Construction techniques for repairing the exterior walls of old buildings

Abstract

This invention relates to a construction process for repairing the exterior walls of old buildings. This process is suitable for repairing exterior walls of old buildings with peeling or hollow areas less than four square meters, and includes the following steps: S1: Determine the area of ​​the hollow or peeling exterior wall using one or more of the following methods: a) ruler measurement; b) infrared imaging; S2: Determine the smallest rectangle based on the shape of the hollow area determined in S1, and extend each side of this smallest rectangle outwards by 5-15 cm as the repair area; S3: Remove the exterior wall in the repair area down to the brick base layer, and grind away any remaining adhesions in areas that cannot be completely removed; S4: Apply cement mortar, partially embedding a vertical sheet-like grid into the mortar surface layer, maintaining the same thickness as the original building; S5: Apply an interface agent to fill the grid; S6: Apply exterior wall paint or putty. Through the above setup, the connection strength of the peeling area can be increased, resulting in better repair effects and preventing further peeling.

Description

Technical Field

[0001] This invention relates to the field of exterior wall repair technology, and in particular to a construction process for repairing the exterior walls of old buildings. Background Technology

[0002] Due to factors such as worker error or material defects, hollow spots often appear on walls after a period of time, especially noticeable in older buildings. Accompanying these spots are wall cracks, and over time, the plaster will peel off, affecting aesthetics and posing a safety hazard to the elderly and children. Traditional repair methods involve cutting away the peeling cement mortar and putty, repainting with cement mortar, and then applying putty and paint on top. However, this method often results in low bonding strength, sometimes even lower than the original cement mortar. The repaired exterior wall is prone to recurring hollow spots after a period of use. Furthermore, current wall crack repair methods typically involve workers manually scraping off the putty and paint, increasing subsequent cleaning work and increasing the risk of inhaling dust, which can be harmful. Spraying or wetting the wall can also introduce debris that contaminates the underlying wall surface. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a construction process for repairing the exterior walls of old buildings, which can effectively solve these problems.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] A construction process for repairing the exterior walls of old buildings, applicable to repairing exterior walls of old buildings with peeling or hollow areas less than four square meters, includes the following steps:

[0006] S1: Determine the area of ​​hollow or peeling exterior walls using one or more of the following methods: a) ruler measurement; b) infrared imaging.

[0007] S2: Determine the minimum rectangle based on the hollow shape determined by S1, and use a rectangle that extends 5-15cm outward on each side as the repair area.

[0008] S3: Remove the exterior wall of the repair area down to the brick base layer, and grind away any remaining attachments in areas that cannot be completely removed.

[0009] S4: Apply cement mortar, partially embedding the vertical sheet mesh into the mortar surface layer, keeping the cement mortar coating thickness the same as the original building;

[0010] S5: Apply interface agent to fill the grid;

[0011] S6: Apply exterior wall paint or putty to restore the exterior wall to its original condition.

[0012] To achieve the above technical solution, the area of ​​hollow and detached exterior walls must first be measured using one or more of the following methods: a) Observe the hollow and detached areas and determine their dimensions using a ruler; b) Scan the exterior walls with an infrared thermal imager to detect the temperature field distribution, representing the surface temperature field in a two-dimensional thermal image and calculating the corresponding hollow dimensions. All damaged, hollow, and detached exterior walls must be removed until the brick-concrete structure is exposed. Generally, the exterior walls of buildings experience periodic temperature changes throughout the day or year due to variations in air temperature or solar radiation. The surface temperature of a building will vary depending on the physical properties of the wall materials, such as specific heat and thermal conductivity, and the surface temperature... Differences in shape and state lead to variations in the temperature field distribution of walls. Infrared thermal imaging uses an infrared thermal imager to quickly scan and detect the temperature field distribution of building exterior walls, presenting the temperature field of the object's surface in the form of a two-dimensional thermal image. Through comprehensive processing and analysis, it can determine whether there are defects. It can perform non-contact scanning of exterior walls, quickly and over large areas, to detect infrared radiation anomalies in exterior wall finishes, thereby achieving rapid determination of the area of ​​hollow or detached exterior wall finishes. When applying exterior wall paint or putty, the color of the paint or putty should be the same as the original exterior wall color. When applying the interface agent, fill the grid and then quickly apply a 0.1-0.3mm layer of interface agent.

