A method for preventing cracks and leakage in reinforced concrete roofs

Abstract

The present invention proposes a method for preventing cracks and leakage in reinforced concrete roofs, and the construction methods include: investigation and research → formulation of a construction plan → construction and observation tests → numerical analysis → construction optimization. The present invention strengthens the treatment of screw holes and pipe openings in the exterior wall and the details of doors and windows, including filling the bottom of the window with waterproof mortar, applying waterproof material around the window frame, cleaning and sealing the screw holes in the exterior wall, and applying polyurethane. In this way, the risk of leakage in the building is greatly reduced, and the operational risk brought by later repairs is indirectly reduced, while also ensuring that the functionality and practicality of the building are better demonstrated; the self-waterproofing test process of the structure is monitored to find out the weak points of leakage, and the situation that occurs is deeply studied to form a written report, which is monitored in the later construction to improve the self-waterproofing ability of the structure, and further solve the problems of short waterproofing time of waterproof materials and excessive later maintenance costs.

Description

Technical Field

[0001] The invention relates to the technical field of anti-leakage methods, in particular to a method for preventing cracks and leakage in reinforced concrete roofs. Background Art

[0002] In recent years, the construction of construction projects in my country has been increasing, and the construction quality of construction projects has also received more and more attention from the society. Among them, leakage in housing construction projects is one of the most common quality diseases in housing construction, which seriously affects the quality of people's living environment and the actual service life of buildings. Long-term building leakage may also endanger people's lives and property safety; for this reason, construction units should pay attention to anti-leakage technology in the construction process, try to avoid leakage problems in housing buildings, further strengthen the quality management of housing construction, and improve the anti-seepage performance of my country's housing construction projects. Anti-leakage construction technology is one of the important components of housing construction engineering construction, and the quality of construction has a great impact on housing. It has a direct impact on the overall construction quality and service life of the house construction project; in house construction, construction workers must pay more attention to anti-leakage construction technology; in addition, compared with other construction projects, house construction projects are very different from them. House construction projects are the main places for people's daily life and residence. Once a leakage problem occurs, it will not only affect people's daily life, but also bring hidden dangers to people's living safety. Under long-term erosion by moisture, the walls in the house will naturally expand and peel, and even cause deformation of the ceiling and suspended ceiling; the wall will become weaker and weaker under long-term corrosion, resulting in a decrease in the overall compressive resistance of the house and a shortened service life. Living in a humid environment for a long time, people are prone to diseases such as arthritis, and even many bacteria will breed in the house, affecting people's health. It can be seen that in the construction of houses, the importance of anti-leakage construction technology is self-evident and must be taken seriously. At present, preventing leakage in building construction projects from occurring in the construction process of buildings, and preventing cracks and leakage in reinforced concrete roofs is a key link. The reasons for leakage are as follows: First, during the construction process, due to the serious loss of cement slurry, honeycomb cavities are formed on the concrete surface, which is prone to crack seepage; second, the concrete material has a low mud content and poor grading, resulting in uniform honeycomb cavities on the surface of the concrete; third, during the mixing process of concrete, the water-cement ratio is not well controlled, and the proportion of water added is too high, resulting in increased porosity and reduced strength of concrete, which is prone to cracks; fourth, due to the temperature of the plate surface during construction, the reinforcement is deformed due to human displacement, and the reinforcement has no hooks, resulting in a short lap length of the reinforcement, which does not play a tensile role. Under the influence of high temperature, it will eventually expand and cracks will seep water. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preventing cracks and leakage in reinforced concrete roofs to solve the problems raised in the above background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for preventing cracks and leakage in reinforced concrete roofs, comprising five steps: investigation and research → construction plan formulation → construction and observation testing → numerical analysis → construction optimization.

[0006] Step 1: Through the investigation of the current situation of crack and leakage prevention in the current building construction project, information research, collection and collation of relevant data, preparation of corresponding technical plans, formulation of safeguard measures, through research group discussion and on-site implementation, modification of relevant technical measures according to the demonstration results;

[0007] (1) Research on structural self-waterproofing test methods.

[0008] (2) Research on one-step molding technology for counter-slope casting of bathrooms, kitchens and balconies.

