Compound sand blasting grinding material and application thereof in pretreatment of concrete coating

Abstract

The invention provides a compound sand blasting grinding material and application thereof in pretreatment of a concrete coating, and belongs to the technical field of new materials. The sand blasting grinding material compounded according to a specific formula provided by the invention shows excellent comprehensive performance in the sand blasting pretreatment of the concrete surface: various pollutants can be thoroughly removed, uniform and ideal surface roughness is efficiently formed so as to enhance the adhesion of a subsequent coating, dust generated in the sand blasting operation process is remarkably reduced, and meanwhile, high working efficiency is kept. The product is particularly suitable for concrete base surface pretreatment in the field of constructional engineering, the quality, the environmental protection property and the operation efficiency of sand blasting treatment can be effectively improved, an efficient, clean and reliable surface treatment solution is provided for protection, renovation and maintenance of a building structure, and the product is stable and reliable in comprehensive performance and is an optimal scheme meeting strict engineering requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new materials, and particularly relates to a compounded sandblasting abrasive and application thereof in concrete coating pretreatment. BACKGROUND

[0002] Sandblasting is a widely used surface pretreatment technology, and its core principle is to use high-speed sprayed abrasive particles to impact the surface of a workpiece to achieve the purpose of cleaning, roughening or strengthening through physical action. This technology has been quite mature in the fields of metal rust removal, coating removal, surface activation, etc. In recent years, with the growth of infrastructure construction and building maintenance needs, sandblasting technology plays an increasingly important role in the pretreatment of concrete surfaces. Concrete structures, such as bridges, tunnels, building exterior walls, industrial floors, hydraulic facilities, etc., often accumulate various pollutants such as oil stains, weathering layers, old coatings, floating slurry, efflorescence, etc. on the surface during their service life, or need to provide an ideal adhesion substrate for subsequent protective coatings (such as anticorrosive paint, waterproof layer, decorative layer) or repair mortar.

[0003] Compared with metal surfaces, sandblasting treatment on concrete surfaces faces more complex challenges and unique requirements: concrete is a porous, non-homogeneous and brittle material, and its strength, hardness and porosity are significantly affected by factors such as mix proportion, age, curing conditions, etc. Too strong or too high hardness of the abrasive may cause excessive damage to the surface, forming microcracks or loose aggregates; and improper selection of abrasive or poor control of parameters may result in incomplete cleaning or failure to form effective anchor patterns. The ideal sandblasting effect needs to completely remove surface pollutants (including penetrating stains), while forming a uniform, moderate and sufficient "key" effect roughness (anchor pattern depth) to maximize the adhesion of subsequent coatings or repair materials. The balance point between the two needs to be precisely grasped. The concrete sandblasting process is prone to generate a large amount of silica dust (especially when using abrasive containing quartz sand) and other fine particles. This not only seriously endangers the health of the operators (may cause silicosis), pollutes the surrounding environment, but also greatly reduces the work visibility and efficiency, and poses a major limitation to construction in indoor or densely populated areas. The treatment area of large concrete structures is often huge, and there is a high requirement for the efficiency of sandblasting operation. The consumption rate of abrasive, treatment speed, equipment wear, etc. are directly related to the engineering cost and progress. It is crucial to find an abrasive that can ensure treatment quality while taking into account high efficiency and economy.

[0004] Currently, there are various kinds of abrasives for concrete sandblasting on the market, including single abrasives and compounded abrasives, etc. Single abrasives often fail to meet all the above requirements simultaneously: some have high hardness but are easy to damage the substrate or generate a lot of dust, some have less dust but have low cutting efficiency or high cost, and some are environmentally friendly but have unsatisfactory roughness. Simple mixing often has problems such as poor performance synergy between components, unsatisfactory dust control, and low comprehensive cost-effectiveness. Therefore, in view of the special challenges of concrete surface treatment, it is urgent to develop a new type of compounded sandblasting abrasive that can achieve a breakthrough in effectively removing pollutants, accurately controlling surface roughness, significantly inhibiting dust generation, maintaining high operation efficiency, and meeting environmental and safety requirements, and provide a better solution for building protection, repair and renovation projects. SUMMARY

[0005] The purpose of the present application is to provide a compounded sandblasting abrasive and its application in concrete coating pretreatment, which provides an effective means for this field.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions: The present application provides a compounded sandblasting abrasive, which comprises the following components in parts by weight: blast furnace slag 30-50 parts, low-carbon bainite mixed abrasive 10-30 parts, copper ore sand 8-12 parts, garnet abrasive 8-12 parts, bauxite-based brown corundum 6-10 parts, chromite sand 3-8 parts, olivine sand 3-8 parts, and stainless steel slag 1-3 parts.

[0007] Preferably, the present application comprises the following components in parts by weight: blast furnace slag 34-45 parts, low-carbon bainite mixed abrasive 15-25 parts, copper ore sand 8-12 parts, garnet abrasive 8-12 parts, bauxite-based brown corundum 6-10 parts, chromite sand 4-6 parts, olivine sand 4-6 parts, and stainless steel slag 1-3 parts.

