A calcined high-silica aluminous-based light-weight foam concrete and a method for preparing the same

Abstract

The present application belongs to the technical field of foam concrete, and discloses a calcined high-silicon aluminum-based light foam concrete and a preparation method thereof. The light foam concrete comprises the following raw materials in mass fraction: 15-30 parts of high-silicon aluminum-based composite calcined material, 20-35 parts of excitation material, 30-45 parts of water, 2-6 parts of modified component, 0.05-0.15 parts of additive, and 0.05-0.2 parts of foaming agent, and the sum of the mass fractions of the above raw materials is 100 parts. The excitation material comprises the following raw materials in mass percentage: 20-35% of limestone powder, 5-15% of gypsum, and 50-80% of ordinary Portland cement. The modified component comprises the following raw materials in mass percentage: 20-40% of sodium sulfate, 15-30% of sodium metaaluminate, and 40-60% of calcium stearate. The light foam concrete has not only good pore stability and high mechanical properties, but also low carbon emissions, and can bring significant economic and environmental benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of foam concrete, and particularly relates to a calcined high-silicon-aluminum-based lightweight foam concrete and a preparation method thereof. Background Art

[0002] Using solid waste as raw material to create new, green, and energy-saving building materials is a key step in the comprehensive utilization of solid waste resources and aligns with the principle of "reduction" in the circular economy. Foamed concrete, due to its lightweight, thermal insulation, fire resistance, sound insulation, and shock absorption properties, is widely used in wall insulation, backfill materials, sandwich components, composite wall panels, and other products. The main challenge in producing lightweight foamed concrete from solid waste is the difficulty in balancing its lightweight and high mechanical strength.

[0003] The most common ways to prepare lightweight foamed concrete are: a) chemical foaming method: a siliceous material (such as siliceous sand) is thoroughly mixed with cement, and a chemical reaction occurs between aluminum powder and a lime-rich substance to generate gas in the mixture slurry, which forms a foam material after hardening; b) physical foaming method: a water-containing foam is prepared by physical methods (by introducing air into a mixture of water and a foaming agent), and the foam is injected into the cement slurry. Finally, the bubbles remain in the hardened cement slurry to form a foam material with uniformly distributed pores.

[0004] Both methods for producing lightweight foamed concrete have their pros and cons. The chemical foaming method produces foamed concrete with superior mechanical properties, but due to its technical complexity and difficulty controlling concrete density, it can generally only be produced in standardized autoclaved aerated concrete plants. The physical foaming method, on the other hand, offers a simpler process and is not restricted by site conditions, making it a popular choice for many construction companies. However, controlling foam stability and concrete strength is difficult, and it can easily lead to mold collapse, which can seriously affect concrete performance.

[0005] Furthermore, the binder used in lightweight foam concrete is often composed primarily of high-CO2-emitting ordinary Portland cement, which accounts for over 50% of the foam concrete's binder weight. Cement production consumes significant amounts of coal resources and releases significant amounts of carbon dioxide greenhouse gases, contributing to resource shortages, exacerbating the greenhouse effect, and polluting the environment. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the deficiencies in the existing technology and provide a calcined high-silicon-aluminum-based lightweight foam concrete and a preparation method thereof. The lightweight foam concrete not only has good pore stability and high mechanical properties, but also has low carbon emissions, which can bring significant economic and environmental benefits.

[0007] To solve the technical problems proposed in the present application, the present application provides a kind of calcined high-silicon aluminum base light foam concrete, including the following mass fraction of raw materials: high-silicon aluminum composite calcined material 15-30 parts, excitation material 20-35 parts, water 30-45 parts, modified component 2-6 parts, additive 0.05-0.15 parts, foaming agent 0.05-0.2 parts, the sum of the mass fraction of the above raw materials is 100 parts.

[0008] In the above scheme, the high-silicon aluminum composite calcined material is obtained by mixing coal gangue, clay and mineralized components into a composite powder and then high-temperature calcining.

[0009] Further, the high-temperature calcining temperature is 550-800℃, the calcining time is 2-3h, and the cooling rate after calcining is 500-600℃ / h.

[0010] Further, the mass percentage of each raw material in the composite powder is: coal gangue 30-65%, clay 30-67%, and mineralized component 2-5%.

[0011] Further, the mineralized component includes the following mass percentage of raw materials: sodium carbonate 10-20%, potassium carbonate 20-50%, and potassium acetate 30-60%.

[0012] Further, the coal gangue is a high-silicon aluminum material associated with coal seams, which is excavated and sorted during coal mining and washing process, and has a chemical SiO2 content of 30-65%, an Al2O3 content of 15-40%, a CaO content of 1-4%, an Fe2O3 content of 2-10%, and an MgO content of 1-3%, and a loss on ignition of 20-30%.