[0009] (3) Study on the key points of sealing the screw holes in the exterior walls and the bottoms of windows, doors and window frames.

[0010] (4) Research on the post-processing process of reserved casing.

[0011] Step 2: The project department will carry out implementation organization design and plan preparation based on the confirmed technical data, and formulate staffing, material and equipment plans and schedule;

[0012] Step 3: Track and control the entire operation process to ensure the quality of the operation;

[0013] Construction methods

[0014] (1) After the slab reinforcement is tied, place a 3*100mm water stop flat iron (the water stop flat iron is 50mm higher than the slab elevation). When the carpenters lower the slab and "hang the formwork", the bathroom's anti-slope is positioned and supported at the same time. The accuracy of the position and elevation must be ensured during positioning. When pouring concrete, pour the bathroom and kitchen immediately after pouring the wall columns, and then pour the other slab surfaces. Pour the anti-slope of the bathroom and kitchen before the concrete begins to set. During the pouring process, the vibration interval needs to be shortened accordingly. The duration of the tamping should be such that the concrete surface produces floating slurry, no bubbles, and does not sink. The vibrator insertion points are evenly arranged in a plum blossom shape to ensure that the lower part of the anti-slope is dense.

[0015] (2) By sealing the screw holes on the outer wall and the reserved holes on the inner plane of the building, the waterproof function of the structure is further improved. For the screw holes, the PVC pipes in the wall are first removed and cleaned with an impact drill, and the residual mortar around the holes is cleaned. The outer holes are expanded into a 20mm deep trumpet shape as much as possible. Water is sprayed on the outer wall with a spray bottle to keep the area around the bolt holes moist. After the expansion cement waterproof mortar is partially poured in from the outside to the inside of the outer wall with an iron trowel, the foaming agent is injected from the inside until it overflows. After solidification, the polyurethane waterproof material is applied with a thickness of 1.5mm and a diameter of 100mm, with the outer wall bolt hole as the center. For the reserved holes on the inner plane of the building, the reserved casing is first removed and roughened with an impact drill. After the pipe is buried, it is sprayed with water with a spray bottle. After the pipe surface is roughened, micro-expanded fine stone concrete (mixed with 3% waterproofing agent) is used to cast the concrete in two steps.

[0016] (3) After filling the 150mm below the window frame with waterproof mortar, inject foaming agent into the periphery of the window frame. During the foaming process, a baffle is used on the outside to ensure the one-time molding effect of the outer surface of the foaming agent. Then, cement waterproof mortar is used for overall sealing, and JS waterproof coating is applied around the outer periphery of the window frame.

[0017] Construction inspection methods

[0018] Concrete water seepage resistance test: First, prepare concrete materials and mix concrete according to the designed proportion; second, pour concrete into the mold, compact and vibrate it fully; third, cure the concrete specimen; fourth, place the specimen at room temperature of 20℃ and prepare it before the test; fifth, stick a rubber film on the concrete specimen and apply a waterproofing agent; sixth, place the concrete specimen in the Rockwell permeameter laboratory, apply a fixed pressure difference, and measure the concrete penetration within a certain period of time; seventh, record the penetration amount and time, and calculate the concrete's water resistance performance index, adjust the concrete material mix ratio according to the test data, and effectively improve the concrete structure's self-waterproofing ability.

[0019] (2) Water storage test: This test is carried out after the structure is completed and before the waterproof material is applied. The test requires that the roof, bathroom, balcony and other places are filled with water, and the water volume must be sufficient. The water storage depth of the self-waterproofing test is 30 mm, and the water storage time is 24 hours. During this period, it is observed several times for leakage. If there is no leakage, it is qualified. If there is a leakage point, necessary measures should be taken in time. The self-waterproofing of the structure is intended to solve the problem of short waterproofing time of waterproof materials and reduce the subsequent maintenance costs.

[0020] Step 4: Collect data on site and conduct analysis. Analyze the influencing factors by collecting data on site and making statistical tables of quality defect items. Then analyze the reasons for the occurrence of such results, and finally formulate and implement countermeasures.

