Construction method for preventing joint of prefabricated wallboard and cast-in-place structure from cracking

Abstract

The invention relates to a construction method for avoiding cracking of the joint of a prefabricated wall panel and a cast-in-place structure. The construction method comprises the steps that firstly, a prefabricated wall body is installed and fixed, and rib binding and mold closing are conducted on a cast-in-place section; 2, processing a pouring raw material, and adding an expanding agent into concrete used for pouring a cast-in-place section at the joint of the prefabricated wall body; 3, treating the joint part after the mold is removed; and fourthly, the connection portions of all the prefabricated wall bodies and the cast-in-place sections are treated. The connecting effect of the cast-in-place structure and the prefabricated part of the prefabricated assembly type building is enhanced, the problem of cracks at the joint of the prefabricated wallboard and the cast-in-place structure can be effectively solved, the safety and stability of the structure are improved, and the quality and the service life of the building are guaranteed.

Description

Technical Field

[0001] The invention relates to the field of civil engineering, in particular to a construction method for avoiding cracking at the junction of a prefabricated wall panel and a cast-in-place structure. Background Art

[0002] In construction, cracks are prone to occur at the junction of prefabricated wall panels and cast-in-place structures. This is because there are differences in material properties, shrinkage rates, etc. between prefabricated wall panels and cast-in-place structures, and there are certain deformations and stress concentrations during the construction process. If not handled, the crack problem will cause quality problems such as leakage of the exterior wall and shedding of the decorative layer. First of all, the verticality of the prefabricated wall panels should be ensured to be no more than 3mm. At the same time, the quality of the sleeve grouting should be strictly controlled, because the tensile strength value of the grouting sleeve directly determines the stability of the wall. If the stability cannot be guaranteed, cracks will inevitably appear at the junction with the cast-in-place section.

[0003] The junction between the existing prefabricated wall panels and the cast-in-place structure is a weak point, which can easily lead to cracks. Because the junction between the prefabricated wall panels and the cast-in-place structure is poured later, the concrete will expand and contract with heat and cold, and the stress effect of the junction is poor, it is inevitable that cracks will appear at the junction between the prefabricated wall panels and the cast-in-place structure. Summary of the invention

[0004] The present invention aims to overcome the defects of the prior art, provide a construction method for avoiding cracks at the junction of prefabricated wall panels and cast-in-place structures, and solve the problem of cracks at the junction of assembled prefabricated walls and cast-in-place structures.

[0005] In order to solve the above-mentioned technical problems, the present invention is achieved as follows: A construction method for avoiding cracking at the junction of a prefabricated wall panel and a cast-in-place structure, characterized in that it comprises the following steps: Step 1: Installation and fixation of prefabricated walls and reinforcement moulding of cast-in-place sections; Step 2: Add expansion agent to the concrete used for pouring the cast-in-place section at the junction of the prefabricated wall; Step 3: Handling of joints after formwork removal After formwork removal, all joints between prefabricated walls and cast-in-place sections shall be checked immediately, and all those with verticality exceeding the allowable range shall be recorded according to the prefabricated wall number; the cracks shall be grooved in the shape of a trapezoidal groove with an upper opening, a width of 2cm on the outer surface, and a lower opening inside the crack, a width of 1cm and a depth of 1cm, and elastic material shall be applied to the groove; both sides of the groove shall be extended by 5cm for roughening, and the trapezoidal groove shall be covered with a 10cm wide steel wire mesh, the grouting material shall be smoothed, and the formwork shall be supported to press it down; Step 4: Treat the junction of all prefabricated walls and cast-in-place sections: apply 300mm wide 1.5mm thick Type II JS waterproof coating + 12mm thick DP M15 cement mortar (mixed with 5% waterproofing agent) for base brushing + press a layer of 300mm wide alkali-resistant glass fiber mesh cloth + 8mm thick DP M20 cement mortar (mixed with 5% waterproofing agent) into the junction of the prefabricated section and the cast-in-place section, smooth it, and then scrape it with whitewash.

[0006] The construction method for avoiding cracking at the junction of prefabricated wall panels and cast-in-place structures is characterized in that: the step one specifically includes: prefabricated wall panel installation preparation → hoisting prefabricated wall panels → quick positioning → prefabricated wall panel oblique support installation → prefabricated wall panel fine adjustment → prefabricated wall panel grouting operation → cast-in-place node reinforcement binding → cast-in-place node formwork between prefabricated wall panels.

[0007] The construction method for avoiding cracking at the junction of prefabricated wall panels and cast-in-place structures is characterized in that: during the "fine-tuning of prefabricated wall panels", the verticality of the wall is ensured, and the S verticality requirement does not exceed 3mm.

[0008] The construction method for avoiding cracking at the junction of prefabricated wall panels and cast-in-place structures is characterized in that during the "prefabricated wall panel grouting operation", the tensile strength value of the grouting sleeve directly determines the stability of the wall, and the tensile strength value of the grouting sleeve is higher than the standard value of the tensile strength of the connecting steel bars.

