Building exterior wall maintenance process

Abstract

This invention discloses a building exterior wall repair process, comprising the following steps: S1, removing loose dust and stains from the exterior wall surface; S2, delineating the core area and the outer area, and chiseling away the surface layer of both the core area and the outer area until the concrete structural base is exposed; S3, injecting repair agent into the cracks until the cracks are filled with repair agent, and then continuing to inject repair agent into the core area and the outer area to form a repair agent layer; S4, applying a first layer of cement mortar to the surface of the repair agent layer, laying a layer of fiberglass cloth on the surface of the first layer of cement mortar in the outer area, and laying a layer of wire mesh on the surface of the first layer of cement mortar in the core area; S5, after the cement mortar reaches the standard hardness, applying an interface agent and wall paint in sequence. The exterior wall cracks repaired using this method are less prone to secondary cracking, and the repaired exterior wall's strength and tensile toughness are greatly guaranteed, effectively ensuring the service life of the building exterior wall.

Description

Technical Field

[0001] This invention relates to the field of building exterior wall repair. More specifically, this invention relates to a building exterior wall repair process. Background Technology

[0002] Prolonged exposure to wind and sun, as well as uneven settlement of buildings, can easily cause cracks in building exterior walls. Settlement caused by ground conditions often results in larger cracks, which can lead to leaks, structural instability, and a host of other problems. Current methods for repairing building exterior walls typically involve using cement mixed with adhesive to patch the cracks. However, this method has a drawback: cracks are prone to recurrence, and the protective effect is not ideal. Summary of the Invention

[0003] To achieve these and other advantages according to the present invention, a preferred embodiment of the present invention provides a building exterior wall repair process, comprising the following steps:

[0004] S1. Locate the exterior wall where the crack is located and remove the loose dust and stains from the surface of the exterior wall;

[0005] S2. Mark and delineate the area 30-40cm away from the crack as the core area, and extend the core area outward by 40-50cm to form the outer area, with the outer area enclosing the core area. Remove the surface layer of both the core area and the outer area until the concrete structure base is exposed.

[0006] S3. Inject repair agent into the crack until the entire crack is filled with repair agent, and then continue to inject repair agent into the core area and the outer area until a repair agent layer with a thickness of 3-5mm is formed on the surface of the core area and the outer area.

[0007] S4. Apply the first layer of cement mortar to the surface of the repair agent layer. Lay a layer of fiberglass cloth on the surface of the first layer of cement mortar in the outer area. Lay a layer of wire mesh on the surface of the first layer of cement mortar in the core area. The wire mesh and fiberglass cloth partially overlap in the thickness direction. After the hardness of the first layer of cement mortar reaches half of the standard hardness, continue to apply the second layer of cement mortar on the surface of the first layer of cement mortar, fiberglass cloth, and wire mesh. The fiberglass cloth and wire mesh are located at the interface between the first layer of cement mortar and the second layer of cement mortar.

[0008] S5. After the first and second layers of cement mortar have reached the standard hardness, apply the interface agent and wall paint to the surface of the cement mortar in sequence until the surface is flush with the original surface of the exterior wall.

[0009] More preferably, the raw materials used in the repair agent include the following components in parts by weight:

[0010] 50-60 parts of sulfoaluminate cement, 8-20 parts of silica sol, 5-8 parts of modified bauxite, 4-7 parts of graphite powder, 2-4 parts of starch ether, and 1-3 parts of cellulose.

[0011] More preferably, the modified bauxite is prepared by the following steps:

[0012] The bauxite was calcined at 600-700℃ for 3 hours. The calcined bauxite was then added to a 20-30% phosphite solution at a mass ratio of 1:5 and heated to 70-80℃ for 4 hours to obtain modified bauxite.

[0013] After modification, bauxite can improve the uniformity and workability of the repair agent.

[0014] More preferably, in S4, the fiberglass cloth is divided into two layers, and the two adjacent layers of fiberglass cloth are overlapped, with the overlapping parts of the two layers being closely connected.

