Preparation method and preparation system of high-strength foam glass aggregate for concrete manufacturing and lightweight concrete prepared from high-strength foam glass aggregate

Abstract

The invention relates to a preparation technology of civil engineering materials, in particular to a preparation method of high-strength lightweight aggregate for concrete products, which comprises the following steps: crushing soda-lime glass into fine glass powder; screening the glass powder to obtain glass powder particles of which the sizes are within a preset size range; fully mixing the screened glass powder particles and limestone powder to obtain a uniformly distributed powder mixture; transferring the powder mixture into a disc granulator; starting the disc granulator, and regularly spraying a sodium silicate solution onto the powder mixture to generate granules; dehydrating the produced particles in an oven; placing the dried particles on a setter plate in a muffle furnace, wherein all the particles are spaced apart; the particles are subjected to a specific temperature procedure for a foaming process. The invention also relates to a high-strength lightweight aggregate for concrete products and a system for preparing the same.

Description

Technical Field

[0001] The invention relates to a preparation technology of civil engineering materials, in particular to the preparation of foam glass aggregate for concrete. Background Art

[0002] In the current market, foam glass is a man-made porous material made from glass powder and a foaming agent at high temperatures. Using foam glass in concrete promises to reduce weight and improve thermal insulation. However, traditional foam glass products are designed for thermal insulation and have low mechanical strength. Furthermore, they are typically produced in blocks or sheets, requiring multiple additives for foaming and demolding. Therefore, they cannot be used directly as aggregate in concrete.

[0003] Prior art, patent application CN118005350A discloses a lightweight, thermally insulating foam concrete and its preparation method. The concrete uses expanded vitrified microspheres (75 to 95 μm) as the primary lightweight aggregate, with foam glass particles, perlite, expanded vermiculite, and hollow vitrified microspheres (30 to 100 μm in diameter) as fillers, with the fillers accounting for 10% to 15% of the total lightweight aggregate mixture. Additional lightweight aggregates are selected from one or more of aerogel particles, polystyrene particles, diatomaceous earth particles, and ceramic particles. However, this patent application does not disclose a method for producing the foam glass.

[0004] Furthermore, Chinese invention patent application publication number CN107382077A discloses a method for preparing open-cell foam glass, comprising washing, drying, and crushing waste glass, followed by sieving to obtain glass powder, mixing the powder with rice husk powder, calcium carbonate, chitosan solution, glutaraldehyde, polyethylene glycol 2000, a surfactant, and a sintering aid to obtain a wet material, cold-pressing the material, freezing it with recycled liquid nitrogen, allowing it to thaw naturally, followed by vacuum freeze-drying, heat-insulating sintering, demolding, high-pressure steam curing, and finally washing and drying to obtain the open-cell foam glass. However, the foam glass obtained by this preparation method is not granular and cannot be directly used as a concrete aggregate. Furthermore, the material has low strength and cannot meet the strength requirements for concrete aggregate.

[0005] In view of this, it is necessary to propose a method for preparing high-strength foam glass for concrete to solve at least part of the above problems. Summary of the Invention

[0006] Therefore, the object of the present invention is to solve these problems. The present invention provides a method for preparing high-strength foam glass aggregates of different sizes without additives.

[0007] According to one aspect of the present invention, there is provided a method for preparing a high-strength lightweight aggregate for concrete products, the method comprising: crushing soda-lime glass into fine glass powder; sieving the glass powder to obtain glass powder particles having a size within a predetermined size range; thoroughly mixing the sieved glass powder particles and limestone powder to obtain a uniformly distributed powder mixture; transferring the powder mixture to a disc granulator; turning on the disc granulator and periodically spraying a sodium silicate solution onto the powder mixture to produce particles; dehydrating the produced particles in an oven; placing the dried particles on a setter in a muffle furnace, wherein all the particles are spaced apart; and subjecting the particles to a temperature program for performing a foaming process.