[0013] Further, the clay is a mineral clay material with high silica and alumina content as the main component during mining process, and has a SiO2 content of 40-65%, an Al2O3 content of 15-40%, a CaO content of 0.01-5%, an Fe2O3 content of 0.01-10%, and an MgO content of 0.1-5%.

[0014] Further, the particle size of the coal gangue and clay is less than 80μm, and the sieve residue of 45μm square hole screen is 10-20%, and the specific surface area is 400-600m 2 / kg, and the moisture content is less than 1%.

[0015] In the above scheme, the excitation material includes the following mass percentage of raw materials: limestone powder 20-35%, gypsum 5-15%, and ordinary Portland cement 50-80%.

[0016] Furthermore, the limestone powder is a by-product collected during the production of aggregate or stone, and its main component is calcium carbonate, with a fineness of 5-20% on a 45 μm square hole sieve and a specific surface area of ​​300-500 m 2 / kg, moisture content <1%.

[0017] Furthermore, the gypsum is one or more of natural gypsum, desulfurized gypsum, and fluorinated gypsum.

[0018] In the above scheme, the modified component includes the following raw materials in percentage by mass: 20-40% sodium sulfate, 15-30% sodium metaaluminate, and 40-60% calcium stearate.

[0019] In the above solution, the admixture is polycarboxylate water-reducing agent powder.

[0020] In the above scheme, the foaming agent is an animal or plant protein foaming agent, the foaming multiple is 15 to 30 times, the sedimentation distance in 1 hour is ≤50mm, and the water secretion rate in 1 hour is ≤70%.

[0021] The present invention also provides a method for preparing calcined high-silicon-aluminum-based lightweight foam concrete, which specifically comprises the following steps:

[0022] 1) uniformly mixing the high silicon-aluminum composite calcined material, the excitation material, the modified component and the admixture to obtain a gelling material;

[0023] 2) Mixing the cementitious material and water to obtain concrete slurry;

[0024] 3) diluting the blowing agent in water and then preparing foam in a foaming machine;

[0025] 4) Add the foam to the concrete slurry and mix evenly, then immediately cast into a mold, cure in a standard curing room until solidified, demould, and continue curing to the target age to obtain calcined high-silicon-aluminum-based lightweight foam concrete.

[0026] In the above scheme, the dilution ratio of the foaming agent in step 3) is 30 to 80 times.

[0027] In the above scheme, the foam density prepared in step 3) is 20-60 kg / m 3 .

[0028] In the above scheme, the water amounts in step 2) and step 3) are both included in the concrete formula. The water amount in step 3) is first determined according to the dilution ratio, and the remaining water is then used in step 2).

[0029] In the above scheme, the stirring rate in step 1) is 30-50 r / min, and the stirring time is 2-3 min.

[0030] In the above scheme, the stirring rate in step 2) is 30-50 r / min, and the stirring time is 2-3 min.

[0031] In the above scheme, the stirring rate in step 4) is 20-30 r / min, and the stirring time is 3-5 min.

[0032] In the above scheme, the density of the calcined high-silica aluminous-based light-weight foam concrete is 450-850 kg / m 3 , the 3d strength is 0.2-1.2 MPa, and the 28d strength is 0.5-2 MPa.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] 1) The light-weight foam concrete has good pore stability and high mechanical properties. The cementitious material of the light-weight foam concrete is composed of high-silica aluminous composite calcined material and excitation material. The limestone powder in the excitation material has a small solubility. The dissolved CO3 2- can react with the alumina phase of the high-silica aluminous composite calcined material and the portland cement (derived from the excitation material) to generate monocarbon calcium aluminate (Mc, 3CaO·Al2O3·CaCO3·11H2O) and C-S-H gel and other hydration products generated by the hydration of the portland cement, thereby ensuring the development of the strength of the light-weight foam concrete. In order to avoid the slow early reaction of the cementitious material, a small amount of hydration products cannot support the foam void structure, and the collapse phenomenon is prone to occur. The present application introduces a modified component. The calcium stearate can increase the stability of the foam, and the sodium sulfate and sodium metaaluminate generate aluminum hydroxide gel and ettringite (AFt) in the early hydration of the cementitious material system. The AH gel and the AFt are compounded with the hydration products of the portland cement in the early hydration to make the slurry wrapped around the bubble surface have a certain strength, which has a positive effect on stabilizing the void and preventing the collapse of the light-weight foam concrete. The AH gel reacts with the limestone powder in one day to generate a small amount of monocarbon calcium aluminate, thereby increasing the early strength of the light-weight concrete and allowing the light-weight foam concrete to be demolded in 24 hours, thereby significantly shortening the construction time. The density of the final foam concrete is 450-850 kg / m 3 , the 3d strength can reach 0.2-1.2 MPa, and the 28d strength can reach 0.5-2 MPa.