[0021] Step 5: Construction optimization methods: First, strictly control the mix ratio of concrete materials to ensure that the cement ratio meets the design requirements. It is necessary to control the strength grade of cement, the grading grade of sand and gravel, etc.

[0022] Second, pour in the order of pouring, and vibrate in time to prevent honeycomb and voids in the later stage. During pouring, arrange 1-2 reinforcement workers to adjust the steel bars that are deformed by being stepped on at any time, especially the temperature reinforcement on the slab surface. Do not add water during the concrete pouring process, and do not disturb it after initial setting.

[0023] The third is to strengthen concrete curing. Natural curing should be started before the final setting of the concrete (usually within 8 to 12 hours after the concrete is poured). People are allowed to walk on it only after the compressive strength reaches 5MPa. For cracks on concrete slabs or walls, if the cracks are very wide, a 10mm wide and 10-15mm deep groove should be chiseled along the crack position first. After cleaning, apply a layer of treatment agent, and then fill in synthetic polymer sealing materials and apply polymer cement mortar on the surface. If the cracks are small, epoxy resin can be injected into the cracks to seal them.

[0024] Furthermore, when pouring the concrete, the free fall height of the concrete from the discharge port shall not exceed 2m to prevent the segregation of the falling concrete. Before pouring, the bottom should be filled with 3cm thick cement mortar with the same concrete mix ratio to prevent "root rot". The vibrator should be inserted quickly and pulled out slowly, and the insertion points should be evenly arranged and moved point by point in sequence without omission to ensure uniform vibration. The moving spacing should not be greater than 1.5 times the vibration action radius (generally 20-30cm). When vibrating the upper layer, it should be inserted into the lower layer 5-10cm to ensure a firm bond between the two layers of concrete. After the concrete is poured, a secondary surface finishing treatment should be performed to reduce surface cracks.

[0025] Furthermore, the screw holes, reserved openings, and window frame perimeter were sealed with polyurethane waterproofing material applied to the outermost surface of the screw holes. The reserved casing at the reserved opening was removed and cleaned with a hammer drill, then moistened with water using a spray bottle. A higher-grade, slightly expansive fine stone concrete (with a 3% waterproofing agent) was then poured. The lower 150mm of the window frame was sealed with waterproof mortar. The remaining areas were sealed with foaming agent, then sealed with waterproof mortar and a 100mm-wide coating of JS waterproofing paint was applied to the exterior.

[0026] Furthermore, by monitoring the self-waterproofing test process of the structure, we can find out the weak points of leakage, conduct in-depth research on the situations that occur, and form a written report. Later construction will focus on monitoring to improve the self-waterproofing ability of the structure and further solve the problems of short waterproofing time of waterproof materials and excessive later maintenance costs.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: the method for preventing cracks and leakage in reinforced concrete roofs effectively improves the self-waterproofing ability of concrete structures from multiple aspects such as pouring, process optimization and later maintenance; the concrete counter-ridges of bathrooms, kitchens and balconies are formed in one step, and the vibration interval needs to be shortened accordingly during the pouring process. The tamping duration should be such that floating slurry is generated on the concrete surface without bubbles and without sinking. The vibrator insertion points are evenly arranged in a plum blossom shape to ensure that the lower part of the counter-ridge is dense, thus solving the problem of honeycomb cavities formed on the concrete surface and cracks and water seepage easily occurring; the screw holes and pipe openings in the exterior walls are sealed and the door and window details are strengthened, including This includes using waterproof mortar to fill the bottom of the windows, applying waterproof material around the window frames, cleaning and sealing the screw holes on the exterior walls, and applying polyurethane. In this way, the risk of leakage in the building is greatly reduced, and the operational risks brought by later repairs are indirectly reduced, while also ensuring that the functionality and practicality of the building are better demonstrated; monitoring the structural self-waterproofing test process, identifying weak points of leakage, conducting in-depth research on the situations that arise, and forming a written report. This will be the focus of later construction control to improve the self-waterproofing ability of the structure and further solve the problems of short waterproofing time of waterproof materials and excessive later maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A construction drawing of a reinforced concrete roof crack and leakage prevention method according to the present invention;