[0008] The foam glass produced by the present invention can be sieved into different gradations and has the mechanical strength required for use as a lightweight aggregate, which helps reduce the weight of concrete and improve its thermal insulation performance.

[0009] In the present preparation method, glass powder and a foaming agent are simply mixed in a disc granulator and rolled into granules of varying sizes. A sodium silicate solution is sprayed on as a binder to impart initial strength to the granules. During the foaming process, the granules are placed directly on a setter plate within the furnace.

[0010] This invention improves upon existing methods for producing foamed glass. The raw materials used are glass powder and a foaming agent, without any other additives. Using a disc granulator, the mixture of glass powder and foaming agent is converted into granules of varying sizes. These granules are then foamed directly in a muffle furnace.

[0011] As a preferred aspect of the present invention, the mass ratio of the glass powder to the limestone powder is 100:3.

[0012] As a preferred aspect of the present invention, the chemical formula of the sodium silicate solution is Na2O•3.4SiO2•H2O.

[0013] As a preferred aspect of the present invention, the produced particles are dried at a temperature of 90° C. for 2 hours.

[0014] As a preferred aspect of the present invention, the disc inclination angle of the disc granulator is set to 45° with respect to the normal line, and the rotation speed is 30 rpm.

[0015] As a preferred aspect of the present invention, the temperature program is set by: heating the muffle furnace from room temperature to 250°C at a rate of 5°C / min; maintaining the temperature of the muffle furnace at 250°C for 20 minutes to preheat and uniformly heat the particles; heating the muffle furnace from 250°C to 850°C at a rate of 5°C / min to reach the foaming temperature; maintaining the temperature of the muffle furnace at 850°C for 30 minutes to promote the foaming process; cooling the muffle furnace from 850°C to 600°C at a rate of 10°C / min; maintaining the temperature of the muffle furnace at 600°C for 20 minutes to stabilize the pores generated in the foam particles; and naturally cooling the muffle furnace from 600°C to room temperature to eliminate residual stress in the foam particles.

[0016] As a preferred aspect of the present invention, the size of the glass powder is 30 to 80 meshes, and the size of the limestone powder is about 8000 meshes.

[0017] As a preferred aspect of the present invention, the chemical formula of the sodium silicate solution is Na2O•3.4SiO2•H2O.

[0018] According to another aspect of the present invention, there is also provided a high-strength lightweight aggregate prepared by the above method. The size of the aggregate is 10mm-20mm, and the bulk density is about 580kg / m 3 , particle density is about 1100kg / m 3 , the particle compressive strength is about 9.93MPa.

[0019] According to another aspect of the present invention, there is also provided a concrete, the raw material components of which include: cement, the amount of which is 420kg / m 3 ; Foam glass aggregate, dosage is 427kg / m 3 ; Fine river sand aggregate, dosage is 753.1kg / m 3 ;Tap water, dosage is 189kg / m 3 , wherein the foam glass aggregate is the above-mentioned high-strength lightweight aggregate.

[0020] According to another aspect of the present invention, a preparation system for manufacturing the aforementioned high-strength lightweight aggregate is also provided, which includes: a grinding device for crushing soda-lime glass into fine glass powder; a screening device for screening the fine glass powder to obtain glass powder within a predetermined size range; a mixing device for fully mixing the glass powder with a foaming agent to obtain a powder mixture; a disc granulator for feeding the powder mixture into a disc of the disc granulator and moving the powder mixture within the disc; a spraying device for regularly spraying a binder onto the powder mixture in the disc, wherein the powder mixture produces particles under the action of the binder; an oven for dehydrating the particles; and a muffle furnace capable of raising and lowering the temperature according to a predetermined program so that the particles foam in the muffle furnace and form foamed glass aggregate.

[0021] Some of the other features and advantages of the present invention will be apparent to those skilled in the art after reading this application, and the other parts will be described in the following detailed description in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the foaming temperature program diagram of the present invention;

[0023] Figure 2 It is the mechanical structure of the disc granulator. DETAILED DESCRIPTION

[0024] In the following description, the details of the present invention are set forth as preferred embodiments. Those skilled in the art will appreciate that modifications, including additions and / or substitutions, may be made without departing from the scope and spirit of the present invention. Specific details may be omitted so as not to obscure the present invention; however, this disclosure is written to enable those skilled in the art to practice the teachings herein without undue experimentation.