[0013] As a preferred embodiment of the present invention, in step S1, based on the infrared measurement results, the exterior facade of the partially questionable area is re-verified using the hammering method to further determine the specific hollow area of ​​the building.

[0014] As a preferred embodiment of the present invention, the wall is sprayed with water to moisten it before applying cement mortar in step S4.

[0015] In a preferred embodiment of the present invention, in step S4, the thickness of the vertical sheet mesh is 2.5-3.5 mm, the thickness of the vertical sheet mesh embedded in the cement mortar is 1.5-2 mm, and the thickness of the vertical sheet mesh protruding is 1-1.5 mm.

[0016] As a preferred embodiment of the present invention, the interface agent selected in step S5 is an emulsion-type interface agent.

[0017] To achieve the above technical solution, emulsion-type interface agents are used to treat the surfaces of concrete, aerated concrete, sand-lime bricks, and fly ash bricks, solving the problem that the interfaces are not easy to bond due to the high water absorption or smoothness of these surfaces, resulting in hollow plaster layers, cracking, and peeling. This can greatly enhance the bonding force between new and old concrete, as well as between concrete and plaster mortar.

[0018] As a preferred embodiment of the present invention, in step S3, the following scraping and grinding device is used, the scraping and grinding device includes: a base, the base is provided with a two-axis servo drive assembly, and the power output end of the two-axis servo drive assembly is connected to a mobile platform;

[0019] The lifting mechanism includes: a lifting assembly disposed on the mobile platform, a lifting platform sleeved on the piston rod of the lifting assembly, a rotating rod rotatably connected to one end of the lifting assembly, a mounting base disposed at the end of the rotating rod, and a scraper or grinding component detachably disposed on the mounting base.

[0020] An elastic component is disposed on the lifting platform and elastically connected to the other end of the rotating rod;

[0021] Cleaning components are used to prevent dust during scraping and to wet the wall before applying mortar;

[0022] Sealing components are used to shield cleaning water from contaminating the walls.

[0023] To achieve the above technical solution, the base platform is lowered to the exterior wall requiring repair via cables. Then, the lifting assembly is activated to move the lifting platform and scraper to the designated area. A two-axis servo drive component drives the moving platform so that the scraper contacts the exterior wall. The lifting assembly is then activated downwards to scrape away debris from the exterior wall. Simultaneously, a cleaning component is activated to spray the scraped area to reduce dust and prevent overheating of the scraper. The spray also wets the wall, ensuring a more stable bond between the subsequent mortar and the wall. During scraping, an elastic component provides elastic force to one end of the rotating rod, allowing the scraper to move flexibly while maintaining scraping force, preventing it from getting stuck in the brick joints. A water stream is sprayed onto the wall during scraping, carrying scraped debris downwards. After the surface dries, the debris is removed. Debris can dry and adhere to the wall, making it difficult to clean. A sealing component is used to create a seal with the bottom of the wall in the scraping area, directing water away from the wall and keeping the surface clean. Then, a two-axis servo drive component moves the scraper longitudinally to continue scraping. After scraping, the scraper on the mounting base is replaced with a grinding component. Water continues to be sprayed during grinding. The grinding component moves in the same way as the scraper, using a longitudinal grinding method. This device eliminates the need for personnel to stand on the base during scraping and grinding, preventing dust hazards to workers and reducing the risk of working at heights. The two-axis servo drive component, grinding component, and lifting component can all be remotely controlled via wired or wireless means; specific control methods are existing technology and will not be elaborated upon.

[0024] As a preferred embodiment of the present invention, the elastic component includes: a sleeve disposed on the moving platform, a positioning rod slidably connected to the sleeve and fixedly passing through the lifting platform, a first spring sleeved on the positioning rod and with one end abutting against the lifting platform, a floating sleeve sleeved at the end of the positioning rod and abutting against the other end of the first spring, and a rotating seat disposed on the floating sleeve and rotatably connected to the rotating rod.

