What is a construction joint? What does construction seam mean

Construction joints: joints left in the sections of each construction unit due to the needs of the construction organization. The construction joint is not a real "joint", it is only because the post-poured concrete exceeds the initial setting time, and there is a joint surface between the concrete poured first, and the joint surface is called the construction joint.

Because the joint surface formed by concrete pouring is prone to various hidden dangers and quality problems, therefore, different structural engineering needs to be cautious in the treatment of construction joints.

Settlement joint: between the various parts of the superstructure, due to the large difference in the number of layers, or the difference in the use of load; Or due to the large difference in the compressibility of the foundation, in a word, when the uneven settlement of the foundation may occur, it is necessary to set up a joint to divide the structure into several parts, so that the settlement of each part is relatively uniform, so as to avoid additional stress in the structure, and the joint is called "settlement joint".

Expansion joint: If the plane size of the building is too long, due to thermal expansion and cold contraction, it may lead to excessive temperature stress in the structure, and it is necessary to set up joints at a certain length of the structure to divide the building into several parts, which is the temperature joint. For different structural systems, the distance between expansion joints is different, and China's current code "Code for Design of Concrete Structures" GB50010-2002 has special provisions for this.

It can be seen that except for the construction joint, the other two joints are real gaps. GB50011-2001 stipulates that for buildings with seismic fortification requirements, the width of settlement joints and expansion joints must meet the requirements of seismic joint width.

The so-called seismic joints are because the plane of the building is irregular, or the vertical direction is irregular, which is not conducive to the seismic resistance of the structure, and the joints divide the structure into several parts.

It is summarized as follows: Construction joint: The joint formed by the construction process is limited by the construction process and interrupted according to the plan, which is called the construction joint. Due to the layered pouring of concrete structures, the gap formed between the concrete in this layer and the previous layer of concrete is the most common construction joint.

So it's not really a sewn, but a face;

Settlement joints: joints set to overcome the uneven settlement of the structure must be completely separated from the foundation to the superstructure;

Expansion joint: a joint set up to overcome excessive temperature stress, and the foundation can be continuously opened;

Seismic joints: joints set up in order to make the building more regular, in order to facilitate the seismic resistance of the structure, the foundation can be continuously opened.

In the seismic fortification area, the settlement joints and expansion joints must meet the requirements of seismic joints.

Construction joint refers to the joint formed between the concrete poured first and later due to the design requirements or construction needs to be poured in sections during the concrete pouring process. The construction joint is not a real "joint", it is only because the concrete is poured first for more than the initial setting time, and there is a joint surface between the concrete poured after the initial setting, and the joint surface is called the construction joint.

Method of retaining construction joints:

The position of the construction joint should be set in the part where the shear force of the structure is small and convenient for construction, and the following provisions should be met: Horizontal joints should be left in columns and walls, and the concrete of beams and slabs should be poured at one time without leaving construction joints.

The construction joint should be left on the top surface of the foundation, below the corbel of the beam or crane beam, above the crane beam, and below the column cap of the beamless floor slab.

For the large-section beam that is connected with the floor slab, the construction joint should be left 20mm 30 mm below the bottom surface of the slab. When there is a beam bracket under the slab, it is left in the lower part of the beam bracket.

For one-way slabs, the construction joints should be left anywhere parallel to the short side of the slab.

The floor slab with the main and secondary beams should be poured along the direction of the secondary beam, and the construction joint should be left in the range of the middle of the secondary beam span 1 3.

The construction joint on the wall should be left in the range of the lintel span 1 3 of the door opening, and can also be left at the junction of the longitudinal and horizontal walls.

The construction joints on the stairs should be left in 1 3 places of the tread board. The concrete of the staircase should be poured continuously. If it is a multi-storey staircase, and the upper floor is a cast-in-place floor slab and has not been poured, the construction joint can be retained; It should be left in the middle of the staircase 1 3 parts, but it should be noted that the joint surface should be diagonally perpendicular to the direction of the stair axis.

The reason for the dispute in the construction is that the old specification stipulates that the staircase construction joint must be left in the middle 1 3 section, and the traditional construction is left in the upper and lower 3 steps, and when it is left in the middle of the staircase, theoretically the shear force is smaller, but the quality of the construction joint is not well controlled during construction, and it is easy to produce the short-term "cantilever" of the poured part when the secondary formwork is supported, which is not conducive to the quality control of the component. ）

The construction joints of the pool wall should be left on the vertical wall 200 mm and 500 mm above the surface of the bottom plate.

For two-way stressed floor slabs, large-volume concrete, arches, shells, silos, equipment foundations, multi-layer rigid frames and other complex structures, the location of construction joints should be set up according to the design requirements.

Prevent the building materials from being extruded and damaged during thermal expansion and cold contraction due to the temperature difference between winter and summer.

