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Grouting Sleeve, Grouting Material And Application For Prefabricated Steel Bar Connection

- Nov 20, 2018 -

Core Tip: In recent years, China's building industrialization has developed rapidly. The assembled concrete structure has shown its advantages in urban residential construction. The environmental protection and short construction period have also made the city reduce environmental pollution and atmospheric smog. contribution. With the development of the application of fabricated concrete structures, some local-level design and construction standards have been issued one after another. The national industry standards for related products have been promulgated and implemented, and the application of fabricated concrete structures is about to enter a stage of rapid development. The connection technology of prestressed steel bars is the key to directly affecting the safety of fabricated concrete structures. It has become one of the focuses of the fabricated concrete structure related industry, and the steel sleeve grouting connection technology is recognized as the most Mature and reliable solutions will be widely used in industrial buildings in China.

1 Introduction

In recent years, China's building industrialization has developed rapidly. The assembled concrete structure has shown its advantages in urban residential construction. The environmental protection and short construction period have also contributed to the city's reduction of environmental pollution and atmospheric haze. With the development of the application of prefabricated concrete structures, some local-level design and construction standards have been issued one after another. The national standards of relevant products have been promulgated and implemented successively. The industry technical standard of the Ministry of Housing and Urban-Rural Development, which is long-awaited in the industry, “Technical Specifications for Prefabricated Concrete Structures” JGJ1-2014 has been officially approved for release (starting from October 1, 2014), and the application of fabricated concrete structures is about to enter a stage of rapid development. The connection technology of prestressed steel bars is the key to directly affecting the safety of fabricated concrete structures. It has become one of the focuses of the fabricated concrete structure related industry, and the steel sleeve grouting connection technology is recognized as the most Mature and reliable solutions will be widely used in industrial buildings in China.

2 steel grouting joints and applications

2.1 Grouting connection technology principle and joint structure form

The steel sleeve grouting joint consists of ribbed steel bars, grouting sleeves and special grouting.

The connection technology principle is: after connecting the steel bar into the sleeve, the special grout is poured into the sleeve, filling the gap between the sleeve and the steel bar, and the grouting hardens to form tight mesh with the steel bar transverse rib and the inner wall of the sleeve, and is in the steel bar Effective force transmission between the sleeve and the two steel bars

The grouting in this paper refers specifically to cement-based grouting, while the sleeve grouting connection using molten metal material, called molten metal grouting joint, is beyond the scope of this paper.

According to the way of connecting the steel bar and the connecting sleeve, it is divided into two types: full grouting and semi-grouting.

The full grouting joint is a traditional form of grouting connection. The connecting sleeve and the steel bars at both ends are all connected by grouting. The steel bars at both ends must be ribbed steel bars.

The semi-grouting joint is a new type of grouting connection. The connecting sleeve is connected with the one end of the steel bar by grouting connection, and the other end is connected by mechanical connection. The mechanical connection methods of the existing application are straight threaded connection and taper threaded connection. .

Grouting sleeve, grouting material and application for prefabricated steel bar connection

Figure 1 Schematic diagram of grouting joint structure

  2.2 Joint application in concrete structures

  Reinforced sleeve grout joints are permitted for use in the following concrete structures:

  1) Vertical steel joints of prefabricated columns and prefabricated shear walls. A semi-grout joint or a full grout joint can be used.

  2) The longitudinal reinforcement joint of the post-casting section at the joint of the lower part of the prefabricated composite beam. Use a full grout joint.

  Since the jointed steel joints of the prefabricated components have to be arranged in the same section, it is clearly stated in the Technical Specification for Assembled Concrete Structures JGJ1-2014 that the longitudinal steel bars connected by sleeve grouting should meet the current national industry standard "Rebar Machinery". Performance requirements for connection level I joints in Class I joints in JGJ107.

  Whether the joint meets the performance requirements of the class I joint, and is judged by the joint type test specified by JGJ107, including: uniaxial tension, high stress repeated tension and compression, and large deformation repeated tension and compression test, the deformation performance of the joint and Tensile strength is tested, and all joints that meet the performance index of Class I joints can be judged as Class I joints. The sleeve grouting joints of different specifications of steel bars shall be separately type tested.