[0008] The present application also provides the application of the compounded sandblasting abrasive in the sandblasting treatment of concrete substrates.

[0009] Preferably, the concrete substrate comprises C25 strength grade concrete, C30 strength grade concrete, C40 strength grade concrete, steel fiber reinforced concrete, polypropylene fiber reinforced concrete, fly ash portland cement concrete, self-compacting concrete, or light aggregate concrete.

[0010] The present application also provides a sandblasting treatment method for concrete substrates, comprising the following steps: (a) removing loose foreign matter and oil stains on the surface of the substrate; (b) covering and protecting the non-treatment area; (c) the mixed compound sandblasting abrasive is loaded into a sandblasting device for sandblasting treatment.

[0011] Preferably, the working parameters of the sandblasting treatment are as follows: Working pressure: 0.4-0.8 MPa, nozzle distance: 100-400 mm, spray angle: 60-85°.

[0012] Preferably, in the sandblasting treatment, the spray gun moves at a uniform speed of 0.2-1.0 m / s, and the sweep overlap rate is 30-50%.

[0013] Preferably, in the sandblasting treatment, the environmental control meets the following requirements: the temperature of the concrete surface is higher than the dew point by ≥3℃, the relative humidity of the environment is <85%, and the environmental temperature is 5-45℃.

[0014] The application also provides a sandblasting system comprising the compound sandblasting abrasive and the sandblasting device.

[0015] Preferably, the sandblasting device comprises a dry sandblasting device, a wet sandblasting device, or a dust-free recycling sandblasting device.

[0016] Technical effects and advantages of the application: The specific formula compound sandblasting abrasive provided by the application exhibits excellent comprehensive performance in the concrete surface sandblasting pretreatment: it can completely remove various pollutants, efficiently form a uniform and ideal surface roughness to enhance the adhesion of the subsequent coating, significantly reduce the dust generation during the sandblasting operation, and maintain high working efficiency. The product is particularly suitable for the concrete base surface pretreatment in the field of construction engineering, can effectively improve the quality, environmental protection, and working efficiency of the sandblasting treatment, and provides an efficient, clean, and reliable surface treatment solution for the protection, renovation, and maintenance of building structures. The comprehensive performance of the product is stable and reliable, and it is an optimal solution that meets the stringent engineering requirements. DETAILED DESCRIPTION

[0017] The application provides a compound sandblasting abrasive comprising the following components in parts by weight: Furnace slag: 30-50 parts, low-carbon bainite mixed abrasive: 10-30 parts, copper ore sand: 8-12 parts, garnet abrasive: 8-12 parts, bauxite-based brown corundum: 6-10 parts, chromite sand: 3-8 parts, olivine sand: 3-8 parts, stainless steel slag: 1-3 parts.

[0018] In the application, the following components are included: Furnace slag: 30-50 parts. As the main component, it provides medium hardness, good breaking toughness, high cost-effectiveness, environmental protection (industrial by-product recycling), and helps to form a uniform anchor pattern.

[0019] Low carbon bainite mixed abrasive: 10~30 parts. Provide higher hardness and excellent wear resistance, with multi-angled structure, mainly responsible for cutting and breaking the concrete surface layer of floating slurry and weak layer, forming the key anchor.

[0020] Copper ore sand: 8~12 parts. Provide higher density and certain hardness, irregular particle shape, enhance the impact energy and cleaning efficiency of the abrasive, especially help to remove stubborn stains or old coating residues.

[0021] Garnet abrasive: 8~12 parts. High hardness, sharp edges, excellent cutting ability and cleaning speed, can effectively open the concrete capillary, improve the surface activity.

[0022] Alumina-based brown corundum: 6~10 parts. Provide very high hardness and sharp edges, as a "sharp soldier" component, deeply embedded and broken in the hardest surface layer area, significantly improving the roughening effect and anchor depth (Ra value).

[0023] Chromite sand: 3~8 parts. High density, medium hardness, most of the particles are near-spherical, mainly to increase the overall density of the abrasive, improve the impact kinetic energy transmission efficiency, and help to fill and homogenize the bottom of the anchor, reduce the risk of excessive fragmentation.

[0024] Olivine sand: 3~8 parts. Medium hardness, particle shape is diverse (flaky, granular), low dust, no free silicon hazard, good coverage and flushing effect, can gently remove loose materials on the surface and assist in cleaning, while adjusting the flowability of the abrasive flow.

[0025] Stainless steel slag: 1~3 parts. High hardness, high toughness, irregular particles, as a supplementary hard point, enhance the durability of the overall abrasive, reduce fragmentation consumption, and prolong the service life.

[0026] The application also provides the application of the compounded sandblasting abrasive in sandblasting treatment of a concrete base material. Preferably, the concrete base material includes C25 strength grade concrete, C30 strength grade concrete, C40 strength grade concrete, steel fiber reinforced concrete, polypropylene fiber reinforced concrete, fly ash portland cement concrete, self-compacting concrete, or light aggregate concrete.