[0025] Certain directional terms used in the following description of the drawings, such as "inner," "outer," "above," "below," and other directional terms, should be understood to have their normal meanings and refer to those directions when the drawings are normally viewed. Unless otherwise indicated, the directional terms used in this specification are generally in accordance with conventional directions understood by those skilled in the art.

[0026] The terms "first", "first", "second", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are used to distinguish one component from other components.

[0027] The terms "joining", "connection" and similar terms used in the present invention include both indirect connection of two components with the aid of an intermediate layer (such as an adhesive, a weld, etc.) or an intermediate piece (such as a connector, a transition piece, etc.), and direct connection of two components without the aid of any intermediate layer (such as an adhesive, a weld, etc.) or intermediate piece (such as a connector, a transition piece, etc.).

[0028] Aggregate, also known as aggregate, is a granular material that acts as a framework and filler in composite materials such as concrete and mortar. Generally speaking, lightweight aggregate refers to aggregate with a bulk density of less than 1000 kg / m³. This effectively reduces the weight of a building and is crucial for long-span structures, high-rise buildings, and special buildings with strict weight requirements. Furthermore, due to its numerous internal pores, which are filled with air, which has a very low thermal conductivity, lightweight aggregate possesses excellent thermal insulation properties, effectively reducing a building's energy consumption and improving its energy efficiency.

[0029] Foam glass is a man-made porous material made from glass powder and a foaming agent at high temperatures. Due to its lightweight and porous properties, foam glass has the potential to be used as a lightweight aggregate to reduce the weight of concrete and improve its thermal insulation properties. However, traditional foam glass is designed for thermal insulation and is typically produced in blocks or slabs. Known methods for producing foam glass include mold filling and die-pressing and sintering. The mold filling method is the most basic method for producing foam glass. It involves combining waste glass, a foaming agent, and other raw materials in a specific proportion, placing them into a mold, compacting them, and then placing them in a foaming furnace for foaming. A release agent is typically applied to the inner surface of the mold to prevent the raw materials from sticking to the mold. The die-pressing and sintering method involves combining the raw materials, adding a lubricant, granulating them, drying them, placing them into a mold, and then feeding them into a foaming furnace for foaming. These production methods often use additives such as surfactants, sintering aids, and release agents during production. When using the crushing method to produce aggregate from bulk and slab foam glass, this process can introduce micro-defects into the resulting aggregate. Although some commercial foam glass particles are available, they cannot be used directly as aggregate in concrete due to their relatively low mechanical strength. To address these problems, a preparation method was invented to produce foam glass aggregates of different sizes with improved mechanical strength.

[0030] Important aspects of the method of the present invention are the selection of raw materials, the granulation process of the aggregate, and the foaming process. As for the raw materials, the glass powder is obtained by crushing recycled glass into particles of 30 to 80 mesh. To ensure the wide applicability of the present invention, the glass used is soda-lime glass, which is the most commonly used type in the world. The foaming agent used is limestone powder with a particle size of 8000 mesh. Limestone was chosen because it is easily available and low in cost. During the foaming process, the limestone powder decomposes, releasing carbon dioxide gas, which creates pores in the molten glass.

[0031] During the aggregate granulation stage, a disc granulator is used to obtain aggregates of varying sizes. Sodium silicate solution (chemical formula: Na2O•3.4SiO2•H2O, modulus 3.4) is sprayed as a binder to bind the glass powder and limestone powder together. For the foaming process, the temperature program of the muffle furnace is as follows: Figure 1 The program is designed to take into account the decomposition of limestone powder and the melting of glass powder. The temperature program is divided into seven stages:

[0032] (i) A muffle furnace was heated from room temperature (approximately 20°C) to 250°C at a rate of 5°C / min.