[0029] Figure 2 This is a technical roadmap for a reinforced concrete roof crack and leakage prevention method of the present invention. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," "the other end," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "provided with," "connected," etc., should be understood in a broad sense. For example, "connected" may refer to a fixed connection, a detachable connection, or an integral connection; it may refer to a mechanical connection or an electrical connection; it may refer to a direct connection or an indirect connection through an intermediate medium; it may refer to internal communication between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on the specific circumstances. Example 1

[0033] See also Figure 1-2 The embodiment provided by the present invention is a method for preventing cracks and leakage in reinforced concrete roofs. The construction method comprises the following five steps: investigation and research → construction plan formulation → construction and observation test → numerical analysis → construction optimization:

[0034] Step 1: Through the investigation of the current situation of crack and leakage prevention in the current building construction project, information research, collection and collation of relevant data, preparation of corresponding technical plans, formulation of safeguard measures, through research group discussion and on-site implementation, modification of relevant technical measures according to the demonstration results;

[0035] (1) Research on structural self-waterproofing test methods

[0036] The structural self-waterproofing test is carried out after the structure is completed and before the waterproof material is applied. The test requires that the roof, bathroom, balcony and other places be filled with water with sufficient volume. The water storage depth of the self-waterproofing test is 30 mm and the water storage time is 24 hours. During this period, it is observed several times for leakage. If there is no leakage, it is qualified. If there is a leakage point, necessary measures should be taken in time. The structural self-waterproofing aims to solve the problem of short waterproofing time of waterproof materials and reduce the subsequent maintenance costs.

[0037] (2) Research on one-step molding technology for bathroom, kitchen and balcony anti-slope casting

[0038] Due to the special circumstances of the bathroom, kitchen and balcony, there is more exposed water in the bathroom, kitchen and balcony than in other rooms, and the waterproofing requirements are strict. In order to avoid leakage points during the secondary pouring of the anti-slope root, the anti-slope of the bathroom, kitchen and balcony is required to be cast into shape at the same time as the main building concrete.

[0039] (3) Research on the key points of sealing the screw holes in the exterior walls and the bottoms of windows, doors and window frames

[0040] Because the exterior walls, doors and windows need to come into direct contact with rainwater in the future, there is a greater risk of leakage. The impact of leakage is more serious. It will also affect the sound insulation effect of the building, seriously affecting the quality of people's living environment and reducing the actual service life of the building. Long-term building leakage may also endanger people's lives and property safety.

[0041] (4) Study on the post-processing process of reserved casing

[0042] According to the requirements of building construction, the construction of reserved holes is the main link in the construction of building structures. There are a large number of reserved holes in the concentrated areas of pipelines such as water and electricity pipe wells and toilets. The sealing of the holes between multiple floors directly affects the construction quality of the building.

[0043] Step 2: The project department will carry out implementation organization design and plan preparation based on the confirmed technical data, and formulate staffing, material and equipment plans and schedule;

[0044] Step 3: Track and control the entire operation process to ensure the quality of the operation;

[0045] Construction methods

[0046] (1) After the slab reinforcement is tied, place a 3*100mm water stop flat iron (the water stop flat iron is 50mm higher than the slab elevation). When the carpenters lower the slab and "hang the formwork", the bathroom's anti-slope is positioned and supported at the same time. The accuracy of the position and elevation must be ensured during positioning. When pouring concrete, pour the bathroom and kitchen immediately after pouring the wall columns, and then pour the other slab surfaces. Pour the anti-slope of the bathroom and kitchen before the concrete begins to set. During the pouring process, the vibration interval needs to be shortened accordingly. The duration of the tamping should be such that the concrete surface produces floating slurry, no bubbles, and does not sink. The vibrator insertion points are evenly arranged in a plum blossom shape to ensure that the lower part of the anti-slope is dense.