[0027] The application also provides a sandblasting treatment method for a concrete base material, including the following steps: (a) removing loose foreign matter and oil stains on the surface of the base material; (b) covering and protecting the non-treatment area; (c) mixing and loading the above compounded sandblasting abrasive into a sandblasting device for sandblasting treatment.

[0028] Preferably, the sandblasting process operates at the following parameters: operating pressure of 0.4-0.8 MPa, nozzle distance of 100-400 mm, and spray angle of 60-85°. Preferably, during the sandblasting process, the spray gun moves at a constant speed of 0.2-1.0 m / s, with a sweep overlap ratio of 30-50%. Preferably, during the sandblasting process, the environmental control meets the following requirements: concrete surface temperature ≥3°C above the dew point, relative humidity <85%, and ambient temperature 5-45°C.

[0029] The present invention also provides a sandblasting system, comprising the above-mentioned composite sandblasting abrasive and sandblasting equipment; preferably, the sandblasting equipment comprises dry sandblasting equipment, wet sandblasting equipment or dust-free recovery sandblasting equipment.

[0030] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1 This embodiment provides a composite sandblasting abrasive formula (parts by weight): 40 parts of blast furnace slag, 20 parts of low-carbon bainite mixed abrasive, 10 parts of copper ore sand, 10 parts of garnet abrasive, 8 parts of bauxite-based brown corundum, 5 parts of chromite ore sand, 5 parts of olivine sand, and 2 parts of stainless steel slag.

[0032] This composite abrasive is designed for use in sandblasting equipment for pre-coating treatment of concrete substrates (such as floors, walls, bridge piers, pools, industrial facility foundations, etc.). The goal is to achieve the "concrete sandblasting cleaning" standards specified in the international standard ISO 8504-3 (i.e., complete removal of surface contaminants, weak layers, and laitance, and forming a uniform, clean, dry surface with sufficient roughness and activity).

[0033] The solution can be found in the following steps: Thoroughly inspect the concrete substrate, identifying and documenting defects such as cracks, holes, rusted steel bars, oil stains, chemical contamination, and crystallization (efflorescence). Severe defects require repair according to applicable regulations. Remove loose dust, debris, oil stains, and other large foreign matter from the surface. This can be done with an industrial vacuum cleaner, a broom, or low-pressure air. For oil stains, use a compatible cleaning agent and rinse thoroughly, ensuring the surface is dry.

[0034] Protect surrounding equipment, facilities and areas that do not require treatment (such as reserved steel bar heads, embedded parts, and adjacent coating areas) from the impact of abrasives and cover them tightly with special protective materials (such as thick plastic sheets, rubber sheets, and metal guards).

[0035] Mix the raw materials according to the above formula proportion, and ensure uniform mixing. Load the mixed abrasive into the sandblasting equipment hopper. Before operation, sample check the uniformity of abrasive mixing and whether there are lumps and impurities.

[0036] The working pressure: 0.5-0.7MPa is used as the core parameter of the treatment. If the pressure is too low, the cleaning efficiency is insufficient, and if it is too high, the concrete aggregate may be damaged.

[0037] The nozzle distance: 150-300mm is used. If the distance is too close, the impact force is too strong and the substrate is easily damaged, and if the distance is too far, the efficiency is reduced and the abrasive is dispersed.

[0038] The spray angle: 70-80 degrees (relative to the treated surface) is used. The near-vertical angle is beneficial to the impact and cutting action of the abrasive, forming an ideal anchor pattern. Avoid long-time vertical (90-degree) spraying to prevent the formation of too deep "craters".

[0039] Control the spray gun to move stably and uniformly, and avoid staying in the local area for too long. The specific speed needs to be determined on site according to the concrete strength, pollution degree, required anchor depth and equipment efficiency, and the general range is 0.3-0.8 m / s. Use overlapping scanning method (overlapping rate about 30-50%) to ensure uniform coverage without omission.

[0040] During the operation, the concrete surface temperature should be at least 3℃ higher than the dew point temperature, and the relative humidity of the environment should be less than 80% (ideally less than 60%). Avoid construction in rain, snow, strong wind or when there is visible water on the surface. The ambient temperature is recommended to be between 10℃ and 40℃.

[0041] Continue sandblasting until the concrete surface reaches the following state: All foreign contaminants (dust, oil stains, chemical residues, chalk marks, etc.), all loose or poorly adhered old coatings (if any), cement laitance layer and weak layer, exposed solid and uniform concrete body, aggregate is clearly visible but not excessively exposed or damaged (aggregate is not loose or broken), form a uniform, dense and matte clean surface. The surface should be uniformly light gray (depending on the color of the aggregate), without dark stains or uncleaned areas, achieving the specified surface roughness (anchor depth) of about 50-100 microns, the surface is clean and dry, without oil, grease, salt and other substances that affect the adhesion of the coating.

[0042] After sandblasting, use an industrial vacuum cleaner or broom to thoroughly remove all residual abrasive dust and debris from the surface and crevices of the substrate. Pay special attention to corners, edges, bolt holes, etc. where dust tends to accumulate, as residual dust can severely affect the adhesion of the coating. After removing large particles of residual dust, use clean, dry, oil-free, and water-free compressed air (pressure less than 0.2 MPa) to thoroughly blow the surface again to completely remove all fine dust. The blowing direction should be from high to low.

