First, the main reason for cracking gypsum board joints
1, the gypsum board volume stability characteristics
General decoration materials are afraid of water, there is the phenomenon of swelling and shrinking, but the gypsum board can be said to be a good performance material in various types of building decoration. This is because industrially used gypsum is formed by heating dihydrate gypsum and discharging crystal water. The gypsum board is shaped and shaped, and water is added to the burned and ground hemihydrate gypsum to again form the important characteristics of the dihydrate gypsum structure. It separates from the gypsum slurry in the form of pin felt-like crystals. During the drying process, micropores are formed and the gypsum building material has a “gypsum respiration†characteristic, that is, when the humidity of the air changes, it can absorb moisture, and it can quickly Emit to go.
The linear expansion and shrinkage of the gypsum board in the air-dry state is negligible. Even if the air humidity reaches 90%, the maximum stretch rate of the gypsum board is only 0.015% in 24 hours. Therefore, this tiny amount of expansion and contraction is not caused by the board. The main cause of surface deformation and cracking of joints.
2. The effect of the strength of the paper plasterboard on the deformation
The structure of the gypsum plaster board is a plate that is tightly bonded together by the gypsum core and the facing paper. The cover paper plays a role in resisting tension and reinforcement, and the cover paper layer has a great influence on the quality of the board. The plate is not useable. The strength and elasticity of the two-dimensional fibers in the cross-machine direction are different, the longitudinal direction is larger than the transverse direction, and the longitudinal bending and deformation resistance are also stronger.
Gypsum board has strong moisture resistance. The paper surface can prolong the time for the board to take in water, but it cannot prevent water absorption. During installation and construction, for a long time or continuous wet soaking, the strength of the paper plaster will decrease. Therefore, wet sheets must not be constructed and installed. However, when the damp plate is ventilated and dried, its strength and deformation resistance can still be restored.
High temperature has a certain influence on the strength of the gypsum board. When the environmental temperature of the gypsum reaches 42°C, the solidified gypsum starts to change the crystal structure and the strength is impaired, so that the gypsum plaster board cannot be directly connected to the heater or the like.
3, the design and construction of light steel keel skeleton structure
The rational design of the skeleton, the use of qualified materials and parts, and the strict control of construction quality are important guarantees for ensuring that the wall and ceiling of the QST system are not deformed or cracked. Errors and omissions in any one of these links can lead to distortion and cracking. For example, the fixation between the gypsum board and the keel, if not in order or fixed, will cause the board to generate internal forces, and the board seams will be sheared, which will cause deformation and cracks; the stiffness and straightness of the light steel keel is not enough, and the spacing is not proper. , will certainly produce deformation cracking.
4. Caulking process is a direct factor in the success or failure of joint processing
Building partitions and suspended ceilings are in a variety of stress states. Therefore, the vertical and horizontal joints of the gypsum plasterboard are subject to a variety of stresses. This requires that the panels should be properly left and the caulking materials themselves have sufficient strength. And cohesion, but also have a reasonable joint construction process and high operating skills, in order to balance the tensile stress, to avoid cracks. At present, there is no clear regulation on the material design for caulking, and most of the construction units randomly choose caulking putty, whose strength can not meet the requirements; some construction units use high-grade plastic materials, but the price is expensive; some construction units use perforated paper tape to strengthen, Or with grid reinforcement, construction processes are also different, construction season and the environment is different. Therefore, how to grasp the caulking process is very important.
5, the impact of non-orderly and uncivilized construction
After the completion of the caulking process, even after the wallpaper paint is applied, the installation work of the water, electricity, and wind on the ceiling in the wall has not been completed, and the installer will step on the skeleton of the dragon or skid the fixed panel. Cracks in the seams even deform the board surface. Some ceiling design is not on the people, some operators also stepped on the sub-keel, so that the deformation of the skeleton deformation, this situation is especially common in the rush schedule project, we must strengthen management to be overcome.