 

  3 grouting sleeve for steel connection

  3.1 Sleeve structure form

  The national industry standard "grouting sleeve for reinforcing steel connection" JG/T398-2012 divides the grouting sleeve into casting grouting sleeve and mechanical processing grouting sleeve according to the processing method. According to the structural form, it is divided into full grouting sleeve and semi-grouting sleeve. See Figure 2.

 Grouting sleeve, grouting material and application for prefabricated steel bar connection2

  L: total length of grouting sleeve; L0: anchoring length; L1: pre-made end reserved steel bar installation adjustment length; L2: field assembly end reserved steel bar installation adjustment length

  T: wall thickness of grouting sleeve; d: outer diameter of grouting sleeve; D: nominal diameter of internal thread; D1: basic diameter of thread;

  D2: diameter of the through hole at the joint between the threaded end of the semi-grouting sleeve and the grouting end; D3: the inner diameter of the annular protruding portion of the anchoring section of the grouting sleeve

  Figure 2 Schematic diagram of grouting sleeve structure

  3.2 General provisions of JG/T398

  In order to ensure the bearing capacity of the cross section of the sleeve, the design of the yield bearing capacity and tensile bearing capacity of the middle of the full grouting sleeve and the position of the discharge hole of the semi-grouting sleeve after the maximum negative tolerance is calculated shall comply with the provisions of JGJ 107.

  In order to ensure the anchoring capacity of the grout in the sleeve to the steel bar, the anchorage length L0 of the grouting sleeve grouting joint end should not be less than 8 times the bar diameter.

  In order to ensure that the length L of the steel bar installed in the sleeve is within the allowable deviation range, the length of the steel bar in the sleeve is not shorter than the anchor length determined by the joint type test, and the longest is not more than the maximum depth of the sleeve grouting cavity, and the middle of the grouting sleeve The length of the steel bar installation adjustment should be reserved on both sides of the axial positioning point. The prefabricated end L1 should not be less than 10mm, and the field assembly end L2 should not be less than 20mm.

  In order to ensure the anchoring ability of the sleeve grouting cavity to the grouting material, the number of shearing grooves provided in the cavity shall comply with the provisions of Table 2; the axial thickness of the bosses on both sides of the shearing groove shall not be less than 2 mm.

 

  When the grouting sleeve is made by casting process, ductile iron should be used. When manufacturing by mechanical processing, high-quality carbon structural steel, low-alloy high-strength structural steel, alloy structural steel or other steels that meet the requirements through joint type inspection should be selected. Grouting sleeve made of ductile iron, the material should meet the requirements of GB/T 1348, and its material properties should meet the requirements of Table 3. Grouting sleeves made of high-quality carbon structural steel, low-alloy high-strength structural steel and alloy structural steel shall have mechanical properties in accordance with GB/T 699, GB/T 8162, GB/T 1591 and GB/T 3077. Provision.

 

 

  3.5 sleeve appearance quality

  The quality requirements for the grouting sleeve of JG/T398 are as follows:

  The inner and outer surfaces of the grouting sleeve processed by the casting process shall not have quality defects such as slag inclusion, cold partition, blisters, shrinkage holes and cracks which affect the performance. The surface of the grouting sleeve processed by the machining process shall not have cracks or other defects affecting the joint performance; the edges of the Grouting sleeve, grouting material and application for prefabricated steel bar connection

Core Tip: In recent years, China's building industrialization has developed rapidly. The assembled concrete structure has shown its advantages in urban residential construction. The environmental protection and short construction period have also made the city reduce environmental pollution and atmospheric smog. contribution. With the development of the application of fabricated concrete structures, some local-level design and construction standards have been issued one after another. The national industry standards for related products have been promulgated and implemented, and the application of fabricated concrete structures is about to enter a stage of rapid development. The connection technology of prestressed steel bars is the key to directly affecting the safety of fabricated concrete structures. It has become one of the focuses of the fabricated concrete structure related industry, and the steel sleeve grouting connection technology is recognized as the most Mature and reliable solutions will be widely used in industrial buildings in China.