[0033] (ii) The furnace temperature was maintained at 250 °C for 20 min to preheat and uniformly heat the particles.

[0034] (iii) The muffle furnace was heated from 250°C to 850°C at a rate of 5°C / min to reach the foaming temperature.

[0035] (iv) The furnace temperature was maintained at 850 °C for 30 min to facilitate the foaming process.

[0036] (v) The muffle furnace was cooled from 850°C to 600°C at a rate of 10°C / min.

[0037] (vi) The furnace temperature was maintained at 600 °C for 20 min to stabilize the generated pores.

[0038] (vii) The muffle furnace is naturally cooled from 600 °C to room temperature (about 20 °C) to eliminate any residual stress.

[0039] The steps of preparing foam glass aggregate using the method of the present invention are summarized as follows:

[0040] 1. Recover and clean soda lime glass products. Grind the soda lime glass into fine powder and sieve to obtain particles in the range of 30-80 mesh.

[0041] 2. Mix the glass powder and limestone powder thoroughly to ensure even distribution. The mass ratio of glass powder to limestone powder should be 100:3.

[0042] 3. Transfer the mixed powder to a disc granulator. Set the disc plane at a 45° angle to the normal and the disc speed to 30 rpm.

[0043] 4. Turn on the disc granulator and periodically spray the sodium silicate solution onto the powder mixture.

[0044] 5. After a few minutes, granules will begin to form. It is recommended to pause the disc granulator and collect the granules periodically. This allows the remaining powder to be sprayed with the binder, thus forming additional granules.

[0045] 6. Dry the produced particles in an oven at 90°C for 2 hours. This process dehydrates the binder, improves the initial strength of the foam glass aggregate, and makes it more suitable for storage.

[0046] 7. Place the dried pellets on a setter plate in the muffle furnace. Make sure all pellets are spaced apart to prevent them from sticking together during the foaming process.

[0047] 8. Follow Figure 1 The foaming temperature program was carried out as shown.

[0048] 9. Once the furnace temperature has cooled naturally to room temperature, remove the foam glass aggregate from the furnace and sieve it to the required size.

[0049] Figure 2 An example of the mechanical configuration of a disc granulator according to one embodiment of the present invention is shown. The disc has a diameter of 50 cm. During the aggregate granulation stage, a scraper is positioned at the edge of the disc, and a binder (sodium silicate solution) is sprayed onto the powder around the scraper.

[0050] Specifically, when a disc granulator is in operation, an electric motor drives the disc at a constant speed through a speed reducer. The rotating disc exerts centrifugal force on the material, causing it to move toward the disc's edge. Friction also causes the powder mixture to rise with the disc to a certain height. Furthermore, once the material reaches a certain height, gravity causes it to roll downward, causing the powder mixture to follow a specific trajectory on the disc, resulting in small particle nuclei.

[0051] As the small particle nuclei roll on the disc, they continuously adhere to the surrounding powder, gradually growing larger. Newly formed small particles also collide and squeeze with each other, sticking together to form larger particles. When the particles reach a certain size, gravity and centrifugal force cause them to overflow or roll off the edge of the disc. After removal, the particles enter the subsequent drying, foaming, and cooling stages to become foam glass aggregate.

[0052] During operation, the powder mixture adheres to the inner walls and edges of the disc. The scraper promptly removes this adhered material and returns it to the material flow within the disc, preventing excessive accumulation at the disc edge and ensuring the proper granulation process. Furthermore, the scraper, through contact and agitation with the material, can intervene in the particle growth process. If particles are too large, the scraping action of the scraper can break them into smaller particles, bringing them within the product's particle size requirements. Furthermore, the scraper can also cause small particles to collide and agglomerate, accelerating particle growth and reducing them to the desired particle size range.

[0053] According to the method of the present invention, the size of the foam glass aggregate produced is 10-20 mm and the bulk density is about 580 kg / m 3 , particle density is about 1100kg / m 3 The particle compressive strength is about 9.93MPa. Table 1 lists the comparison with similar products.