[0035] 2) The main components of the cementitious material are calcined clay, coal gangue, industrial by-product limestone powder, portland cement, and a small amount of gypsum. The amount of the calcined clay and the coal gangue is close to 50% of the total amount, which reduces the amount of the portland cement and reduces carbon emissions. In addition, a mineralization component is added in the calcination of the clay and the coal gangue, which can reduce the calcination temperature of the material and further reduce carbon emissions. DETAILED DESCRIPTION

[0036] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0037] In the following examples, the clay is a kaolinite clay material produced during mining, the main components of which are silicon oxide and aluminum oxide. Testing revealed that the clay contained 56.1% SiO2, 29.1% Al2O3, 0.4% CaO, 3.1% Fe2O3, and 0.89% MgO. The clay had a particle size of <80 μm, a 45 μm square mesh sieve residue of 15.1%, and a specific surface area of ​​450 m2. 2 / kg, moisture content 0.3%.

[0038] Coal gangue is a waste product from the production processes of coal mining, coal mining, and coal washing. Testing has shown that its SiO2 content is 41.9%, Al2O3 content is 27.6%, CaO content is 1.01%, Fe2O3 content is 2.55%, MgO content is 1.6%, and loss on ignition is 24.6%. Its particle size is less than 80 μm, and the residue on a 45 μm square sieve is 12.8%. Its specific surface area is 480 m2. 2 / kg, moisture content 0.2%.

[0039] Limestone powder is a fine particle collected by dust collector or selected by powder selection equipment during the dry production process of concrete aggregate. Its main component is calcium carbonate. Its fineness is 18.2% on a 45μm square hole sieve, and its specific surface area is 470m 2 / kg, with a moisture content of 0.2%. The admixture is polycarboxylate superplasticizer powder, with a water reduction rate of 23.5%. The foaming agent is Henan Huatai HT composite foaming agent, synthesized from animal and plant proteins, with a foaming multiple of 26, a one-hour settlement distance of 37mm, and a one-hour water bleeding rate of 57%.

[0040] Example 1

[0041] A calcined high-silicon-aluminum-based lightweight foam concrete comprises the following raw materials in parts by mass: 30 parts of high-silicon-aluminum composite calcined material, 29.358 parts of activating material, 36.442 parts of water, 4 parts of modifying component, 0.1 part of admixture, and 0.1 part of foaming agent; wherein the activating material comprises the following raw materials in percentage by mass: 30% of limestone powder, 10% of desulfurized gypsum, and 60% of ordinary Portland cement; and the modifying component comprises the following raw materials in percentage by mass: 30% of sodium sulfate, 20% of sodium metaaluminate, and 50% of calcium stearate.

[0042] The preparation method of the high silicon aluminum composite calcined material is as follows:

[0043] 1) The mineralization components are composed of the following mass percentages: 20% sodium carbonate, 30% potassium carbonate, and 50% potassium acetate;

[0044] 2) The composite powder is composed of the following mass percentages: 42% coal gangue, 54% clay, and 4% mineralized component;

[0045] 3) calcining the composite powder at 800° C. for 2 h, taking it out immediately, and cooling it to room temperature at a cooling rate of 600° C. / h to obtain a high-silicon-aluminum composite calcined material.

[0046] The preparation method of calcined high-silicon-aluminum-based lightweight foamed concrete in this embodiment includes the following steps:

[0047] 1) stirring the high silicon-aluminum composite calcined material, the stimulating material, the modified component and the admixture at a rate of 50 r / min for 2 min to obtain a gelled material;

[0048] 2) Stirring the cementitious material and water (30.442 parts of water) at a rate of 50 r / min for 2 minutes to obtain a concrete slurry;

[0049] 3) Dilute the foaming agent 60 times in water (6 parts water), and then prepare a foam with a density of 40 kg / m 3 of bubbles;

[0050] 4) Add the foam to the concrete slurry and stir at a rate of 20 r / min for 5 minutes, then immediately cast into a mold, and demold after curing in a standard curing room for 1 day. Continue curing to the target age to obtain a calcined high-silicon-aluminum-based lightweight foam concrete.

[0051] Example 2

[0052] A calcined high-silicon-aluminum-based lightweight foam concrete comprises the following raw materials in parts by mass: 27 parts of high-silicon-aluminum composite calcined material, 29.55 parts of an activating material, 38.2 parts of water, 5 parts of a modifying component, 0.1 part of an admixture, and 0.15 parts of a foaming agent; wherein the activating material comprises the following raw materials in percentage by mass: 25% limestone powder, 5% desulfurized gypsum, and 70% ordinary Portland cement; and the modifying component comprises the following raw materials in percentage by mass: 30% sodium sulfate, 20% sodium metaaluminate, and 50% calcium stearate.