Second, to avoid distortion and crack design points
1. Reasonable selection of light steel keel and accessories
The skeleton of the partition wall is made of light steel keel. Its strength, stiffness and flatness are indicators of the quality of the skeleton. If the straightness of the keel is not good, the skeleton will not be smooth. After the gypsum board is installed on the keel, internal stress will be generated, and the internal stress will inevitably lead to cracking at the seam of the board during the release process. Therefore, while designing the primary and secondary keel specifications, the design shall also require the stiffness and straightness of the drawings in accordance with national standards. Do not ignore the primary and secondary keel suspensions, connectors, and extensions. Choose a reliable specification. Ensure that the installed skeleton is in an unstressed state and effectively avoid cracking of the gypsum board joints.
2, the choice of gypsum board
There are three types of plain gypsum board, waterproof type and fireproof type. The design can be selected according to different usage requirements, different regions and construction seasons. The partition wall is generally 12 thick. The spacing between the ceiling keel and the thickness of the gypsum board is related. The ceiling is 12 thick. If the thickness is 9.5, the spacing between the keel should be reduced. When there is a high requirement for moisture resistance, such as spraying on the surface of the board, a waterproof layer should be added on the surface of the board, a layer of water-resistant putty or a colorless waterproof agent can be scraped.
Gypsum plasterboard is a covering material for partition walls. It is tightly fixed with high-strength self-tapping screws and light steel keels. If the gypsum board and keel can not be firmly fixed, the gypsum board joints when external forces act. There will be shear forces at the place, leading to cracks in the board seams, so the strength of the gypsum board and the quality of the edge formation are important factors.
The National Cultural Palace selected the dragon brand gypsum board, which has the characteristics of high strength, good toughness, uniform foaming, and full molding at the edges.
3, caulking material
Caulking materials include seam strips and caulking putties. The seams have a good self-adhesive ability and strength and act as stiffeners at the board seams. Caulking putty should not only have good strength and adhesion, but also have certain toughness and good construction performance. If you do not meet the above requirements, cracks will inevitably occur.
Third, to avoid deformation and cracks construction points
1, the construction environment
Do not put gypsum boards in a damp, ventilated place during construction. Do not install paper plasterboard until the relevant wet job is completed.
2, install light steel dragon skeleton
The construction must be carried out strictly according to the drawings and specifications, and the spacing between the keel and the hanging bars must not be arbitrarily increased. The installed skeleton must be in an unstressed state (except for the influence of its own weight ). After the construction is completed, an intermediate acceptance must be carried out. After the problems identified are carefully implemented and rectified, the process of installing the gypsum plasterboard can be performed.
When installing the wall keel, it must be prevented that the keel of the wall is not in the same plane. The vertical keel with unqualified straightness should be avoided and the external keel force should be used to place it. This will cause the entire keel side not in the same plane and affect the fixed quality of the gypsum board and the keel.
When installing the ceiling, it is necessary to lift the arch according to the regulations, and at the same time avoid the uneven force of the hoisting point. The bottom edge of the faced keel must be in the same plane, and the bottom-flexing material must not be used. When the long keel needs to be attached, the plug-in parts cannot be arranged in a straight line position and should be dislocated properly. The same is true for the joints on partition walls.
3, install paper gypsum board
(1) laying direction, horizontal and vertical fixation
The strength performance and deformation of the gypsum plaster board are determined according to the direction. The longitudinal performance of the board is better than that of the horizontal direction. Therefore , when the ceiling is suspended, the longitudinal direction of the gypsum board is not allowed to be parallel to the surface keel and should be perpendicular to the keel. This is to prevent Deformation and important measures of joint cracking. However, when installing the partition board, it shall be laid longitudinally. The longitudinal length of the board is the same as or close to the floor height, and it has the advantages of being fixed with the vertical keel. In addition, the longitudinally laid joints are beneficial to improve the fire prevention capability.
(2) board installation and connection
Plasterboard must be installed without stress and must be prevented from being forced into place. When installing the wall and ceiling panels, use wood to support the temporary support, and press the panel and skeleton tightly. Undo the support until the screws are fixed. When installing the fixing plate, fix it from the middle of the plate to the four sides and do not work at more points at the same time . After fixing a sheet, install and fix another sheet in order. The connection between the plate and the light steel keel is fixed by a high-strength self-tapping screw, which cannot be fixed after drilling. Use a self-tapping gun to vertically fasten and fasten. The surface of the screw head is embedded in the gypsum board surface approximately 0.5mm.