[0047] (2) By sealing the screw holes on the outer wall and the reserved holes on the inner plane of the building, the waterproof function of the structure is further improved. For the screw holes, the PVC pipes in the wall are first removed and cleaned with an impact drill, and the residual mortar around the holes is cleaned. The outer holes are expanded into a 20mm deep trumpet shape as much as possible. Water is sprayed on the outer wall with a spray bottle to keep the area around the bolt holes moist. After the expansion cement waterproof mortar is partially poured in from the outside to the inside of the outer wall with an iron trowel, the foaming agent is injected from the inside until it overflows. After solidification, the polyurethane waterproof material is applied with a thickness of 1.5mm and a diameter of 100mm, with the outer wall bolt hole as the center. For the reserved holes on the inner plane of the building, the reserved casing is first removed and roughened with an impact drill. After the pipe is buried, it is sprayed with water with a spray bottle. After the pipe surface is roughened, micro-expanded fine stone concrete (mixed with 3% waterproofing agent) is used to cast the concrete in two steps.

[0048] (3) After filling the 150mm below the window frame with waterproof mortar, inject foaming agent into the periphery of the window frame. During the foaming process, a baffle is used on the outside to ensure the one-time molding effect of the outer surface of the foaming agent. Then, cement waterproof mortar is used for overall sealing, and JS waterproof coating is applied around the outer periphery of the window frame.

[0049] Construction inspection methods

[0050] (1) Concrete water seepage resistance test: First, prepare concrete materials and mix concrete according to the designed proportion; second, pour concrete into the mold, compact and vibrate it thoroughly; third, maintain the concrete specimen; fourth, place the specimen at room temperature of 20℃ and prepare it before the test; fifth, stick a rubber film on the concrete specimen and apply a waterproofing agent; sixth, place the concrete specimen in the Rockwell permeameter laboratory, apply a fixed pressure difference, and measure the concrete penetration within a certain period of time; seventh, record the penetration amount and time, and calculate the concrete water seepage resistance index, adjust the concrete material mix ratio according to the test data, and effectively improve the self-waterproofing ability of the concrete structure.

[0051] (2) Water storage test: This test is carried out after the structure is completed and before the waterproof material is applied. The test requires that the roof, bathroom, balcony and other places are filled with water, and the water volume must be sufficient. The water storage depth of the self-waterproofing test is 30 mm, and the water storage time is 24 hours. During this period, it is observed several times for leakage. If there is no leakage, it is qualified. If there is a leakage point, necessary measures should be taken in time. The self-waterproofing of the structure is intended to solve the problem of short waterproofing time of waterproof materials and reduce the subsequent maintenance costs.

[0052] Step 4: Collect data on site and conduct analysis. Analyze the influencing factors by collecting data on site and making statistical tables of quality defect items. Then analyze the reasons for the occurrence of such results, and finally formulate and implement countermeasures.

[0053] Step 5: Construction optimization methods: First, strictly control the mix ratio of concrete materials to ensure that the cement ratio meets the design requirements. It is necessary to control the strength grade of cement, the grading grade of sand and gravel, etc.

[0054] Second, pour in the order of pouring, and vibrate in time to prevent honeycomb and voids in the later stage. During pouring, arrange 1-2 reinforcement workers to adjust the steel bars that are deformed by being stepped on at any time, especially the temperature reinforcement on the slab surface. Do not add water during the concrete pouring process, and do not disturb it after initial setting.

[0055] The third is to strengthen concrete curing. Natural curing should be started before the final setting of the concrete (usually within 8 to 12 hours after the concrete is poured). People are allowed to walk on it only after the compressive strength reaches 5MPa. For cracks on concrete slabs or walls, if the cracks are very wide, a 10mm wide and 10-15mm deep groove should be chiseled along the crack position first. After cleaning, apply a layer of treatment agent, and then fill in synthetic polymer sealing materials and apply polymer cement mortar on the surface. If the cracks are small, epoxy resin can be injected into the cracks to seal them. Example 2