[0025] To achieve the above technical solution, when the scraper gets stuck in the brick joint, the reaction force provided by the brick joint causes the mounting base to rise, thereby pressing down the rotating base at the other end of the rotating rod. The rotating base compresses the first spring through the floating sleeve, causing the rotating rod to rotate around the end of the lifting assembly. This allows the mounting base and the scraper to have an upward arc movement, thus achieving horizontal displacement away from the brick joint of the wall. This prevents the scraper from getting stuck in the brick joint and being unable to continue downward. At the same time, the elastic component can absorb vibration and impact energy, preventing the scraper from being damaged by rigid collisions and extending the service life of the scraper.

[0026] In a preferred embodiment of the present invention, the cleaning assembly includes a pump disposed on the side of the lifting platform near the scraper, and a nozzle disposed on the water outlet pipe of the pump and facing the bottom of the scraper. The grinding assembly includes a detachable servo motor disposed on the mounting base and a grinding wheel connected to the power output shaft of the servo motor. An adjusting rod is disposed on the side of the lifting platform away from the pump. A counterweight ring is slidably sleeved on the adjusting rod. A pin is movably inserted through the counterweight ring. The adjusting rod has a plurality of slots adapted to the pin.

[0027] To achieve the above technical solution, the pump is connected to an external water pipe to pump water from the nozzle into the bottom of the scraper for spraying. The scraper is disassembled by bolts, and then a servo motor is installed and fixed by bolts. The servo motor drives the grinding wheel for grinding. By adjusting the rod, the counterweight ring is moved left and right. The pin is inserted into the slot to fix the counterweight ring, so that the weight of the lifting platform is similar on both sides of the sleeve and the lifting component, thereby avoiding tilting and improving the rationality of the structure.

[0028] As a preferred embodiment of the present invention, the sealing assembly includes: a plurality of elastic grooves formed in the moving platform, a second spring disposed inside the elastic grooves, a slide rod slidably connected to the elastic grooves and abutting against the second springs, limiting grooves formed on both sides of the elastic grooves, limiting blocks connected to the slide rods and adapted to the limiting grooves, and a sealing strip disposed at the end of the slide rods, the end of the sealing strips being disposed on two sets of adhesive strips with gaps, and the bottom of the sealing strips being disposed on a water baffle plate inclined downward toward the base.

[0029] To achieve the above technical solution, the second spring and slide bar ensure that the sealing strip is always in contact with the wall. The bonding strip further increases the sealing between the sealing strip and the wall. The water baffle directs the water flow away from the wall.

[0030] As a preferred embodiment of the present invention, a pad is provided on the side of the base near the mounting seat, and a lifting lug is provided on the top of the side of the base away from the mounting seat.

[0031] To achieve the above technical solution, the pads are made of rubber, which can prevent the base from damaging the wall. The lifting lugs are anchored on the roof with cables, and one side of the base is abutted against the wall by the pads.

[0032] In summary, the present invention has the following beneficial effects:

[0033] This invention provides a construction process for repairing the exterior walls of old buildings. It accurately measures the area of ​​hollow and detached areas, and rationally sets up the repair area. While reducing the construction area, it ensures connection strength. A grid is embedded within the cement mortar, allowing the grid to adhere to the wall. An interface agent is applied to the outside of the grid, effectively adhering the interface agent to the cement mortar, greatly improving its adhesion. The interface agent then bonds the applied paint or putty, effectively preventing the paint or putty from detaching or becoming hollow. The grid can... The system balances the stress on the repair area, improving tensile and tear strength. Its scraping and grinding device thoroughly cleans the wall surface. An elastic component prevents the scraper from getting stuck in the brickwork. A sealing component creates a seal with the bottom of the scraped area, directing water away from the wall to keep the surface clean. A cleaning component sprays the scraped area to reduce dust and prevent overheating. The spray also wets the wall, ensuring a more stable bond between the subsequent mortar and the wall. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of the present invention.