(3) Gypsum board interface processing
There is a cross bracing at the interface of the board, and the board at the interface is not allowed to “hangâ€. As far as possible, the wall surface has the same specifications as the room height. If transverse seams cannot be avoided, the seams should be offset. The horizontal seams of the partition walls should be staggered and cannot lie on the same keel. The ceiling seams cannot also be in the same line.
Gypsum plaster board needs to be separated from the seam around the installation , ceiling: the board and the surrounding wall edge from the seam of about 5mm, surface paper wrapping the board edge spacing of about 3 ~ 5mm, cutting board edge spacing of about 3 ~ 5mm; partition wall: board and There is a gap of less than 3mm around the partition wall, and the distance between the board and the board is the same as the ceiling.
(4) Joint processing
The joints of the gypsum plasterboard need to be dealt with by special methods. The joints are handled well, which can make the whole structure into one, and the seams are not obvious.
(5) Edge treatment
The longitudinal edges of the paper-wrapped panels are not required to be treated. The cut-out edges of the panels should be treated as follows before caulking: Before the panel is installed, the upper edge of the front cardboard edge is gently chamfered, and then the knife is used to fix the edge. The chamfered face paper layer was opened and the carefully picked up face paper was carefully removed, but the plaster core could not be exposed.
(6) Caulking process
Building partitions and ceilings are in a variety of stress states, so the vertical and horizontal seams of the gypsum plasterboard are subject to various stresses, which require that the panels should be properly left and the caulking materials themselves have sufficient strength and adhesion. As a result, there must be reasonable joint construction techniques and high operating skills to balance tensile stress and avoid cracks.
a. Each type of caulking putty has its own special process. Understanding and mastering the use of caulking putty is a prerequisite for correct caulking.
b. All joint processing procedures should be performed as late as possible, and other procedures must be completed before implementation.
c. Avoid draughts during caulking construction, otherwise joints at this location are prone to cracks.
d. Caulking construction requires meticulous construction and has higher requirements for workers' operating skills.
e. It is recommended to use aluminum alloy strips for clear seams in locations where vibration is used.
In short, as long as the design is reasonable, the raw materials are qualified, and the construction meets the specifications, it is completely possible to avoid
1, the gypsum board volume stability characteristics
General decoration materials are afraid of water, there is the phenomenon of swelling and shrinking, but the gypsum board can be said to be a good performance material in various types of building decoration. This is because industrially used gypsum is formed by heating dihydrate gypsum and discharging crystal water. The gypsum board is shaped and shaped, and water is added to the burned and ground hemihydrate gypsum to again form the important characteristics of the dihydrate gypsum structure. It separates from the gypsum slurry in the form of pin felt-like crystals. During the drying process, micropores are formed and the gypsum building material has a “gypsum respiration†characteristic, that is, when the humidity of the air changes, it can absorb moisture, and it can quickly Emit to go.
The linear expansion and shrinkage of the gypsum board in the air-dry state is negligible. Even if the air humidity reaches 90%, the maximum stretch rate of the gypsum board is only 0.015% in 24 hours. Therefore, this tiny amount of expansion and contraction is not caused by the board. The main cause of surface deformation and cracking of joints.
2. The effect of the strength of the paper plasterboard on the deformation
The structure of the gypsum plaster board is a plate that is tightly bonded together by the gypsum core and the facing paper. The cover paper plays a role in resisting tension and reinforcement, and the cover paper layer has a great influence on the quality of the board. The plate is not useable. The strength and elasticity of the two-dimensional fibers in the cross-machine direction are different, the longitudinal direction is larger than the transverse direction, and the longitudinal bending and deformation resistance are also stronger.
Gypsum board has strong moisture resistance. The paper surface can prolong the time for the board to take in water, but it cannot prevent water absorption. During installation and construction, for a long time or continuous wet soaking, the strength of the paper plaster will decrease. Therefore, wet sheets must not be constructed and installed. However, when the damp plate is ventilated and dried, its strength and deformation resistance can still be restored.
High temperature has a certain influence on the strength of the gypsum board. When the environmental temperature of the gypsum reaches 42°C, the solidified gypsum starts to change the crystal structure and the strength is impaired, so that the gypsum plaster board cannot be directly connected to the heater or the like.