[0054] Table 1. Compressive strength and particle size of foam glass aggregate

[0055] Aggregate Source Dimensions (mm) Strength (MPa) Foam glass aggregate 10-20 9.93 (1.85)* Commercial Products 8-16 1.00 Academic Paper #1 12.5 0.51 Academic Paper #2 10-15 2.1

[0056] *Mean (standard deviation)

[0057] According to the results provided, the foam glass aggregate produced by the present invention can be used as a lightweight coarse aggregate in concrete.

[0058] Next, an embodiment of a method for preparing concrete using the foam glass aggregate prepared by the present invention is introduced.

[0059] The method for preparing a concrete product containing foam glass aggregate comprises the following steps in sequence:

[0060] (1) Material preparation: Cement with the trade name CEM1 52.5N, which is available from Green Island Cement Company, is used in an amount of 420 kg / m 3 , foam glass aggregate, dosage 427kg / m 3 , fine river sand aggregate, dosage 753.1kg / m 3 , tap water, dosage 189kg / m 3 The foam glass is a foam glass aggregate prepared according to the present invention, with a size of 10-20 mm and a bulk density of 580 kg / m 3 , particle density is 1100kg / m 3 .

[0061] (2) Mix the aforementioned cement, fine river sand aggregate and tap water and stir evenly to form mortar.

[0062] (3) In an environment with a temperature of 23°C, foam glass aggregate is added to the mortar and stirred at a low speed to form concrete.

[0063] (4) Pour the concrete into the mold in a closed room at an ambient temperature of 23°C and vibrate on a vibration table for 2-3 minutes. The so-called closed room refers to a room with poor air flow, preferably one that cannot be felt by humans. The mold used is a cubic container with a side length of 100 mm.

[0064] (5) Place the mold in a cool place at 23°C for 24 hours, then remove the mold to form the finished product 1. The finished product 1 is placed in a cool place at 23°C for 28 days.

[0065] Effect Description

[0066] After curing, three pieces of the finished product 1 were tested for dry density, thermal conductivity, and compressive strength. The dry density was 2002.9 kg / m³, the thermal conductivity was 1.2520 W / mK, and the compressive strengths after 7 and 28 days of curing were 40.9 MPa and 51.7 MPa, respectively. A comparison of the performance parameters of the resulting concrete with those of conventional concrete (see Table 2) indicates that the resulting concrete is lightweight and possesses excellent thermal insulation properties. The 28-day compressive strength of the resulting concrete exceeded 50 MPa, demonstrating sufficient mechanical strength for use in structural components. Regarding the manufacturing cost of the concrete, although the use of foam glass aggregate in the resulting concrete results in higher initial production costs than crushed stone aggregate used in conventional concrete, the performance comparison in Table 2 demonstrates that the use of foam glass aggregate reduces concrete density, thereby reducing transportation and construction pumping costs. Furthermore, the foam glass aggregate reduces the thermal conductivity of the concrete, which can reduce heat conduction in buildings, reduce the use of air conditioning, and save electricity costs. Therefore, although the initial cost of the produced concrete is higher than that of ordinary concrete, from the perspective of the building's service life cycle of several decades, the economic benefits brought by its low density and low thermal conductivity will be better than using ordinary concrete.

[0067] Table 2. Performance parameter comparison

[0068] parameter The prepared concrete Ordinary concrete Dry density <![CDATA[2002.9kg / m 3 ]]> <![CDATA[~2400kg / m 3 ]]> Thermal conductivity 1.2520W / mk 1.4~2.5W / mk

[0069] In addition, the present invention also provides a high-strength lightweight aggregate preparation system, which includes a grinding device for crushing soda-lime glass into fine glass powder; a screening device for screening the fine glass powder to obtain glass powder within a predetermined size range; a mixing device for fully mixing the glass powder with a foaming agent to obtain a powder mixture; a disc granulator, the powder mixture is put into the disc of the disc granulator and moves within the disc; a spraying device for regularly spraying a binder onto the powder mixture in the disc, the powder mixture producing particles under the action of the binder; an oven for dehydrating the particles; and a muffle furnace, which can raise and lower the temperature according to a predetermined program so that the particles foam in the muffle furnace and form foamed glass aggregate.