[0036] Figure 2 For the present invention Figure 1 Enlarged view of point A in the middle.

[0037] Figure 3 This is a schematic diagram of the grinding component of the present invention.

[0038] Figure 4 This is a schematic diagram of the vertical sheet-like mesh structure of the present invention.

[0039] The numbers and letters in the diagram represent the names of the corresponding components:

[0040] 1. Base; 2. Two-axis servo drive assembly; 3. Moving platform; 4. Lifting assembly; 5. Pump; 6. Nozzle; 7. Sealing strip; 8. Adhesive strip; 9. Water baffle; 10. Pad; 11. Sleeve; 12. Lifting platform; 13. Adjusting rod; 14. Counterweight ring; 15. Pin; 16. First spring; 17. Rotating rod; 18. Floating sleeve; 19. Positioning rod; 20. Rotating seat; 21. Mounting seat; 22. Scraper; 23. Lifting lug; 24. Grinding wheel; 25. Elastic groove; 26. Limiting groove; 27. Limiting block; 28. Slide rod; 29. ​​Second spring; 30. Servo motor; 31. Vertical sheet mesh. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example

[0043] like Figures 1 to 3 As shown, a construction process for repairing the exterior walls of old buildings is described. This process is suitable for repairing exterior walls of old buildings with peeling or hollow areas of less than four square meters, and includes the following steps:

[0044] S1: Determine the area of ​​hollow and detached exterior walls; determine the area by one or more of the following methods: a) observe the hollow and detached areas and determine the size of the hollow and detached areas by measuring with a ruler; b) scan and detect the temperature field distribution of the building's exterior walls with an infrared thermal imager, represent the temperature field of the object's surface in the form of a two-dimensional thermal image, and calculate the corresponding hollow size.

[0045] S2: Determine the minimum rectangle based on the hollow shape determined by S1, and use a rectangle that extends 5-15cm outward on each side as the repair area.

[0046] S3: Remove the exterior wall of the repair area down to the brick base layer, and grind away any remaining attachments in areas that cannot be completely removed.

[0047] S4: Apply cement mortar, partially embedding the vertical sheet mesh into the mortar surface layer, keeping the cement mortar coating thickness the same as the original building;

[0048] S5: Apply interface agent to fill the grid;

[0049] S6: Apply exterior wall paint or putty to restore the exterior wall to its original condition.

[0050] First, determine the area of ​​hollow and detached exterior walls using one or more of the following methods: a) Observe the hollow and detached areas and determine their dimensions using a ruler; b) Scan the exterior wall with an infrared thermal imager to detect the temperature field distribution, representing the surface temperature field in a two-dimensional thermal image and calculating the corresponding hollow dimensions. Remove all damaged, hollow, and detached exterior walls until the brick-concrete structure is exposed. Generally, the exterior walls of buildings experience periodic temperature changes throughout the day or year due to variations in air temperature or solar radiation. The surface temperature of a building will vary depending on the physical properties of the wall materials (specific heat and thermal conductivity), surface morphology, and condition, thus affecting the wall temperature. Differences in temperature field distribution can be observed. Infrared thermal imaging uses an infrared thermal imager to quickly scan and detect the temperature field distribution of a building's exterior wall, presenting the temperature field of the object's surface in the form of a two-dimensional thermal image. Through comprehensive processing and analysis, it can determine whether there are defects. It can perform non-contact scanning of the exterior wall, quickly and over a large area, to detect infrared radiation anomalies in the exterior wall finish, thereby achieving rapid determination of the area of ​​hollow or detached exterior wall finishes. When applying exterior wall paint or putty, the color of the paint or putty should be the same as the original exterior wall color. When applying the interface agent, fill the grid and then quickly apply a 0.1-0.3mm layer of interface agent.