[0015] More preferably, two crack-stopping grooves perpendicular to the crack end face are chiseled at both ends of the crack along its length. The crack-stopping grooves have a V-shaped cross-section and are located within the core area. The repair agent is injected into the crack-stopping grooves.

[0016] More preferably, the cement mortar contains glass fiber, the amount of glass fiber being 1% of the mass of the cement mortar, and the diameter of the glass fiber being controlled at 4-5 mm and the length being controlled at 20-23 mm.

[0017] By controlling the diameter, length, and amount of glass fiber within a suitable range, the reinforcing effect of glass fiber on cement can be improved, while avoiding the agglomeration caused by excessively long glass fibers, which would lead to a decrease in the strength of cement mortar.

[0018] More preferably, the glass fiber is surface-polished before use.

[0019] Even better, the fiberglass cloth portion enters the core area, while the steel wire mesh portion enters the outer area, achieving high-strength coverage of the core area by the fiberglass cloth and high-toughness coverage of the outer area by the steel wire mesh.

[0020] Even better, the overlapping areas of the fiberglass cloth and wire mesh are connected with aramid fibers, further improving the overall tensile strength.

[0021] The present invention has at least the following beneficial effects: the cracks in the exterior wall repaired by the building exterior wall repair method of the present invention are not prone to secondary cracking, and the strength and tensile toughness of the repaired exterior wall are greatly guaranteed, effectively ensuring the service life of the building exterior wall.

[0022] (1) Considering that once a large crack appears on a wall, there is usually more than one. There are often many micro-cracks, visible or invisible, around the main crack. Therefore, when repairing the crack with the repair agent, this application also fills the core area within 30-40cm of the crack and the outer area 40-50cm away with the repair agent. A layer of fiberglass cloth is laid on the first layer of cement mortar in the outer area, and a layer of wire mesh is laid on the first layer of cement mortar in the core area. The wire mesh and fiberglass cloth overlap in the thickness direction. This utilizes the high strength of fiberglass and the high toughness of wire mesh, thereby improving the high strength and toughness of cement mortar and preventing cracks from forming later due to thermal expansion and contraction. Moreover, considering that the main crack is more likely to crack later under external influence, a high-toughness wire mesh is laid on the first layer of cement mortar in the core area instead of fiberglass cloth. This arrangement is more reasonable.

[0023] (2) The repair agent used is based on sulfoaluminate cement. The sulfoaluminate cement will have a preliminary filling and compacting effect on the cracks. The high lubricity of graphite and the liquid fluidity of silica sol help the repair agent penetrate into the micropores of the external wall cracks and the micro-cracks of the concrete. The active silica and calcium ions in the silica sol and the cement hydration products integrated into the concrete cracks and micropores undergo a complexation reaction to generate insoluble crystals, which in turn fill the cracks and micropores. As the repair agent further penetrates into the micropores of the cracks and the hydration process continues, the aluminum ions in the bauxite and the calcium ions in the silica sol will undergo a coordination reaction with water to form hydrate ions. These hydrate ions interact with the iron ions in the bauxite and the hydroxide ions in the cement in the repair agent to form a stable insoluble crystal structure, which further increases the blocking and sealing effect on the cracks and ensures a good anti-seepage effect.

[0024] (3) Considering that stress is the main cause of wall cracks, and once cracks are formed, even if they are repaired, the stress may not be completely eliminated. In the above technical solution, by chiseling two crack-stopping grooves perpendicular to the crack end face at both ends along the length of the crack, the stress can be prevented from being transmitted to the outside to a certain extent, reducing the possibility of the crack extending further to the outside.

[0025] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0027] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0028] Application examples

[0029] A preferred embodiment of the present invention provides a building exterior wall repair process, comprising the following steps:

[0030] S1. Locate the exterior wall where the crack is located and remove the loose dust and stains from the surface of the exterior wall;

[0031] S2. Mark the area 40cm away from the crack as the core area, and extend the core area outward by 50cm to form the outer area, with the outer area enclosing the core area. Remove the surface layer of both the core area and the outer area until the concrete structure base is exposed.