[0043] The sandblasted and cleaned concrete surface should be painted as soon as possible (usually within 4-8 hours, and no more than 24 hours), to prevent the surface from being contaminated again (dust, water vapor condensation). If there is a delay, the surface condition needs to be re-evaluated, and if necessary, a light secondary cleaning such as vacuuming or blowing should be performed.

[0044] Example 2 This example provides a compounded sandblasting abrasive formulation (by weight) 35 parts of blast furnace slag, 25 parts of low-carbon bainite mixed abrasive, 10 parts of copper ore sand, 10 parts of garnet abrasive, 8 parts of bauxite-based brown corundum, 5 parts of chromite sand, 5 parts of olivine sand, and 2 parts of stainless steel slag.

[0045] This compounded abrasive is designed specifically for use on sandblasting equipment for pre-treatment of concrete substrates (such as floors, walls, piers, pools, industrial facility foundations, etc.) before painting, with the goal of achieving the "concrete sandblasting cleaning" standard specified in international standard ISO 8504-3 (i.e. completely removing surface contaminants, weak layers, floating slurry, and forming a uniform, clean, dry, and sufficiently rough and active surface).

[0046] The treatment plan can be seen in the following steps: Thoroughly inspect the concrete substrate, identify and record defects such as cracks, holes, rust on steel bars, oil stains, chemical contamination, efflorescence, etc. Serious defects need to be repaired according to relevant specifications, and loose floating dust, debris, oil stains and other large foreign matter on the surface should be removed. Industrial vacuum cleaners, brooms or low-pressure air blowing can be used. For oil stains, compatible cleaning agents should be used for cleaning and thorough rinsing to ensure the surface is dry.

[0047] Protect surrounding equipment, facilities and areas that do not need to be treated (such as reserved steel bar heads, embedded parts, adjacent coating areas) from the impact of abrasive, and cover them tightly with special protective materials (such as thick plastic cloth, rubber board, metal board).

[0048] Mix the raw materials strictly according to the above formulation ratio to ensure uniform mixing. Fill the mixed compounded abrasive into the sandblasting equipment hopper. Before operation, sample check the uniformity of the abrasive mixture and whether there are lumps and impurities.

[0049] Working pressure: 0.5-0.7 MPa as the core parameters of the treatment, the lower pressure is not enough to clean, too high may damage the concrete aggregate.

[0050] The nozzle distance: 150-300 mm. Too close impact force is too strong to damage the substrate, too far away from the efficiency of the abrasive dispersion.

[0051] The spray angle: 70-80 degrees (relative to the surface being treated). Close to the vertical angle is conducive to the impact and cutting effect of abrasive, forming an ideal anchor. Avoid long vertical (90 degrees) spray, to prevent the formation of too deep "craters".

[0052] Control the gun to keep stable, uniform speed, avoid staying in the local area for too long. The specific speed needs to be determined according to the concrete strength, pollution level, the required anchor depth and equipment efficiency, usually in the range of 0.3-0.8 m / s. Use overlapping scanning method (overlapping rate of about 30-50%) to ensure uniform coverage without omission.

[0053] During the operation, the concrete surface temperature should be at least 3℃ higher than the dew point temperature, and the relative humidity of the environment should be less than 80% (ideally less than 60%). Avoid construction in rain, snow, strong wind or when there is visible water on the surface. The ambient temperature is recommended to be between 10℃ and 40℃.

[0054] Continue sandblasting until the concrete surface reaches the following state: All foreign contaminants (dust, oil, chemical residues, chalk marks, etc.), all loose or poorly adhered old coatings (if any), cement laitance and weak layers are completely removed, and the solid, uniform concrete body is exposed, with the aggregate clearly visible but not excessively exposed or damaged (no aggregate loosening or cracking), forming a uniform, dense, matte clean surface. The surface should be uniformly light gray (depending on the aggregate color), without dark stains or uncleaned areas, achieving the specified surface roughness (anchor depth) of about 50-100 microns, and the surface is clean and dry, free of oil, grease, salt and other substances that affect coating adhesion.

[0055] After sandblasting, use an industrial vacuum cleaner or broom to thoroughly clean all abrasive dust and debris remaining on the substrate surface and gaps. Since residual dust can severely affect coating adhesion, special attention should be paid to corners, edges, bolt holes and other areas prone to accumulation. After removing large particles, use clean, dry, oil-free and water-free compressed air (pressure less than 0.2 MPa) to blow the surface again, thoroughly removing all fine dust. Blow from high to low.

[0056] The concrete surface after sandblasting and cleaning should be coated as soon as possible (usually within 4-8 hours, and no more than 24 hours) to prevent the surface from being contaminated again (dust, water vapor condensation). If there is a delay, the surface condition needs to be re-evaluated, and if necessary, a light secondary cleaning such as dust removal or blowing should be performed.