[0051] Furthermore, in step S1, based on the infrared measurement results, the exterior facade of the areas with doubts is re-verified using the hammering method to further determine the specific hollow area of ​​the building. In step S4, before applying cement mortar, the wall is sprayed with water to moisten it. In step S4, the thickness of the vertical sheet mesh is 2.5-3.5mm, the thickness of the vertical sheet mesh embedded in the cement mortar is 1.5-2mm, and 2mm is selected in this embodiment. The thickness of the vertical sheet mesh exposed is 1-1.5mm, and 1mm is selected in this embodiment. In step S5, the interface agent is selected as an emulsion-type interface agent. The emulsion-type interface agent is used to treat the surfaces of concrete, aerated concrete, sand-lime bricks, and fly ash bricks, etc., to solve the problem that the interface is not easy to bond due to the high water absorption or smoothness of these surfaces, resulting in hollow, cracked, and peeling plaster layers. It can greatly enhance the adhesion between new and old concrete and between concrete and plaster mortar.

[0052] Specifically, in step S3, the following scraping and grinding device is used, which includes: a base 1, on which a two-axis servo drive assembly 2 is installed, and the power output end of the two-axis servo drive assembly 2 is connected to a moving platform 3; a lifting mechanism, including: a lifting assembly 4 installed on the moving platform 3, a lifting platform 12 sleeved on the piston rod of the lifting assembly 4, a rotating rod 17 rotatably connected to one end of the lifting assembly 4, a mounting base 21 installed at the end of the rotating rod 17, and a detachable scraper 22 or grinding component installed on the mounting base 21; an elastic component installed on the lifting platform 12 and elastically connected to the other end of the rotating rod 17; a cleaning component for dust prevention during scraping and wall wetting before applying mortar; and a sealing component for shielding the cleaning water to prevent contamination of the wall. The base 1 is lowered to the exterior wall to be repaired via a cable, and then the lifting assembly 4 is activated to move the lifting platform 12 and the scraper 22 to the scraping position. In a defined area, the two-axis servo drive assembly 2 drives the moving platform 3 to bring the scraper 22 against the exterior wall. The lifting assembly 4 then moves downwards to scrape the exterior wall using the scraper 22. Simultaneously, a cleaning assembly is activated to spray the scraped area with water to reduce dust and prevent overheating of the scraper 22. The spray also wets the wall, ensuring a more stable bond between the mortar and the wall. During scraping, an elastic component provides elastic force to one end of the rotating rod 17, allowing the scraper 22 to move flexibly while maintaining scraping force, preventing it from getting stuck in the brick joints. Water is sprayed onto the wall during scraping, carrying scraped debris downwards. After drying on the surface, the debris hardens and becomes difficult to clean. A sealing assembly forms a seal with the bottom of the scraped area, directing the water away from the wall and keeping the surface clean. The two-axis servo drive assembly 2 then... The scraper 22 is rotated longitudinally to continue scraping. After scraping is completed, the scraper 22 on the mounting base 21 is replaced with a grinding component. Water is sprayed during grinding. The grinding component moves in the same way as the scraper 22, which is a longitudinal row-changing grinding. This device does not require personnel to stand on the base 1 during scraping and grinding, which can avoid the harm of scraping and grinding dust to construction personnel and reduce the risk of manual high-altitude operations. The two-axis servo drive component 2, the grinding component, and the lifting component 4 can all be remotely controlled by wired or wireless means. The specific control method is existing technology and will not be described in detail.

[0053] The elastic component includes: a sleeve 11 disposed on the moving platform 3; a positioning rod 19 slidably connected to the sleeve 11 and fixedly passing through the lifting platform 12; a first spring 16 sleeved on the positioning rod 19 and with one end abutting against the lifting platform 12; and a sleeved on the end of the positioning rod 19 and abutting against the first spring 16. The other end of the floating sleeve 18 and the rotating seat 20, which is set on the floating sleeve 18 and rotatably connected to the rotating rod 17, when the scraper 22 is stuck in the brick joint, the reaction force provided by the brick joint causes the mounting seat 21 to rise, thereby pressing down the rotating seat 20 at the other end of the rotating rod 17. The rotating seat 20 compresses the first spring 16 through the floating sleeve 18, causing the rotating rod 17 to rotate around the end of the lifting assembly 4, thereby causing the mounting seat 21 and the scraper 22 to have an upward arc movement, thereby having a horizontal displacement away from the brick joint of the wall, which can prevent the scraper 22 from getting stuck in the brick joint and unable to continue downward. At the same time, the elastic component can absorb vibration and impact energy, prevent the scraper 22 from being damaged by rigid collision, and extend the service life of the scraper 22. The cleaning assembly includes a pump 5 set on the side of the lifting platform 12 near the scraper 22 and a nozzle 6 set on the water outlet pipe of the pump 5 and facing the bottom of the scraper 22.