[0032] S3. Inject repair agent into the crack until the entire crack is filled with repair agent, and then continue to inject repair agent into the core area and the outer area until a repair agent layer with a thickness of 5mm is formed on the surface of the core area and the outer area; and, at both ends of the crack along the length direction, chisel two crack-stopping grooves perpendicular to the crack end face. The cross-section of the crack-stopping grooves is V-shaped. The crack-stopping grooves are located within the core area, and the repair agent is injected into the crack-stopping grooves.

[0033] The repair agent uses the following raw materials in parts by weight: 50 parts of sulfoaluminate cement, 13 parts of silica sol, 6 parts of modified bauxite, 5 parts of graphite powder, 3 parts of starch ether, and 3 parts of cellulose.

[0034] The modified bauxite is prepared by the following steps: calcining bauxite at 650℃ for 3 hours, adding the calcined bauxite to a 25% phosphite solution at a mass ratio of 1:5, heating to 70℃ and holding for 4 hours to obtain the modified bauxite.

[0035] The cement mortar contains glass fiber, the amount of which is 1% of the mass of the cement mortar, and the diameter of the glass fiber is controlled at 4-5 mm and the length is controlled at 20-23 mm.

[0036] S4. Apply a first layer of cement mortar to the surface of the layer to be repaired. Lay a layer of fiberglass cloth on the surface of the first layer of cement mortar in the outer area, and a layer of wire mesh on the surface of the first layer of cement mortar in the core area. The wire mesh and fiberglass cloth should partially overlap in the thickness direction. After the first layer of cement mortar reaches half of its standard hardness, apply a second layer of cement mortar to the surface of the first layer of cement mortar, fiberglass cloth, and wire mesh. The fiberglass cloth and wire mesh should be located at the interface between the first and second layers of cement mortar. The fiberglass cloth consists of two layers, with adjacent layers overlapping and the overlapping portions closely connected. The fiberglass cloth portion extends into the core area, and the wire mesh portion extends into the outer area. The overlapping areas of the fiberglass cloth and wire mesh are connected using aramid fibers.

[0037] S5. After the first and second layers of cement mortar have reached the standard hardness, apply the interface agent and wall paint to the surface of the cement mortar in sequence until the surface is flush with the original surface of the exterior wall.

[0038] Practical application of the building exterior wall repair method proposed in this invention:

[0039] In August 2021, the above-mentioned repair method was used to repair the cracks in the exterior wall of a residential building in Jinzeyuan Community, Shaoguan City, Guangdong Province. The residential buildings in this community were delivered in 2007, and cracks were found in the exterior wall in 2019. The method of this invention was used to repair the cracks, and after nearly two years of observation, no recurrence of cracking was found.

[0040] Example 1

[0041] The repair agent uses the following raw materials in parts by weight: 50 parts sulfoaluminate cement, 13 parts silica sol, 6 parts modified bauxite, 5 parts graphite powder, 3 parts starch ether, and 3 parts cellulose.

[0042] Example 2

[0043] The repair agent uses the following raw materials in parts by weight: 60 parts of sulfoaluminate cement, 10 parts of silica sol, 5 parts of modified bauxite, 5 parts of graphite powder, 2 parts of starch ether, and 3 parts of cellulose.

[0044] Example 3

[0045] The repair agent uses the following raw materials in parts by weight: 60 parts sulfoaluminate cement, 18 parts silica sol, 8 parts modified bauxite, 7 parts graphite powder, 4 parts starch ether, and 3 parts cellulose.

[0046] Example 4

[0047] Similar to Example 1, except that the repair agent used in Example 4 does not include modified bauxite.

[0048] Example 5

[0049] Similar to Example 1, except that the repair agent used in Example 5 does not include silica sol and graphite powder.

