in one go.
• During concreting, it is necessary to perform tamping. Hand tampers or special vibrators are suitable for this. Additionally, the formwork must be tapped with a hammer to get rid of air locks.

Crucial! It is required to take 40–120 minute technological breaks if the structure is higher than 5 m. This is necessary for the mixture to shrink.

• Working joints during concreting are usually not needed if the column cross-section is more than 400×400 cm and the height of the building is no more than 5 m. They can also be avoided if, with a cross-section of less than 400×400 cm, intersecting clamps are provided, and the height of the finished element is no more than 2 m. In this case, there is no need to take a technological break for shrinkage.
• Concreting is recommended to be performed at a positive temperature. If the work is carried out in the cold season, it is necessary to use heating cables or cover the future structure with a polyethylene tent.

A vital step in guaranteeing the strength and stability of any structure is the concrete of monolithic columns. It calls for meticulous preparation, exact execution, and close attention to detail. In order to ensure proper compaction and curing, the process entails preparing the formwork, mixing the concrete, and pouring it into the mold. Every step is essential to creating a sturdy and trustworthy column.

Common problems like cracks, weak spots, and uneven surfaces can be avoided during the concreting process by using the proper materials and adhering to best practices. The structural integrity of the columns depends on the concrete mix having the proper proportions and consistency. Additionally, for the concrete to achieve its maximum strength and durability, proper curing is required.

The quality and longevity of construction can be greatly affected by knowing the basics of concreting monolithic columns, whether for residential, commercial, or industrial projects. Building professionals can guarantee that their columns will withstand the test of time and serve as a strong foundation for the entire structure by following recommended guidelines and hiring skilled labor.

In conclusion, it is worthwhile to devote time and energy to mastering and utilizing the best methods for concreting monolithic columns. It adds to the project’s overall success and longevity in addition to improving the construction’s stability and safety. Monolithic columns can be a sturdy and dependable part of any building with the right design, construction, and upkeep.

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