[0054] The grinding assembly includes: a detachable servo motor 30 mounted on the mounting base 21, and a grinding wheel 24 connected to the power output shaft of the servo motor 30. An adjusting rod 13 is provided on the side of the lifting platform 12 away from the pump 5. A counterweight ring 14 is slidably sleeved on the adjusting rod 13. A pin 15 is movably inserted into the counterweight ring 14. The adjusting rod 13 has several slots that fit the pins 15. The pump 5 is connected to an external water pipe and pumps water from the nozzle 6 into the bottom of the scraper 22 for spraying. The scraper 22 is removed by bolts, and the servo motor 30 is then installed and fixed by bolts. The servo motor 30 drives the grinding wheel 24 for grinding. By adjusting the adjusting rod 13, the counterweight ring 14 is moved left and right. The pin 15 is inserted into the slot to fix the counterweight ring 14, so that the weight of the lifting platform 12 is similar on both sides of the base 11 and the lifting assembly 4, thereby avoiding tilting and improving the structural rationality.

[0055] The sealing assembly includes: several elastic grooves 25 formed in the movable platform 3; a second spring 29 disposed inside the elastic groove 25; a slide rod 28 slidably connected to the elastic groove 25 and abutting against the second spring 29; limiting grooves 26 formed on both sides of the elastic groove 25; a limiting block 27 connected to the slide rod 28 and adapted to the limiting groove 26; and a sealing strip 7 disposed at the end of the slide rod 28. The end of the sealing strip 7 is provided with two sets of adhesive strips 8 with gaps. The bottom of the sealing strip 7 is provided with a water baffle 9 inclined downward toward the base 1. Through the second spring 29 and the slide rod 28, the sealing strip 7 can always adhere to the wall. Through the adhesive strips 8, the sealing degree between the sealing strip 7 and the wall is further increased. Through the water baffle 9, the water flow can be guided away from the wall.

[0056] Furthermore, a pad 10 is provided on the side of the base 1 closest to the mounting base 21, and a lifting lug 23 is provided on the top of the side of the base 1 away from the mounting base 21. The pad 10 is made of rubber, which can prevent the base 1 from damaging the wall. The lifting lug 23 is anchored on the roof by a cable. One side of the base 1 is abutted against the wall by the pad 10.

[0057] In application, the hollow area is delineated using a ruler measurement method, infrared imaging method, and hammering method. An additional 5-15cm is then added as the adsorption area. A mesh is embedded within the cement mortar, allowing it to adhere to the wall. An interface agent is applied to the outside of the mesh, effectively adhering the agent to the cement mortar and significantly improving its adhesion. The interface agent then bonds the applied paint or putty, effectively preventing it from peeling off or causing hollow areas. The mesh balances the stress on the repaired area, improving... The tensile and tear resistance is excellent. The set scraping and grinding device can thoroughly clean the wall. The set elastic component can prevent the scraper 22 from getting stuck in the brick joints of the wall. The set sealing component can form a seal with the bottom of the wall in the scraped area and direct water flow away from the wall to keep the wall clean. The set cleaning component can spray dust on the scraped area of ​​the scraper 22 and prevent the scraper 22 from overheating. The spray can also wet the wall, making the subsequent mortar bonding with the wall more stable.