[0009] The construction method for avoiding cracking at the junction of prefabricated wall panels and cast-in-place structures is characterized in that: during the "installation of prefabricated wall panels and cast-in-place node templates", before installing the template at the tongue and groove of the prefabricated wall, elastic material is applied on both sides of the edge of the contact surface between the prefabricated wall and the cast-in-place section, the template is aligned with the tongue and groove and pressed to complete the installation, and is fully vibrated during pouring.

[0010] The construction method for avoiding cracking at the junction of the prefabricated wall panel and the cast-in-place structure is characterized in that the elastic material is glass glue.

[0011] The beneficial effects of the present invention are as follows: It can be seen from the above technical solution that the present application provides a construction method for avoiding cracking at the junction of prefabricated wall panels and cast-in-place structures. Compared with the traditional methods, the advantages and beneficial effects of the present invention patent are not available in the traditional methods. The present patent has the advantages of improving structural stability, convenient maintenance, and precise control. The present patent solves the problem of cracks at the junction of prefabricated prefabricated walls and cast-in-place structures, and strengthens the connection effect between the cast-in-place structure of prefabricated assembled buildings and prefabricated components. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments: Figure 1This is a schematic diagram of the application process.

[0013] Figure 2 This is a schematic diagram of the structure of this application. DETAILED DESCRIPTION

[0014] The technical solutions of the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments in the embodiments of the present application are within the scope of protection requested by the present application. like Figure 1 , 2 As shown: A construction method for avoiding cracking at the junction of a prefabricated wall panel and a cast-in-place structure, comprising: 1. Installation and fixation of prefabricated walls and reinforcement moulding of cast-in-place sections; Preparation for precast wall panel installation → Lifting precast wall panels → Quick positioning → Installation of precast wall panel inclined supports → Fine-tuning of precast wall panels → Grouting operation of precast wall panels → Reinforcement binding of cast-in-place nodes → Formwork support for cast-in-place nodes between precast wall panels.

[0015] The construction process of prefabricated walls in construction site operations is as follows Figure 1 (Water and electricity professionals are allowed to intersperse construction by default) The main purpose of the "fine adjustment of prefabricated wall panels" in the process is to ensure the verticality of the wall. If the verticality exceeds the allowable deviation, the wall will inevitably fall to one side due to its weight, and the force generated will inevitably tear the connection between the prefabricated wall and the cast-in-place section, resulting in cracks. Therefore, we stipulate that the verticality requirement should not exceed 3mm.

[0016] "Prefabricated wall grouting operation" must be strictly carried out according to the instructions. The tensile strength of the grouting sleeve directly determines the stability of the wall. If the stability cannot be guaranteed, cracks will inevitably appear at the junction with the cast-in-place section, and even affect the safety of the structure. The tensile strength of the grouting sleeve must be higher than the standard tensile strength of the connecting steel bars.

[0017] The last step, "installation of templates for prefabricated wall panels and cast-in-place nodes", is the most critical. Before installing the templates at the prefabricated wall tongue and groove, apply elastic materials (such as glass glue) on both sides of the edges of the contact surface between the prefabricated wall and the cast-in-place section, align the templates with the tongue and groove to complete the installation, and fully vibrate during pouring. Regardless of cracks in the prefabricated wall and the cast-in-place section or uneven settlement on both sides causing squeezing, the elastic materials will fill or be squeezed and deformed, and no cracks will appear.

[0018] 2. The processing of raw materials for casting and the concrete used for casting the cast-in-place section at the junction of prefabricated walls require the commercial concrete mixing station to add an appropriate amount of expansion agent within a controllable range to reduce the risk of cracks.

[0019] 3. Handling of the joints after demolding After demolding, conduct a thorough investigation of all joints between prefabricated walls and cast-in-place sections as soon as possible, and record all those that are unqualified by naked eye and whose verticality exceeds the allowable range according to the prefabricated wall number. Arrange a construction team to groove the cracks according to the record sheet. The shape is a trapezoidal groove with a width of 2cm at the upper mouth (outer surface), a width of 1cm at the lower mouth (inside the crack), and a depth of 1cm. Apply elastic material inside the groove. Extend 5cm on both sides of the groove for roughening, cover the trapezoidal groove with a 10cm wide steel wire mesh, smooth the grouting material, and support the template to press it down.

[0020] 4. During the decoration and renovation construction, all the joints between prefabricated walls and cast-in-place sections shall be treated: brush 300mm wide 1.5mm thick Type II JS waterproof coating + 12mm thick DP M15 cement mortar (mixed with 5% waterproofing agent) for base brushing + press a layer of 300mm wide alkali-resistant glass fiber mesh cloth + 8mm thick DP M20 cement mortar (mixed with 5% waterproofing agent) into the joints between the prefabricated section and the cast-in-place section, smooth it, and then scrape it with whitewash.