[0057] Example 3 This example provides a compounded sandblasting abrasive formulation (by weight) Furnace slag 38 parts, low-carbon bainite mixed abrasive 22 parts, copper ore sand 12 parts, garnet abrasive 10 parts, bauxite-based brown corundum 6 parts, chromite sand 5 parts, olivine sand 5 parts, stainless steel slag 2 parts.

[0058] This compounded abrasive is designed for use on sandblasting equipment for pre-treatment of concrete substrates (such as floors, walls, piers, pools, industrial facility foundations, etc.) before coating. The goal is to achieve the "concrete sandblasting cleaning" standard specified in international standard ISO 8504-3 (i.e. completely removing surface contaminants, weak layers, efflorescence, and forming a uniform, clean, dry, and sufficiently rough and active surface).

[0059] The treatment plan can be seen in the following steps: Thoroughly inspect the concrete substrate, identify and record defects such as cracks, holes, rust on steel bars, oil stains, chemical contamination, efflorescence, etc. Serious defects need to be repaired according to relevant specifications, and loose dust, debris, oil stains and other large foreign matter on the surface should be removed. Industrial vacuum cleaner, broom or low-pressure air blowing can be used. For oil stains, compatible cleaning agents should be used for cleaning and thorough rinsing to ensure the surface is dry.

[0060] Protect the surrounding equipment, facilities and areas that do not need to be treated (such as reserved steel bars, embedded parts, adjacent coating areas) from the impact of abrasive, and cover them tightly with special protective materials (such as thick plastic cloth, rubber plate, metal shield).

[0061] Mix the raw materials strictly according to the above formulation ratio to ensure uniform mixing. Put the mixed compounded abrasive into the sandblasting equipment hopper. Before operation, sample check the uniformity of the abrasive mixture and whether there are lumps and impurities.

[0062] Use working pressure: 0.6-0.75 MPa as the core parameter for treatment. If the pressure is too low, the cleaning efficiency will be insufficient, and if the pressure is too high, the concrete aggregate may be damaged.

[0063] Use nozzle distance: 150-300 mm. If the distance is too close, the impact force will be too strong and the substrate may be damaged, and if the distance is too far, the efficiency will be reduced and the abrasive will be dispersed.

[0064] Use an angle of 70-80 degrees (relative to the surface being treated). Near perpendicular angles are beneficial for the impact and cutting action of the abrasive, resulting in ideal anchorage. Avoid long periods of perpendicular (90 degree) blasting to prevent the formation of excessively deep "craters".

[0065] Control the movement of the blasting gun to be steady and uniform, avoiding long periods of time spent in one area. The exact speed will depend on the strength of the concrete, the level of contamination, the desired depth of anchorage and the efficiency of the equipment. Typical speeds range from 0.3 to 0.8 m / s. Use an overlapping sweep pattern (overlapping rate of approximately 30-50%) to ensure complete coverage.

[0066] During the operation, the temperature of the concrete surface should be at least 3°C above the dew point, and the relative humidity of the environment should be less than 80% (ideally less than 60%). Avoid working in rain, snow, strong winds or when there is visible standing water on the surface. The ambient temperature is recommended to be between 10°C and 40°C.

[0067] Continue sandblasting until the concrete surface reaches the following state: All foreign contaminants (dirt, oil, chemical residues, chalk marks, etc.), all loose or poorly adhered old coatings (if any), cement laitance and weak layers are completely removed, leaving a solid, uniform concrete substrate with clearly visible aggregates but no excessive exposure or damage (no aggregate loosening or chipping), and a clean, matte, dense surface. The surface should have a uniform light gray tone (depending on the color of the aggregate), with no dark stains or uncleaned areas, and a specified surface roughness (anchorage depth) of approximately 50-100 microns, and a clean, dry surface free of oil, grease, salt and other substances that could affect coating adhesion.

[0068] After sandblasting, use an industrial vacuum cleaner or broom to thoroughly remove all abrasive dust and debris from the surface of the substrate and from crevices. Pay special attention to corners, edges, bolt holes and other areas where dust tends to accumulate, as residual dust can severely affect coating adhesion. After removing large particles, use clean, dry, oil-free and water-free compressed air (pressure less than 0.2 MPa) to blow the surface again, thoroughly removing all fine dust. Blow from top to bottom.

[0069] The concrete surface, after sandblasting and cleaning, should be painted as soon as possible (usually within 4-8 hours, and no more than 24 hours), to prevent the surface from being contaminated again (dust, water condensation). If there is a delay, the surface condition should be re-evaluated and, if necessary, lightly cleaned again, such as vacuuming or blowing.

[0070] Example 4 This example provides a compounded sandblasting abrasive formulation (in parts by weight) Blast furnace slag 45 parts, low-carbon bainite mixed abrasive 20 parts, copper ore sand 10 parts, garnet abrasive 10 parts, bauxite-based brown corundum 6 parts, chromite sand 4 parts, olivine sand 4 parts, stainless steel slag 2 parts.

[0071] This compound abrasive is designed for use on sandblasting equipment, used for pre-treatment of concrete substrates (such as floors, walls, piers, pools, industrial facilities foundation, etc.) before painting, aiming to achieve the "concrete sandblasting cleaning" standard specified in international standard ISO 8504-3 (i.e. completely remove surface contaminants, weak layers, efflorescence, and form a uniform, clean, dry, and active surface with sufficient roughness).