[0050] Example 6

[0051] Similar to Example 1, except that the repair agent used in Example 6 is sulfoaluminate cement.

[0052] Performance testing

[0053] The repair agents of Examples 1-6 were applied to the surface of standard concrete specimens and cured for 28 days according to the standard curing method. The impermeability was tested according to GB / T 50082-2009, the crack resistance was tested according to GB / T 29417-2012, and the flexural strength and compressive strength were determined according to GB / T 50081-2002. The test results are shown in Table 1.

[0054] Table 1. Performance of the repair agents in Examples 1-6

[0055]

[0056]

[0057] As shown in Table 1, compared with Examples 4-6, the repaired wall surfaces of Examples 1-3 have better crack resistance, impermeability, compressive strength, and flexural strength. Among them, compared with Examples 4-5, the repair agent of Example 6 is pure sulfoaluminate cement, and its crack resistance, impermeability, compressive strength, and flexural strength are actually slightly better. This may be because the components such as silica sol, graphite powder, and modified bauxite in the repair agent, in addition to sulfoaluminate cement, work synergistically and interact with each other. Adding individual components to sulfoaluminate cement would cause a decline in various properties.

[0058] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A building exterior wall repair process, characterized in that, Includes the following steps: S1. Locate the exterior wall where the crack is located and remove the dust and stains from the surface of the exterior wall; S2. Mark and delineate the area 30-40cm away from the crack as the core area, and extend the core area outward by 40-50cm to form the outer area, with the outer area enclosing the core area. Remove the surface layer of both the core area and the outer area until the concrete structure base is exposed. S3. Inject repair agent into the crack until the entire crack is filled with repair agent, and then continue to inject repair agent into the core area and the outer area until a repair agent layer with a thickness of 3-5mm is formed on the surface of the core area and the outer area. S4. Apply the first layer of cement mortar to the surface of the repair agent layer. Lay a layer of fiberglass cloth on the surface of the first layer of cement mortar in the outer area and a layer of wire mesh on the surface of the first layer of cement mortar in the core area. The wire mesh and fiberglass cloth partially overlap in the thickness direction. After the hardness of the first layer of cement mortar reaches half of the standard hardness, continue to apply the second layer of cement mortar on the surface of the first layer of cement mortar, fiberglass cloth, and wire mesh. The fiberglass cloth and wire mesh are located at the interface between the first layer of cement mortar and the second layer of cement mortar. S5. After the first and second layers of cement mortar have reached the standard hardness, apply the interface agent and wall paint to the surface of the cement mortar in sequence until the surface is flush with the original surface of the exterior wall. The repair agent uses raw materials comprising the following components in parts by weight: 50-60 parts of sulfoaluminate cement, 8-20 parts of silica sol, 5-8 parts of modified bauxite, 4-7 parts of graphite powder, 2-4 parts of starch ether, and 1-3 parts of cellulose; Two crack-stopping grooves perpendicular to the crack end face are chiseled at both ends of the crack along its length. The crack-stopping grooves have a V-shaped cross section and are located within the core area. The repair agent is injected into the crack-stopping grooves. The cement mortar contains glass fiber, the amount of glass fiber is 1% of the mass of cement mortar, and the diameter of the glass fiber is controlled at 4-5 mm and the length is controlled at 20-23 mm. The fiberglass cloth portion enters the core area, while the wire mesh portion enters the outer area. The areas where the fiberglass cloth and wire mesh overlap are connected with aramid fibers.

2. The building exterior wall repair process according to claim 1, characterized in that, The modified bauxite is prepared by the following steps: The bauxite was calcined at 600-700℃ for 3 hours. The calcined bauxite was then added to a 20-30% phosphite solution at a mass ratio of 1:5 and heated to 70-80℃ for 4 hours to obtain modified bauxite.

3. The building exterior wall repair process according to claim 1, characterized in that, In S4, the fiberglass cloth consists of two layers, with adjacent layers overlapping each other, and the overlapping portions are closely connected.

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