How to make a deformation seam in concrete and for what it is needed
The National Encyclopedia of Construction is confident that all bland and competent builders are aware of the ability of concrete coatings to expand at elevated temperatures and humidity, and to shrink, with the fall of these parameters. Therefore, if such structures can not be freely compressed and expanded, the resulting stresses will destroy the structure.
How to make a deformation seam in concrete and for what it is needed.Journalists ProfiDom.com.ua believe that, especially, it is important at the stage of drying the mixture in the first ten days, therefore, we are told that there are deformation seams in concrete floors and similar structures and why they are needed. Also, we will consider the main types of these constructional elements and how they are implemented.
In the organization of monolithic concrete floors, this element of construction is a prerequisite that can withstand such factors as shrinkage and temperature fluctuations. This is especially true for warm floors.
According to building codes, the deformation seam in concrete is obligatory in the following cases:
The area of the tie exceeds 40 m²;
Complex configuration of the floor;
The length of one side of the room is more than 8 m;
On the perimeter of the walls;
Near door openings;
Places of connection of constructions;
High floor temperature.
Analysis of the causes of volumetric deformations shows that structures equipped with seams can counteract such factors as:
Changes in humidity of ambient air;
Chemical reactions occurring in concrete mixtures;
Creep of concrete.
Classification of deformation joints
Deformation seam in concrete
The most commonly used types of deformation sutures are:
Such a division is based on the peculiarities of the application of one or another type, consider each of them in more detail.
The main task of this deformation seam in concrete structures is to exclude the transmission of deformations from the capital architectural elements to the screed of the floor. Main location of insulating joints:
Along the walls;
Around the columns;
Such seams are formed by laying the insulating material along the walls or other structures of the premises before applying the concrete solution.
Solidification of concrete coating in its mass occurs unevenly – the upper layer dries more intensively than the lower one. As a result of this, the level of couplings on the edges is higher than in the center, as builders say – “wrapped up”. As a result of emerging stresses, cracks are formed.
To prevent their appearance and to take this process under control, shrink joints are cut. Typically, they are arranged along the axes of the columns and interconnected with the angles of the same sliced elements that run along the perimeter of the columns. The cutting is made to a depth corresponding to 1/3 of the thickness of the screed, after finishing the coating. This work is carried out using a shredder with an irrigation function.
But, another option is possible – the method of setting the racks of certain sizes at the stage of plasticity of the concrete surface.
This type of delimitation is arranged in places where the next stage of work ends: for example, a day shift for laying concrete. The shape of the end face should be in the form of a “spike-groove” connection, it is possible to apply rails, laid across the longitudinal line, while, on the one hand, they should be treated with bitumen for easy disassembly.
When constructing, it’s important to keep in mind that the deformation structural seam in the concrete also works, and as shrinkage, allowing slight horizontal movements. It is highly desirable to maximize their coincidence and compliance with the design documentation, any changes must be agreed upon.
In premises with increased requirements for water resistance, resin seals are used, since excessive moisture contributes to peeling of coatings. The activation of this process increases with high air temperatures.
Sealing allows to prevent the impact of water and other aggressive substances, as well as clogging of interspace space. When choosing a sealant, the operating conditions and loads subject to concrete coatings must be taken into account.
The main types of sealants that can be used to isolate deformation joints:
Thermoplastics of hot and cold hardening (bitumen, butyl rubber);
Thermoreactoplasts (vinyl acetate, polyurethane, polysulphide);
For example, most floor coverings at industrial plants should be easy to wash and at the same time withstand heavy loads. Sealants for such floors must simultaneously be plastic and firm enough to prevent the formation of chips.