[0058] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A construction process for repairing an old building outer wall, characterized in that, The process is suitable for repairing the old building outer wall falling off, the hollow area of less than four square meters of outer wall, including the following steps: S1: measuring the area of the hollowing and falling off outer wall, by one or more of the following methods: a, ruler measurement method; b, infrared imaging method; S2: determining the minimum rectangle according to the shape of the hollowing determined by S1, and expanding the rectangle by 5-15 cm on each side as the repair area based on the minimum rectangle; S3: the outer wall of the repair area is removed to the wall brick base layer, and the remaining attachment of the area that cannot be removed completely is polished; the following removal and polishing device is adopted: the removal and polishing device comprises a base, a two-axis servo drive assembly is arranged on the base, a moving platform is connected to the power output end of the two-axis servo drive assembly; a lifting mechanism, comprising a lifting assembly arranged on the moving platform, a lifting platform sleeved on the lifting assembly, a rotating rod rotatably connected to one end of the lifting assembly, a mounting seat arranged on the end of the rotating rod, a scraper or a polishing piece detachably arranged on the mounting seat; an elastic assembly arranged on the lifting platform and elastically connected to the other end of the rotating rod; a cleaning assembly for dust removal during scraping and wall soaking before mortar brushing; a sealing assembly for shielding the cleaning water to prevent pollution of the wall; The elastic assembly comprises a sleeve seat arranged on the moving platform, a positioning rod slidably connected to the sleeve seat and fixedly penetrating the lifting platform, a first spring sleeved on the positioning rod and abutting against the lifting platform at one end, a floating sleeve sleeved on the end of the positioning rod and abutting against the other end of the first spring, and a rotating seat arranged on the floating sleeve and rotatably connected to the rotating rod; S4: brushing cement mortar, embedding a vertical sheet-shaped grid into the mortar surface layer, and keeping the thickness of the cement mortar brushing the same as the original building; S5: brushing interface agent to fill the grid; S6: brushing the outer wall coating or putty to obtain a repaired complete outer wall.

2. The construction process for repairing the outer wall of an old building according to claim 1, characterized in that; In the S1 step, according to the infrared measurement result, the outer facade of the local suspicious area is re-detected by hammering method for further determination of the specific hollowing area of the house.

3. The construction process for repairing the outer wall of an old building according to claim 1, characterized in that, In the S4 step, the wall is treated by water spraying before brushing the cement mortar.

4. The construction process for repairing the outer wall of an old building according to claim 1, characterized in that, In the S4 step, the thickness of the vertical sheet-shaped grid is 2.5-3.5 mm, the thickness of the vertical sheet-shaped grid embedded in the cement mortar is 1.5-2 mm, and the thickness of the vertical sheet-shaped grid is 1-1.5 mm.

5. The construction process for repairing the outer wall of an old building according to claim 1, characterized in that, The interface agent in the S5 step is selected as an emulsion type interface agent.

6. The construction process for repairing the outer wall of an old building according to claim 1, characterized in that, The cleaning assembly comprises a pump arranged on the lifting platform near the scraper, and a nozzle arranged on the water outlet pipe of the pump and facing the bottom of the scraper, the polishing piece comprises a servo motor detachably arranged on the mounting seat, and a grinding wheel connected to the power output shaft of the servo motor, the side of the lifting platform away from the pump is provided with an adjusting rod, the adjusting rod is slidably sleeved with a counterweight ring, the counterweight ring is movably inserted with a latch, and the adjusting rod is provided with a plurality of insertion slots matched with the latch.

7. The construction process for repairing the outer wall of an old building according to claim 1, characterized in that, The sealing assembly comprises a plurality of elastic grooves formed in the mobile platform, a second spring arranged in the elastic groove, a sliding rod slidingly connected to the elastic groove and abutting against the second spring, a limiting groove formed on both sides of the elastic groove, a limiting block connected to the sliding rod and fitted in the limiting groove, and a sealing strip arranged at the end of the sliding rod. 8.The old building outer wall repairing construction process according to claim 1, characterized in that, The base is provided with a pad on the side close to the mounting seat, and is provided with a lifting lug on the top of the side away from the mounting seat.

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