[0072] The treatment plan can refer to the following steps: Thoroughly inspect the concrete substrate, identify and record defects such as cracks, holes, rust on steel bars, oil stains, chemical contamination, efflorescence, etc. Serious defects need to be repaired according to relevant specifications, and loose dust, debris, oil stains and other large foreign matter on the surface should be removed. Industrial vacuum cleaner, broom or low-pressure air blowing can be used. For oil stains, compatible cleaning agent should be used for cleaning and thorough rinsing to ensure the surface is dry.

[0073] Protect the surrounding equipment, facilities and areas that do not need to be treated (such as reserved steel bar heads, embedded parts, adjacent coating areas) from the impact of abrasive, and use special protective materials (such as thick plastic cloth, rubber plate, metal shield) to cover them tightly.

[0074] Mix the raw materials strictly according to the above formula ratio to ensure uniform mixing. Put the mixed compound abrasive into the sandblasting equipment hopper. Before operation, sample check the uniformity of the abrasive mixture and whether there are lumps and impurities.

[0075] Use working pressure: 0.5-0.7MPa as the core parameter of treatment, too low pressure will not clean effectively, too high pressure may damage the concrete aggregate.

[0076] Use nozzle distance: 100-200mm. Too close distance will cause too strong impact and damage the substrate, too far distance will reduce the efficiency and dispersion of the abrasive.

[0077] Use jet angle: 70-80 degrees (relative to the treated surface). Near vertical angle is beneficial to the impact and cutting action of the abrasive, forming ideal anchor marks. Avoid long time vertical (90 degree) jetting to prevent forming too deep "craters".

[0078] Control the spray gun to move stably and uniformly, avoid staying in local area for too long. The specific speed needs to be determined on site according to the concrete strength, degree of contamination, required anchor depth and equipment efficiency, usually in the range of 0.3-0.8 m / s. Use overlapping sweeping method (overlapping rate about 30-50%) to ensure uniform coverage without omission.

[0079] During the work, the concrete surface temperature should be at least 3°C higher than the dew point temperature, and the relative humidity of the environment should be less than 80% (ideally less than 60%). Avoid construction in rainy, snowy, windy weather or when there is visible water on the surface. The ambient temperature is recommended to be between 10°C and 40°C.

[0080] Continue sandblasting until the concrete surface reaches the following state: Completely remove all foreign contaminants (dust, oil, chemical residues, chalk marks, etc.), all loose or poorly adhered old coatings (if any), cement laitance layer and weak layer, expose the solid and uniform concrete body, the aggregate is clearly visible but not excessively exposed or damaged (no aggregate loosening or fragmentation), form a uniform, dense, matte clean finish. The surface should have a uniform light gray tone (depending on the color of the aggregate), no dark stains or uncleaned areas, achieve the specified surface roughness (anchor depth) of about 50-100 microns, the surface is clean and dry, free of oil, grease, salt and other substances that affect coating adhesion.

[0081] After sandblasting, use an industrial vacuum cleaner or broom to thoroughly remove all abrasive dust and debris remaining on the substrate surface and in the gaps. Pay special attention to corners, edges, bolt holes and other areas where dust tends to accumulate, as residual dust can severely affect coating adhesion. After removing large particles, use clean, dry, oil-free and water-free compressed air (pressure less than 0.2 MPa) to blow the surface again, thoroughly removing all fine dust. Blow from high to low.

[0082] The sandblasted and cleaned concrete surface should be painted as soon as possible (usually within 4-8 hours, no more than 24 hours), to prevent the surface from being contaminated again (dust, water condensation). If there is a delay, the surface condition needs to be re-evaluated and, if necessary, lightly cleaned again, such as vacuuming or blowing.

[0083] Example 5 This example provides a compounded sandblasting abrasive formulation (by weight) 30 parts of blast furnace slag, 25 parts of low-carbon bainite mixed abrasive, 15 parts of copper ore sand, 10 parts of garnet abrasive, 8 parts of bauxite-based brown corundum, 5 parts of chromite sand, 5 parts of olivine sand, and 2 parts of stainless steel slag.

[0084] This compounded abrasive is designed for use on sandblasting equipment for pre-treatment of concrete substrates (such as floors, walls, piers, pools, industrial facility foundations, etc.) before painting, with the goal of achieving the "concrete sandblasting cleaning" standard specified in international standard ISO 8504-3 (i.e. completely removing surface contaminants, weak layers, laitance, and forming a uniform, clean, dry, rough and active surface).

[0085] The processing scheme can refer to the following steps: Thoroughly inspect the concrete substrate, identify and record defects such as cracks, holes, rusted reinforcement, oil stains, chemical contamination, efflorescence, etc. Serious defects need to be repaired according to relevant specifications, and loose dust, debris, oil stains and other large foreign matter on the surface should be removed. Industrial vacuum cleaner, broom or low-pressure air blowing can be used. For oil stains, compatible cleaning agent should be used for cleaning and thorough rinsing to ensure the surface is dry.