[0021] Compared with traditional methods, the present invention has more precise wall panel installation requirements in the fine adjustment of the upper wall panel to ensure the verticality of the wall (verticality deviation <3mm). If the verticality exceeds the allowable deviation, the force generated will inevitably tear the connection between the prefabricated wall and the cast-in-place section, resulting in cracks. Secondly, in the stage of "installation of templates for prefabricated wall panels and cast-in-place nodes", the main method of the present invention is that before installing the template at the tongue and groove of the prefabricated wall, elastic materials (such as glass glue) should be applied on both sides of the edge of the contact surface between the prefabricated wall and the cast-in-place section, and the template should be aligned with the tongue and pressed to complete the installation, and fully vibrated during pouring. When cracks occur between the prefabricated wall panels and the cast-in-place section, the cracks should be grooved in the shape of a trapezoidal groove with an upper opening (outer surface) width of 2 cm, a lower opening (inside the crack) width of 1 cm, and a depth of 1 cm, and elastic materials are applied in the groove. Extend 5 cm on both sides of the groove for roughening, cover the trapezoidal groove with a 10 cm wide steel wire mesh, smooth the grouting material, and support the template to press it. The present application prevents cracks from occurring at the junction of the prefabricated wall panels and the cast-in-place structure to a great extent, and also has a good repair effect on subsequent cracks.

[0022] The benefits it brings: 1. Improve structural stability: Through the construction technology of the present invention, the stability and durability of the junction of prefabricated wall panels and cast-in-place structures can be ensured, and the safety and reliability of the overall structure can be improved. 2. Convenient maintenance: Through the use of this technology, the incidence of cracks at the junction of prefabricated wall panels and cast-in-place structures will be greatly reduced. This technical maintenance method also solves the problem of cracks found after demolding, thereby reducing the cost of later maintenance and repair. 3. Precise control: The junction of prefabricated and cast-in-place structures can be more accurately controlled in size and position, reducing engineering errors, which is impossible with traditional processes.

[0023] This method can effectively and reasonably deal with the crack problem at the junction, and also improves the quality of the construction appearance. This construction method is simple to operate, convenient to construct, and can be made from local materials. All materials used can be selected from on-site construction materials, and this construction method can be used flexibly, is simple to operate, and saves time and effort.

[0024] The above are only embodiments provided for the present application and are not intended to limit the present application. Although the present application is described in detail with reference to the embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A construction method for avoiding cracking at the junction of prefabricated wall panels and cast-in-place structures, characterized in that It includes the following steps: Step 1: Installation and fixation of prefabricated walls and reinforcement moulding of cast-in-place sections; Step 2: Add expansion agent to the concrete used for pouring the cast-in-place section at the junction of the prefabricated wall; Step 3: Handling of joints after formwork removal After formwork removal, all joints between prefabricated walls and cast-in-place sections shall be checked immediately, and all those with verticality exceeding the allowable range shall be recorded according to the prefabricated wall number; the cracks shall be grooved in the shape of a trapezoidal groove with an upper opening, a width of 2cm on the outer surface, and a lower opening inside the crack, a width of 1cm and a depth of 1cm, and elastic material shall be applied to the groove; both sides of the groove shall be extended by 5cm for roughening, and the trapezoidal groove shall be covered with a 10cm wide steel wire mesh, the grouting material shall be smoothed, and the formwork shall be supported to press it down; Step 4: Treat the junction of all prefabricated walls and cast-in-place sections: apply 300mm wide and 1.5mm thick Type II JS waterproof coating + 12mm thick DP M15 cement mortar (mixed with 5% waterproofing agent) for base brushing + press a layer of 300mm wide alkali-resistant glass fiber mesh cloth + 8mm thick DP M20 cement mortar (mixed with 5% waterproofing agent) into the junction of the prefabricated section and the cast-in-place section, smooth it, and then scrape it with whitewash.

2. A construction method for avoiding cracking at the junction of a prefabricated wall panel and a cast-in-place structure according to claim 1, characterized in that: The step one specifically includes: preparation for prefabricated wall panel installation → hoisting prefabricated wall panels → quick positioning → installation of prefabricated wall panel oblique supports → fine adjustment of prefabricated wall panels → grouting operation of prefabricated wall panels → steel bar binding of cast-in-place nodes → formwork support for cast-in-place nodes between prefabricated wall panels.

3. A construction method for avoiding cracking at the junction of a prefabricated wall panel and a cast-in-place structure according to claim 2, characterized in that: During the "fine-tuning of prefabricated wall panels", the verticality of the wall is ensured, and the S verticality requirement is not more than 3mm.

4. A construction method for avoiding cracking at the junction of a prefabricated wall panel and a cast-in-place structure according to claim 2, characterized in that: During the "prefabricated wall panel grouting operation", the tensile strength value of the grouting sleeve directly determines the stability of the wall, and the tensile strength value of the grouting sleeve must be higher than the standard value of the tensile strength of the connecting steel bars.

5. A construction method for avoiding cracking at the junction of a prefabricated wall panel and a cast-in-place structure according to claim 2, characterized in that: During the "installation of prefabricated wall panels and cast-in-place node templates", before installing the template at the tongue and groove of the prefabricated wall, elastic material is applied on both sides of the edge of the contact surface between the prefabricated wall and the cast-in-place section, the template is aligned with the tongue and pressed to complete the installation, and is fully vibrated during pouring.

6. A construction method for avoiding cracking at the junction of a prefabricated wall panel and a cast-in-place structure according to claim 5, characterized in that: The elastic material is glass glue.

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