[0056] In step three, when pouring concrete, the free fall height of concrete falling from the discharge port shall not exceed 2m to prevent segregation of falling concrete. Before pouring, the bottom should be filled with 3cm thick cement mortar with the same concrete mix ratio to prevent "root rot". The vibrator should be inserted quickly and pulled out slowly, and the insertion points should be evenly arranged and moved point by point in sequence without omission to ensure uniform vibration. The moving spacing should not be greater than 1.5 times the vibration action radius (generally 20-30cm). When vibrating the upper layer, 5-10cm should be inserted into the lower layer to ensure a firm bond between the two layers of concrete. After pouring concrete, a secondary surface treatment should be performed to reduce surface cracks. The screw holes, reserved openings and window frames should be sealed, and the outermost side of the screw holes should be coated with polyurethane waterproof material. The reserved casing should be removed and roughened with an impact drill at the reserved opening, and then sprayed with water using a spray bottle to moisten it, and then a higher grade of micro-expanding fine stone concrete (mixed with 3% waterproofing agent) should be used for pouring. The 150mm below the window frame is sealed with waterproof mortar, and the rest of the seams are sealed with foaming agent, then sealed with waterproof mortar and painted with 100mm wide JS waterproof coating. By monitoring the self-waterproofing test process of the structure, the weak points of leakage are found, and the situations that occur are studied in depth to form a written report. The focus of the later construction is to improve the self-waterproofing ability of the structure and further solve the problems of short waterproofing time of waterproof materials and excessive maintenance costs in the later stage.

[0057] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and all variations coming within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A method for preventing cracks and leakage in reinforced concrete roofs, wherein the construction method comprises: investigation and research → construction plan formulation → construction and observation testing → numerical analysis → construction optimization, and is characterized by: It includes the following five steps: Step 1: Through the investigation of the current situation of crack and leakage prevention in the current building construction project, information research, collection and collation of relevant data, preparation of corresponding technical plans, formulation of safeguard measures, through research group discussion and on-site implementation, modification of relevant technical measures according to the demonstration results; (1) Research on structural self-waterproofing test methods; (2) Research on one-step molding technology for bathroom, kitchen and balcony anti-slope pouring; (3) Study on the key points of sealing the screw holes in the exterior walls and the bottoms of windows, doors and window frames; (4) Research on the post-processing process of reserved casing; Step 2: The project department will carry out implementation organization design and plan preparation based on the confirmed technical data, and formulate staffing, material and equipment plans and schedule; Step 3: Track and control the entire operation process to ensure the quality of the operation; Construction plan (1) After the slab reinforcement is tied, place a 3*100mm water-stop flat iron, which is 50mm higher than the slab elevation. When the carpenters lower the slab and "hang the formwork", the bathroom's anti-slope is positioned and supported at the same time. The accuracy of the position and elevation must be ensured during positioning. When pouring concrete, pour the bathroom and kitchen immediately after pouring the wall columns, and then pour the other slab surfaces. Pour the anti-slope of the bathroom and kitchen before the concrete begins to set. During the pouring process, the vibration interval needs to be shortened accordingly. The duration of the tamping should be such that the concrete surface produces floating slurry, no bubbles, and no sinking. The vibrator insertion points are evenly arranged in a plum blossom shape to ensure that the lower part of the anti-slope is dense. (2) By sealing the screw holes on the outer wall and the reserved holes on the inner plane of the building, the waterproof function of the structure is further improved. For the screw holes, the PVC pipes in the wall are first removed and cleaned with an impact drill, and the residual mortar around the holes is cleaned. The outer holes are expanded into a 20mm deep trumpet shape, and water is sprayed on the outer wall with a spray bottle to keep the area around the bolt holes moist. After the expansion cement waterproof mortar is partially poured into the outer wall from the outside to the inside with an iron trowel, the foaming agent is injected from the inside until it overflows. After solidification, the polyurethane waterproof material is applied with a thickness of 1.5mm and a diameter of 100mm around the outer wall bolt hole. For the reserved holes on the inner plane of the building, the reserved casing is first removed and roughened with an impact drill. After the pipe is buried, it is sprayed with water with a spray bottle. After the pipe surface is roughened, micro-expanded fine stone concrete mixed with 3% waterproofing agent is poured and formed in two times. (3) After filling the 150mm below the window frame with waterproof mortar, inject foaming agent into the window frame. During the foaming process, a baffle is used on the outside to ensure the one-time molding effect of the outer surface of the foaming agent. Then, cement waterproof mortar is used for overall sealing, and JS waterproof coating is applied around the outer perimeter of the window frame. Construction inspection methods (1) Concrete water seepage resistance test: First, prepare concrete materials and mix concrete according to the designed proportion; second, pour concrete into the mold, compact and vibrate it thoroughly; third, cure the concrete specimen; fourth, place the specimen at room temperature of 20℃ and prepare it before the test; fifth, stick a rubber film on the concrete specimen and apply a waterproofing agent; sixth, place the concrete specimen in the Rockwell permeameter laboratory, apply a fixed pressure difference, and measure the concrete permeability within a certain period of time; seventh, record the permeability and time, and calculate the concrete's water seepage resistance index; (2) Water storage test: This test is carried out after the structure is completed and before the waterproof material is applied. The test requires that the roof, bathroom and balcony are filled with water, and the water volume must be sufficient. The water storage depth of the waterproof test is 30 mm, and the water storage time is 24 hours. During this period, the water leakage is observed several times. If there is no leakage, it is qualified. If there is a leakage point, necessary measures should be taken in time. Step 4: Collect data on site and conduct analysis. Analyze the influencing factors by collecting data on site and making statistical tables of quality defects. Then analyze the reasons for the occurrence of such results, and finally formulate and implement countermeasures. Step 5: Construction optimization methods: First, strictly control the mix ratio of concrete materials to ensure that the cement ratio meets the design requirements. It is necessary to control the strength grade of cement and the grading grade of sand and gravel; Second, pour in the order of pouring, and vibrate in time to prevent honeycomb and voids in the later stage. During pouring, arrange 1-2 reinforcement workers to adjust the steel bars that are deformed by being stepped on at any time, especially the temperature reinforcement on the slab surface. Do not add water during the concrete pouring process, and do not disturb it after initial setting. The third is to strengthen concrete curing. Natural curing should be started before the final setting of the concrete, usually within 8-12 hours after the concrete pouring is completed. People are allowed to walk on it after the compressive strength reaches 5MPa. For cracks on concrete slabs or walls, if the cracks are very wide, first chisel a 10mm wide and 10-15mm deep groove along the crack position, clean it, apply a layer of treatment agent, and then fill it with synthetic polymer sealing material, and apply polymer cement mortar on the surface; if the cracks are small, epoxy resin can be injected into the cracks to seal the cracks.