[0086] Protect the surrounding equipment, facilities and areas that do not need to be processed (such as reserved reinforcement heads, embedded parts, adjacent coating areas) from the impact of abrasive, and cover them tightly with special protective materials (such as thick plastic cloth, rubber plate, metal plate).

[0087] Mix the raw materials strictly according to the above formula proportion, and ensure uniform mixing. Put the mixed abrasive into the sandblasting equipment hopper. Before operation, sample check the uniformity of abrasive mixing and whether there are lumps and impurities.

[0088] Use working pressure: 0.5-0.7MPa as the core parameter of processing. If the pressure is too low, the cleaning efficiency will be insufficient, and if the pressure is too high, the concrete aggregate may be damaged.

[0089] Use nozzle distance: 150-300mm. If the distance is too close, the impact force will be too strong and the substrate may be damaged, and if the distance is too far, the efficiency will be reduced and the abrasive will be dispersed.

[0090] Use spray angle: 70-80 degrees (relative to the surface being treated). Near vertical angle is beneficial to the impact and cutting action of abrasive, forming ideal anchor pattern. Avoid long time vertical (90 degrees) spraying to prevent forming too deep "craters".

[0091] Control the spray gun to move stably and uniformly, and avoid staying in local area for too long. The specific speed should be determined on site according to the concrete strength, pollution degree, required anchor depth and equipment efficiency, usually in the range of 0.3-0.8 m / s. Use overlapping scanning method (overlapping rate about 30-50%) to ensure uniform coverage without omission.

[0092] During operation, the temperature of the concrete surface should be at least 5℃ higher than the dew point temperature, and the relative humidity of the environment should be less than 75% (ideally less than 60%). Avoid construction in rain, snow, strong wind or when there is visible water on the surface. The ambient temperature is recommended to be between 10℃ and 40℃.

[0093] Continue sandblasting until the concrete surface reaches the following state: All foreign contaminants (dirt, oil, chemical residues, chalk marks, etc.), all loose or poorly adhered old coatings (if any), cement laitance and weak layers are completely removed, leaving a clean, even, matte finish of the solid, uniform concrete mass, with aggregate clearly visible but not excessively exposed or damaged (no aggregate loose, chipped), forming a uniform, dense, matte clean finish. The surface should exhibit a uniform light gray tone (depending on the color of the aggregate), free of dark stains or uncleaned areas, achieving the specified surface roughness (anchor pattern depth) generally in the order of 50 - 100 microns, the surface is clean and dry, free of oil, grease, salt and other substances that can affect the adhesion of the coating.

[0094] After sandblasting, all abrasive dust and debris remaining on the surface of the substrate and in the joints is completely removed using an industrial vacuum cleaner or broom. Since the remaining dust can seriously affect the adhesion of the coating, special attention should be paid to the corners, edges, bolt holes and other places where it tends to accumulate. After removing the large particles remaining, the surface is again thoroughly blown with clean, dry, oil-free and water-free compressed air (pressure less than 0.2 MPa) to completely remove all fine dust. The blowing direction is from top to bottom.

[0095] The concrete surface treated and cleaned should be painted as soon as possible (usually within 4-8 hours, and at most within 24 hours) to prevent the surface from being contaminated again (dust, water vapor condensation). If there is a delay, the surface condition needs to be re-evaluated and, if necessary, a light secondary cleaning such as vacuuming or blowing is performed.

[0096] Experimental Example The performance differences of the standard formula (experimental group A) and four control groups (B, C, D, E) in the treatment of concrete surfaces are verified, focusing on the evaluation of surface cleanliness, roughness, treatment efficiency and dust generation.

[0097] Based on the scheme of Example 1, the following group settings are made: Experimental group A: standard formula (blast furnace slag 40, low-carbon bainite 20, copper ore sand 10, garnet 10, brown corundum 8, chromite sand 5, olivine sand 5, stainless steel slag 2) Control group B: remove the removed chromite sand + stainless steel slag Control group C: remove the chromite sand + stainless steel slag + garnet Control group D: increase the blast furnace slag to 60 parts and reduce the brown corundum to 3 parts Control group E: increase the copper ore sand to 20 parts and reduce the garnet to 5 parts The experimental steps are as follows: The abrasive is prepared, and the experimental personnel weigh the raw materials according to the formula of each group, mix them in a V-type mixer at a speed of 20 rpm for 30 minutes to ensure uniformity. After mixing, the abrasive is sealed and stored in a dry environment.

[0098] Concrete preparation: C30 standard concrete specimens (300 mm × 300 mm × 50 mm) were prepared by the experimenter and cured for 28 days.

[0099] Pre-coating of the concrete surface with simulated contaminants: engine oil (5 g / m 2 ), cement laitance (0.5 mm thick), dust (ISO 12103-A2 fine sand evenly spread).

[0100] Sandblasting: the same pressure-feed sandblaster was used, with a fixed working pressure of 0.65 MPa.

[0101] The nozzle was positioned 250 mm from the specimen, at an angle of 75°, with a movement speed of 0.5 m / s and an overlap rate of 40%.