1 Introduction

In recent years, China's building industrialization has developed rapidly. The assembled concrete structure has shown its advantages in urban residential construction. The environmental protection and short construction period have also contributed to the city's reduction of environmental pollution and atmospheric haze. With the development of the application of prefabricated concrete structures, some local-level design and construction standards have been issued one after another. The national standards of relevant products have been promulgated and implemented successively. The industry technical standard of the Ministry of Housing and Urban-Rural Development, which is long-awaited in the industry, “Technical Specifications for Prefabricated Concrete Structures” JGJ1-2014 has been officially approved for release (starting from October 1, 2014), and the application of fabricated concrete structures is about to enter a stage of rapid development. The connection technology of prestressed steel bars is the key to directly affecting the safety of fabricated concrete structures. It has become one of the focuses of the fabricated concrete structure related industry, and the steel sleeve grouting connection technology is recognized as the most Mature and reliable solutions will be widely used in industrial buildings in China.

2 steel grouting joints and applications

2.1 Grouting connection technology principle and joint structure form

The steel sleeve grouting joint consists of ribbed steel bars, grouting sleeves and special grouting.

The connection technology principle is: after connecting the steel bar into the sleeve, the special grout is poured into the sleeve, filling the gap between the sleeve and the steel bar, and the grouting hardens to form tight mesh with the steel bar transverse rib and the inner wall of the sleeve, and is in the steel bar Effective force transmission between the sleeve and the two steel bars

The grouting in this paper refers specifically to cement-based grouting, while the sleeve grouting connection using molten metal material, called molten metal grouting joint, is beyond the scope of this paper.

According to the way of connecting the steel bar and the connecting sleeve, it is divided into two types: full grouting and semi-grouting.

The full grouting joint is a traditional form of grouting connection. The connecting sleeve and the steel bars at both ends are all connected by grouting. The steel bars at both ends must be ribbed steel bars.

The semi-grouting joint is a new type of grouting connection. The connecting sleeve is connected with the one end of the steel bar by grouting connection, and the other end is connected by mechanical connection. The mechanical connection methods of the existing application are straight threaded connection and taper threaded connection. .

 

Figure 1 Schematic diagram of grouting joint structure

  2.2 Joint application in concrete structures

  Reinforced sleeve grout joints are permitted for use in the following concrete structures:

  1) Vertical steel joints of prefabricated columns and prefabricated shear walls. A semi-grout joint or a full grout joint can be used.

  2) The longitudinal reinforcement joint of the post-casting section at the joint of the lower part of the prefabricated composite beam. Use a full grout joint.

  Since the jointed steel joints of the prefabricated components have to be arranged in the same section, it is clearly stated in the Technical Specification for Assembled Concrete Structures JGJ1-2014 that the longitudinal steel bars connected by sleeve grouting should meet the current national industry standard "Rebar Machinery". Performance requirements for connection level I joints in Class I joints in JGJ107.

  Whether the joint meets the performance requirements of the class I joint, and is judged by the joint type test specified by JGJ107, including: uniaxial tension, high stress repeated tension and compression, and large deformation repeated tension and compression test, the deformation performance of the joint and Tensile strength is tested, and all joints that meet the performance index of Class I joints can be judged as Class I joints. The sleeve grouting joints of different specifications of steel bars shall be separately type tested.

 

  3 grouting sleeve for steel connection

  3.1 Sleeve structure form

  The national industry standard "grouting sleeve for reinforcing steel connection" JG/T398-2012 divides the grouting sleeve into casting grouting sleeve and mechanical processing grouting sleeve according to the processing method. According to the structural form, it is divided into full grouting sleeve and semi-grouting sleeve. See Figure 2.

 

  L: total length of grouting sleeve; L0: anchoring length; L1: pre-made end reserved steel bar installation adjustment length; L2: field assembly end reserved steel bar installation adjustment length

  T: wall thickness of grouting sleeve; d: outer diameter of grouting sleeve; D: nominal diameter of internal thread; D1: basic diameter of thread;

  D2: diameter of the through hole at the joint between the threaded end of the semi-grouting sleeve and the grouting end; D3: the inner diameter of the annular protruding portion of the anchoring section of the grouting sleeve

  Figure 2 Schematic diagram of grouting sleeve structure

  3.2 General provisions of JG/T398

  In order to ensure the bearing capacity of the cross section of the sleeve, the design of the yield bearing capacity and tensile bearing capacity of the middle of the full grouting sleeve and the position of the discharge hole of the semi-grouting sleeve after the maximum negative tolerance is calculated shall comply with the provisions of JGJ 107.

  In order to ensure the anchoring capacity of the grout in the sleeve to the steel bar, the anchorage length L0 of the grouting sleeve grouting joint end should not be less than 8 times the bar diameter.