Construction joints refer to the joints formed between the concrete poured first and later due to the design requirements or construction needs to be poured in sections during the concrete pouring process.

Construction joints refer to the joints formed between the concrete poured first and later due to the design requirements or construction needs to be poured in sections during the concrete pouring process. The construction joint is not a real "joint", it is only because the concrete is poured first more than the initial setting time, and there is a joint surface between the concrete poured after the first cast, and the joint surface is called the concrete construction joint.

What is a construction joint? How are construction joints formed? What should I do if there are construction joints?

1. What is a construction joint?

The construction joint is when pouring concrete, because of the requirements of the design, or the specific construction, it is poured in different time periods or different locations, and when it is poured successively, a gap will be formed. In fact, this kind of gap is not a gap that really exists, it is just because the first pouring exceeds the initial setting stage, and there will be a joint surface when pouring in the later stage, and this joint surface is called a construction joint.

Second, how to deal with construction joints.

1. When dealing with the construction joint, it should be connected to meet the requirements of the design, but if there is no specific requirement itself, the specification of the reinforcement should be buried at the construction joint, not less than 16 mm. The depth of the embedding and the length of the exposed surface should also meet the requirements, generally not more than 30d of the diameter of the steel bar.

2. The spacing between them should also be set, not more than 20 cm. If you choose a light circle type, hooks should be set at both ends. If a ribbed type is selected, there is no hook.

3. Because of the existence of construction joints, the new and old concrete will be directly exposed to the air, so when it encounters cold air in winter, it needs to be protected from cold and warm. If the concrete does not need to be cured, it will not freeze during the specified curing period, and the concrete can be poured directly. If maintenance is required, the temperature of maintenance should not be lower than 2.

4. If there is loose soil or cement mortar on the surface, choose the method of manual chiseling to ensure that it cannot be lower. If it is mechanically chiseled, it cannot be lower than 10MPa. After the chiseling treatment, it should be rinsed with water, and there should be no problem of water accumulation in the later stage, and then a layer of cement mortar should be brushed in the gaps.

I conclude: The above introduction is what is the construction cost, how the construction cost should be handled correctly, if there is no treatment, there may be water seepage and leakage problems in the later stage.

The construction joint is when the construction personnel pour the concrete, according to the design requirements of the construction drawings, or when the construction is to be poured in sections, and in the middle of the concrete poured before and after pouring, there will be a certain joint, so this joint will be called the construction joint.

The precautions for construction joints are:

1. When pouring, the uniformity and compactness of the concrete as a whole should be controlled within a certain range, and after the concrete is transported to the pouring place, it should be poured immediately, and then put into the mold. And when pouring, if the overall consistency and uniformity of the concrete mixture have changed greatly, it should be disposed of in time at this time.

2. When pouring concrete, it is necessary to avoid the delamination and segregation of the concrete mortar, and the concrete is unloaded through the funnel and hopper when poured, and the height of its own falling cannot be more than two meters. And in the structure of the vertical edge, the height of the concrete can not be more than 3m, otherwise it will have to use a chute or a string barrel to cut the material.

3. Before pouring the concrete with vertical edges, it should be made with 50-100 mm thick cement mortar at the base. In addition, the water-cement ratio and the overall slump of concrete should be raised or decreased according to the pouring height.

4. When pouring concrete, be sure to understand the surrounding brackets and templates, as well as embedded parts and steel bars, as well as the trouser covers in the reserved holes. If there is displacement or deformation, it is necessary to stop the pouring state immediately, and fill them all before the pouring soil solidifies, so that the next step of construction can be carried out.

The role of construction joints

Construction joints can reduce the cracking and deformation of concrete, and improve the stability and safety of buildings. According to the different locations and uses of construction joints, they can be divided into vertical construction joints, Qingchun cavity horizontal construction joints, surface layer joints and joints. The design of construction joints needs to be based on various factors such as building use requirements, structural design and construction technology to ensure that the location and number of construction joints meet the requirements of engineering construction.

Construction joint refers to the concrete cast-in-situ process, because of the construction needs or design requirements, the segmented pouring, the concrete poured successively will form a joint, this joint is called the construction joint.

There are four types of common building construction joints:

1. Settlement joint.

This is a vertical joint set up when building a house, the purpose is to prevent the building from sinking unevenly because of the foundation, thereby causing damage to the house, a kind of settlement joint set up during construction, and the settlement joint is through from the foundation of the whole building to the roof.

2. Expansion joints.

It is a vertical structural joint installed along the length of the house at a suitable part, and the purpose of installation is to prevent cracks in the structure of the building due to changes in temperature, and expansion joints are also called temperature joints.

3. Induce seams.

The cracks caused by the expansion and contraction of the concrete are induced to a fixed position, and the strength of other parts of the structure is weakened through human operation, and the cracks in other parts are reduced.

4. Construction joints.