3, the design and construction of light steel keel skeleton structure
The rational design of the skeleton, the use of qualified materials and parts, and the strict control of construction quality are important guarantees for ensuring that the wall and ceiling of the QST system are not deformed or cracked. Errors and omissions in any one of these links can lead to distortion and cracking. For example, the fixation between the gypsum board and the keel, if not in order or fixed, will cause the board to generate internal forces, and the board seams will be sheared, which will cause deformation and cracks; the stiffness and straightness of the light steel keel is not enough, and the spacing is not proper. , will certainly produce deformation cracking.
4. Caulking process is a direct factor in the success or failure of joint processing
Building partitions and suspended ceilings are in a variety of stress states. Therefore, the vertical and horizontal joints of the gypsum plasterboard are subject to a variety of stresses. This requires that the panels should be properly left and the caulking materials themselves have sufficient strength. And cohesion, but also have a reasonable joint construction process and high operating skills, in order to balance the tensile stress, to avoid cracks. At present, there is no clear regulation on the material design for caulking, and most of the construction units randomly choose caulking putty, whose strength can not meet the requirements; some construction units use high-grade plastic materials, but the price is expensive; some construction units use perforated paper tape to strengthen, Or with grid reinforcement, construction processes are also different, construction season and the environment is different. Therefore, how to grasp the caulking process is very important.
5, the impact of non-orderly and uncivilized construction
After the completion of the caulking process, even after the wallpaper paint is applied, the installation work of the water, electricity, and wind on the ceiling in the wall has not been completed, and the installer will step on the skeleton of the dragon or skid the fixed panel. Cracks in the seams even deform the board surface. Some ceiling design is not on the people, some operators also stepped on the sub-keel, so that the deformation of the skeleton deformation, this situation is especially common in the rush schedule project, we must strengthen management to be overcome.
Second, to avoid distortion and crack design points
1. Reasonable selection of light steel keel and accessories
The skeleton of the partition wall is made of light steel keel. Its strength, stiffness and flatness are indicators of the quality of the skeleton. If the straightness of the keel is not good, the skeleton will not be smooth. After the gypsum board is installed on the keel, internal stress will be generated, and the internal stress will inevitably lead to cracking at the seam of the board during the release process. Therefore, while designing the primary and secondary keel specifications, the design shall also require the stiffness and straightness of the drawings in accordance with national standards. Do not ignore the primary and secondary keel suspensions, connectors, and extensions. Choose a reliable specification. Ensure that the installed skeleton is in an unstressed state and effectively avoid cracking of the gypsum board joints.
2, the choice of gypsum board
There are three types of plain gypsum board, waterproof type and fireproof type. The design can be selected according to different usage requirements, different regions and construction seasons. The partition wall is generally 12 thick. The spacing between the ceiling keel and the thickness of the gypsum board is related. The ceiling is 12 thick. If the thickness is 9.5, the spacing between the keel should be reduced. When there is a high requirement for moisture resistance, such as spraying on the surface of the board, a waterproof layer should be added on the surface of the board, a layer of water-resistant putty or a colorless waterproof agent can be scraped.
Gypsum plasterboard is a covering material for partition walls. It is tightly fixed with high-strength self-tapping screws and light steel keels. If the gypsum board and keel can not be firmly fixed, the gypsum board joints when external forces act. There will be shear forces at the place, leading to cracks in the board seams, so the strength of the gypsum board and the quality of the edge formation are important factors.
The National Cultural Palace selected the dragon brand gypsum board, which has the characteristics of high strength, good toughness, uniform foaming, and full molding at the edges.
3, caulking material
Caulking materials include seam strips and caulking putties. The seams have a good self-adhesive ability and strength and act as stiffeners at the board seams. Caulking putty should not only have good strength and adhesion, but also have certain toughness and good construction performance. If you do not meet the above requirements, cracks will inevitably occur.
Third, to avoid deformation and cracks construction points
1, the construction environment
Do not put gypsum boards in a damp, ventilated place during construction. Do not install paper plasterboard until the relevant wet job is completed.
2, install light steel dragon skeleton
The construction must be carried out strictly according to the drawings and specifications, and the spacing between the keel and the hanging bars must not be arbitrarily increased. The installed skeleton must be in an unstressed state (except for the influence of its own weight ). After the construction is completed, an intermediate acceptance must be carried out. After the problems identified are carefully implemented and rectified, the process of installing the gypsum plasterboard can be performed.