[0070] The above description of the present invention is provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. For those skilled in the art, many modifications and variations will be apparent.

[0071] The embodiment was chosen and described in order to best explain the principles of the invention and its practical application, thereby enabling others skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use contemplated.

Claims

1. A method for preparing high-strength lightweight aggregate for concrete production, the method comprising: crushing soda lime glass into fine glass powder; screening the glass powder to obtain glass powder particles having a size within a predetermined size range; The sieved glass powder particles and limestone powder are thoroughly mixed to obtain a uniformly distributed powder mixture; transferring the powder mixture to a disc granulator; Turning on the disc granulator and periodically spraying the sodium silicate solution onto the powder mixture to produce granules; Dehydrating the produced granules in an oven; placing the dried particles on a setter plate in a muffle furnace, wherein all the particles are spaced apart; The particles are subjected to a temperature program for carrying out the foaming process.

2. The method according to claim 1, wherein The mass ratio of the glass powder to the limestone powder is 100:

3.

3. The method according to claim 1, wherein The produced granules were dried at 90°C for 2 hours.

4. The method according to claim 1, wherein the disc inclination angle of the disc granulator is set to 45° from the normal line and the rotation speed thereof is 30 rpm.

5. The method according to claim 1, wherein The temperature program is set as follows: The muffle furnace was heated from room temperature to 250° C. at a rate of 5° C. / min; Maintaining the temperature of the muffle furnace at 250° C. for 20 minutes to preheat and uniformly heat the particles; Raising the temperature of the muffle furnace from 250° C. to 850° C. at a rate of 5° C. / min to reach the foaming temperature; The temperature of the muffle furnace was maintained at 850° C. for 30 minutes to promote the foaming process; Cooling the muffle furnace from 850° C. to 600° C. at a rate of 10° C. / min; The temperature of the muffle furnace was maintained at 600° C. for 20 minutes to stabilize the pores generated in the foam particles; as well as The muffle furnace was naturally cooled from 600° C. to room temperature to eliminate residual stress in the foam particles.

6. The method according to claim 1, wherein The size of the glass powder is 30 to 80 mesh, and the size of the limestone powder is about 8000 mesh.

7. The method according to claim 1, wherein The chemical formula of the sodium silicate solution is Na2O•3.4SiO2•H2O.

8. A high-strength lightweight aggregate for concrete products, characterized in that: The aggregate is obtained by the preparation method according to any one of claims 1 to 7, wherein the size of the aggregate is 10 mm to 20 mm and the bulk density is about 580 kg / m 3 , particle density is about 1100kg / m 3 , the compressive strength of the particles is about 9.93MPa.

9. A concrete, the raw material components of which include: Cement, dosage is 420kg / m 3 ; Foam glass aggregate, dosage is 427kg / m 3 ; Fine river sand aggregate, dosage is 753.1kg / m 3 ;Tap water, dosage is 189kg / m 3 , characterized in that the foam glass aggregate is the high-strength lightweight aggregate as described in claim 8.

10. A high-strength lightweight aggregate preparation system for concrete products, characterized in that: The system includes: a grinding device for crushing soda-lime glass into fine glass powder; a screening device for screening the fine glass powder to obtain glass powder within a predetermined size range; a mixing device for thoroughly mixing the glass powder with a foaming agent to obtain a powder mixture; a disc granulator, wherein the powder mixture is put into a disc of the disc granulator and moves within the disc; a spraying device for periodically spraying a binder onto the powder mixture in the disk, wherein the powder mixture generates particles under the action of the binder; an oven for dehydrating the particles; The muffle furnace can be heated and cooled according to a predetermined program so that the particles can foam in the muffle furnace and form foam glass aggregate.

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