2. A reinforced concrete roof crack prevention method according to claim 1, characterized in that: When pouring concrete in the third step, the free fall height of the concrete from the discharge port shall not exceed 2m to prevent the falling concrete from segregating. Before pouring, the bottom should be filled with 3cm thick cement mortar with the same concrete mix ratio to prevent "root rot". At the same time, the vibrator should be inserted quickly and pulled out slowly, and the insertion points should be evenly arranged and moved point by point in sequence without omission to ensure uniform vibration. The moving spacing should not be greater than 1.5 times the vibration action radius, generally 20-30cm. When vibrating the upper layer, it should be inserted into the lower layer 5-10cm deep to ensure that the two layers of concrete are firmly combined. After the concrete is poured, a secondary surface treatment is performed to reduce surface cracks.

3. A reinforced concrete roof crack prevention method according to claim 1, characterized in that: In the step three, before sealing the screw holes, reserved openings and the surrounding area of the window frames, it is necessary to apply polyurethane waterproof material to the outermost side of the screw holes; use an impact drill to remove the reserved casing and chisel and clean it, then use a spray bottle to spray water to moisten it, and then use a higher grade of micro-expanded fine stone concrete mixed with 3% waterproofing agent for pouring; use waterproof mortar to seal 150mm below the window frame, and use foaming agent to fill the seams in the remaining parts, then use waterproof mortar to seal the seams and apply 100mm wide JS waterproof coating on the outside.

4. A reinforced concrete roof crack prevention method according to claim 1, characterized in that: By monitoring the structural self-waterproofing test process, we can identify weak points of leakage, conduct in-depth research on the situations that arise, and form a written report. We will focus on monitoring the subsequent construction to improve the self-waterproofing capabilities of the structure and further solve the problems of short waterproofing time of waterproof materials and excessive subsequent maintenance costs.

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