When installing the wall keel, it must be prevented that the keel of the wall is not in the same plane. The vertical keel with unqualified straightness should be avoided and the external keel force should be used to place it. This will cause the entire keel side not in the same plane and affect the fixed quality of the gypsum board and the keel.
When installing the ceiling, it is necessary to lift the arch according to the regulations, and at the same time avoid the uneven force of the hoisting point. The bottom edge of the faced keel must be in the same plane, and the bottom-flexing material must not be used. When the long keel needs to be attached, the plug-in parts cannot be arranged in a straight line position and should be dislocated properly. The same is true for the joints on partition walls.
3, install paper gypsum board
(1) laying direction, horizontal and vertical fixation
The strength performance and deformation of the gypsum plaster board are determined according to the direction. The longitudinal performance of the board is better than that of the horizontal direction. Therefore , when the ceiling is suspended, the longitudinal direction of the gypsum board is not allowed to be parallel to the surface keel and should be perpendicular to the keel. This is to prevent Deformation and important measures of joint cracking. However, when installing the partition board, it shall be laid longitudinally. The longitudinal length of the board is the same as or close to the floor height, and it has the advantages of being fixed with the vertical keel. In addition, the longitudinally laid joints are beneficial to improve the fire prevention capability.
(2) board installation and connection
Plasterboard must be installed without stress and must be prevented from being forced into place. When installing the wall and ceiling panels, use wood to support the temporary support, and press the panel and skeleton tightly. Undo the support until the screws are fixed. When installing the fixing plate, fix it from the middle of the plate to the four sides and do not work at more points at the same time . After fixing a sheet, install and fix another sheet in order. The connection between the plate and the light steel keel is fixed by a high-strength self-tapping screw, which cannot be fixed after drilling. Use a self-tapping gun to vertically fasten and fasten. The surface of the screw head is embedded in the gypsum board surface approximately 0.5mm.
(3) Gypsum board interface processing
There is a cross bracing at the interface of the board, and the board at the interface is not allowed to “hangâ€. As far as possible, the wall surface has the same specifications as the room height. If transverse seams cannot be avoided, the seams should be offset. The horizontal seams of the partition walls should be staggered and cannot lie on the same keel. The ceiling seams cannot also be in the same line.
Gypsum plaster board needs to be separated from the seam around the installation , ceiling: the board and the surrounding wall edge from the seam of about 5mm, surface paper wrapping the board edge spacing of about 3 ~ 5mm, cutting board edge spacing of about 3 ~ 5mm; partition wall: board and There is a gap of less than 3mm around the partition wall, and the distance between the board and the board is the same as the ceiling.
(4) Joint processing
The joints of the gypsum plasterboard need to be dealt with by special methods. The joints are handled well, which can make the whole structure into one, and the seams are not obvious.
(5) Edge treatment
The longitudinal edges of the paper-wrapped panels are not required to be treated. The cut-out edges of the panels should be treated as follows before caulking: Before the panel is installed, the upper edge of the front cardboard edge is gently chamfered, and then the knife is used to fix the edge. The chamfered face paper layer was opened and the carefully picked up face paper was carefully removed, but the plaster core could not be exposed.
(6) Caulking process
Building partitions and ceilings are in a variety of stress states, so the vertical and horizontal seams of the gypsum plasterboard are subject to various stresses, which require that the panels should be properly left and the caulking materials themselves have sufficient strength and adhesion. As a result, there must be reasonable joint construction techniques and high operating skills to balance tensile stress and avoid cracks.
a. Each type of caulking putty has its own special process. Understanding and mastering the use of caulking putty is a prerequisite for correct caulking.
b. All joint processing procedures should be performed as late as possible, and other procedures must be completed before implementation.
c. Avoid draughts during caulking construction, otherwise joints at this location are prone to cracks.
d. Caulking construction requires meticulous construction and has higher requirements for workers' operating skills.
e. It is recommended to use aluminum alloy strips for clear seams in locations where vibration is used.
In short, as long as the design is reasonable, the raw materials are qualified, and the construction meets the specifications, it is completely possible to avoid
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