[0102] Five specimens were treated in each group, with the treatment time strictly controlled at 120 seconds per specimen.

[0103] Performance testing (1) Surface cleanliness The tester visually inspected the residual rate of surface contaminants according to ISO 8504-3 (0% being the best).

[0104] The colorimeter was used to measure the surface lightness value (L), with a reference value of L = 65.0 ± 1.5 for uncontaminated concrete.

[0105] (2) Surface roughness The tester used a stylus-type roughness meter (Mitutoyo SJ-410) to measure the profile arithmetic mean deviation (Ra, unit: μm) at 5 points on the diagonal of each specimen.

[0106] (3) Treatment efficiency The tester weighed the abrasive before and after sandblasting, and calculated the material removal rate per unit time (g / min).

[0107] The time required to achieve the ISO cleanliness standard (seconds) was recorded.

[0108] (4) Dust generation A dust collection filter membrane (diameter 47 mm) was placed in the sandblasting chamber, and the dust concentration (mg / m 3 ) was calculated using the weighing method.

[0109] Four, experimental results Table 1 Comparison of surface treatment performance (n = 5, x̄ ± SD)

[0110] The results show that the standard formulation (Group A) performs best in the concrete shot blasting pretreatment. It confirms that the solution provided by the invention can effectively remove contaminants, form a suitable surface roughness, reduce dust generation, while maintaining a high work efficiency. This effect is due to the combination of components: hard materials (brown corundum, chromite sand) provide strength, ductile materials (stainless steel slag) reduce clogging, cutting materials (garnet, copper ore sand) are responsible for stripping the pollution layer, and filler materials (blast furnace slag) control costs. The differences in the comparative groups further illustrate the importance of the formulation balance: Group B lacks chromite sand and stainless steel slag, and the cleaning effect is poor, and the surface roughness is insufficient; Group C further reduces garnet, and the cutting ability is significantly reduced, and the base surface cannot be thoroughly treated; Group D increases too much blast furnace slag, and the dust volume increases significantly, although it can increase the roughness, but the pollution is serious; Group E increases the proportion of copper ore sand, which causes the particles to be embedded in the concrete, resulting in new pollution and slowing down the progress. Overall, the standard formulation achieves a balance of cleaning effect, surface quality, environmental protection, and efficiency through reasonable material combination, and is a more reliable choice; arbitrarily reducing components or changing the proportion will affect the final effect.

[0111] The above only describes the preferred embodiments of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the principles of the present application, several improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A compound sandblasting abrasive, characterized in that: The composition comprises the following components in parts by weight: 30-50 parts of blast furnace slag, 10-30 parts of low-carbon bainite mixed abrasive, 8-12 parts of copper ore sand, 8-12 parts of garnet abrasive, 6-10 parts of bauxite-based brown corundum, 3-8 parts of chromite ore sand, 3-8 parts of olivine sand, and 1-3 parts of stainless steel slag.

2. The compound sandblasting abrasive according to claim 1, characterized in that: It is composed of the following components in parts by weight: 34-45 parts of blast furnace slag, 15-25 parts of low-carbon bainite mixed abrasive, 8-12 parts of copper ore sand, 8-12 parts of garnet abrasive, 6-10 parts of bauxite-based brown corundum, 4-6 parts of chromite ore sand, 4-6 parts of olivine sand, and 1-3 parts of stainless steel slag.

3. Use of the compound sandblasting abrasive according to claim 1 or 2 in sandblasting treatment of concrete substrates.

4. The use according to claim 3, characterized in that The concrete base material includes C25 strength grade concrete, C30 strength grade concrete, C40 strength grade concrete, steel fiber reinforced concrete, polypropylene fiber reinforced concrete, fly ash silicate cement concrete, self-compacting concrete or lightweight aggregate concrete.

5. A method for sandblasting a concrete substrate, characterized in that: The following steps are involved: (a) Remove loose foreign matter and oil stains from the substrate surface; (b) Covering to protect non-treated areas; (c) The composite sandblasting abrasive according to claim 1 or 2 is mixed and loaded into a sandblasting device for sandblasting.

6. The method for sandblasting a concrete substrate according to claim 5, wherein: The working parameters of the sandblasting process are: Working pressure 0.4~0.8 MPa, nozzle distance 100~400 mm, spray angle 60~85°.

7. The sandblasting method for concrete substrate according to claim 5, characterized in that: During the sandblasting process, the spray gun moves at a constant speed of 0.2-1.0 m / s, and the sweep overlap rate is 30-50%.

8. The sandblasting method for concrete substrate according to claim 5, characterized in that: During the sandblasting process, the environmental control meets the following requirements: the concrete surface temperature is higher than the dew point by ≥3°C, the relative humidity is <85%, and the ambient temperature is 5-45°C.

9. A sandblasting system, characterized in that: The invention comprises the composite sandblasting abrasive and sandblasting equipment according to claim 1 or 2.

10. The sandblasting system according to claim 9, wherein: The sandblasting equipment includes dry sandblasting equipment, wet sandblasting equipment or dust-free recovery sandblasting equipment.

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