  In order to ensure that the length L of the steel bar installed in the sleeve is within the allowable deviation range, the length of the steel bar in the sleeve is not shorter than the anchor length determined by the joint type test, and the longest is not more than the maximum depth of the sleeve grouting cavity, and the middle of the grouting sleeve The length of the steel bar installation adjustment should be reserved on both sides of the axial positioning point. The prefabricated end L1 should not be less than 10mm, and the field assembly end L2 should not be less than 20mm.

  In order to ensure the anchoring ability of the sleeve grouting cavity to the grouting material, the number of shearing grooves provided in the cavity shall comply with the provisions of Table 2; the axial thickness of the bosses on both sides of the shearing groove shall not be less than 2 mm.

 

  When the grouting sleeve is made by casting process, ductile iron should be used. When manufacturing by mechanical processing, high-quality carbon structural steel, low-alloy high-strength structural steel, alloy structural steel or other steels that meet the requirements through joint type inspection should be selected. Grouting sleeve made of ductile iron, the material should meet the requirements of GB/T 1348, and its material properties should meet the requirements of Table 3. Grouting sleeves made of high-quality carbon structural steel, low-alloy high-strength structural steel and alloy structural steel shall have mechanical properties in accordance with GB/T 699, GB/T 8162, GB/T 1591 and GB/T 3077. Provision.

 

 

  3.5 sleeve appearance quality

  The quality requirements for the grouting sleeve of JG/T398 are as follows:

  The inner and outer surfaces of the grouting sleeve processed by the casting process shall not have quality defects such as slag inclusion, cold partition, blisters, shrinkage holes and cracks which affect the performance. The surface of the grouting sleeve processed by the machining process shall not have cracks or other defects affecting the joint performance; the edges of the end face and the outer surface of the grouting sleeve shall be free of sharp edges and burrs.

  3.6 Mechanical properties of the sleeve

  "Grinding sleeve for reinforcing steel connection" JG/T398 requires that the grouting sleeve should be matched with the grouting material. The tensile strength of the steel joint connected by the grouting sleeve should meet the requirements of the I-level joint in JGJ107.

  3.7 JM grouting sleeve

  Beijing Sida Jianmao JM grouting sleeve products include: CT series grouting straight threaded sleeve (semi-grouting sleeve) for prefabricated shear wall and prefabricated column vertical steel bar connection, CTH series full grouting for prefabricated laminated beam horizontal steel bar connection Sleeve.

  The CT series grouting straight threaded sleeve and CTH series grouting sleeve are characterized by:

  1) The sleeve material is made of high-quality carbon structural steel material with high strength, good toughness and stable performance. 2) The internal structure of the sleeve is processed by high-precision CNC machine tool with precise dimensions and high reliability. 3) The sleeve is built in Beijing. The technical achievements of the national invention patents: multi-section, double-slope shear groove grouting cavity structure, see Figure 3, the sleeve size is reduced to the smallest, better than foreign grouting sleeve products.nd face and the outer surface of the grouting sleeve shall be free of sharp edges and burrs.

  3.6 Mechanical properties of the sleeve

  "Grinding sleeve for reinforcing steel connection" JG/T398 requires that the grouting sleeve should be matched with the grouting material. The tensile strength of the steel joint connected by the grouting sleeve should meet the requirements of the I-level joint in JGJ107.

  3.7 JM grouting sleeve

  Beijing Sida Jianmao JM grouting sleeve products include: CT series grouting straight threaded sleeve (semi-grouting sleeve) for prefabricated shear wall and prefabricated column vertical steel bar connection, CTH series full grouting for prefabricated laminated beam horizontal steel bar connection Sleeve.

  The CT series grouting straight threaded sleeve and CTH series grouting sleeve are characterized by:

  1) The sleeve material is made of high-quality carbon structural steel material with high strength, good toughness and stable performance. 2) The internal structure of the sleeve is processed by high-precision CNC machine tool with precise dimensions and high reliability. 3) The sleeve is built in Beijing. The technical achievements of the national invention patents: multi-section, double-slope shear groove grouting cavity structure, see Figure 3, the sleeve size is reduced to the smallest, better than foreign grouting sleeve products.

Grouting sleeve, grouting material and application for prefabricated steel bar connection3