[0053] The preparation method of the high silicon aluminum composite calcined material is as follows:

[0054] 1) The mineralization components are composed of the following mass percentages: sodium carbonate 10%, potassium carbonate 40%, and potassium acetate 50%;

[0055] 2) The composite powder is composed of the following mass percentages: 37% coal gangue, 60% clay, and 3% mineralized component;

[0056] 3) calcining the composite powder at 750° C. for 2 h, taking it out immediately, and cooling it to room temperature at a cooling rate of 550° C. / h to obtain a high-silicon-aluminum composite calcined material.

[0057] The preparation method of calcined high-silicon-aluminum-based lightweight foamed concrete in this embodiment includes the following steps:

[0058] 1) stirring the high silicon-aluminum composite calcined material, the stimulating material, the modified component and the admixture at a rate of 50 r / min for 2 min to obtain a gelled material;

[0059] 2) Mixing the cementitious material with water (29.95 parts of water) at a rate of 50 r / min for 2 minutes to obtain a concrete slurry;

[0060] 3) Dilute the foaming agent 55 times in water (8.25 parts of water) and then prepare a foam with a density of 35 kg / m 3 of bubbles;

[0061] 4) Add the foam to the concrete slurry and stir at a rate of 30 r / min for 4 minutes, then immediately cast into a mold, and demold after curing in a standard curing room for 1 day. Continue curing to the target age to obtain a calcined high-silicon-aluminum-based lightweight foam concrete.

[0062] Example 3

[0063] A calcined high-silicon-alumina-based lightweight foam concrete comprises the following raw materials in parts by mass: 28 parts of a high-silicon-alumina composite calcined material, 32 parts of an activating material, 35.3 parts of water, 4.5 parts of a modifying component, 0.097 parts of an admixture, and 0.155 parts of a foaming agent; wherein the activating material comprises the following raw materials in percentage by mass: 20% limestone powder, 10% desulfurized gypsum, and 70% ordinary Portland cement; and the modifying component comprises the following raw materials in percentage by mass: 35% sodium sulfate, 20% sodium metaaluminate, and 45% calcium stearate.

[0064] The preparation method of the high silicon aluminum composite calcined material is as follows:

[0065] 1) The mineralization components are composed of the following mass percentages: sodium carbonate 15%, potassium carbonate 45%, and potassium acetate 40%;

[0066] 2) The composite powder is composed of the following mass percentages: 40% coal gangue, 56% clay, and 4% mineralized component;

[0067] 3) calcining the composite powder at 700° C. for 2 h, taking it out immediately, and cooling it to room temperature at a cooling rate of 550° C. / h to obtain a high-silicon-aluminum composite calcined material.

[0068] The preparation method of the calcined high-silicon aluminous-based light foam concrete in the embodiment comprises the following steps:

[0069] 1) The high-silicon aluminous composite calcined material, the activating material, the modified component and the additive are stirred at a speed of 50 r / min for 3 min to obtain a cementitious material;

[0070] 2) The cementitious material and water (27.55 parts of water) are stirred at a speed of 50 r / min for 3 min to obtain a concrete slurry;

[0071] 3) The foaming agent is diluted 50 times in water (7.75 parts of water), and then a foam with a density of 45 kg / m 3 is prepared in a foaming machine;

[0072] 4) The foam is added to the concrete slurry and stirred at a speed of 20 r / min for 5 min, and then immediately molded, demolded after 1 d of curing in a standard curing room, and continuously cured to a target age to obtain the calcined high-silicon aluminous-based light foam concrete.

[0073] Comparative example

[0074] The difference between the comparative example and the embodiment 1 is that: no mineralization component is added in the preparation process of the high-silicon aluminous composite calcined material, the amount of coal gangue in the composite powder is increased to 46%; and no modified component is added in the raw material of the calcined high-silicon aluminous-based light foam concrete, the amount of the high-silicon aluminous composite calcined material is increased to 32 parts, and the amount of the activating material is increased to 31.358 parts.

[0075] The performance of the light foam concrete in each embodiment and each comparative example is tested, and the results are shown in Table 1.

[0076] Table 1

[0077]

[0078] As can be seen from the table, the technical method of the present application can prepare light foam concrete of different density grades, without the phenomenon of collapse, and can be demolded at 1 d, has a certain early strength, and the strength continuously increases with the increase of the age. In the comparative example, no mineralization component is added in the preparation process of the high-silicon aluminous composite calcined material, which leads to insufficient activation, and the activity of the high-silicon aluminous composite calcined material is reduced, and the cementitious material is not sufficiently hydrated in the early stage. At the same time, no modified component is added in the preparation process of the concrete, which cannot improve the stability of the foam and the early hydration product, and therefore there is a serious phenomenon of collapse, and the concrete cannot be demolded at 1 d.

[0079] The above embodiments are merely exemplary but not intended to limit the present application. Based on the above description, those skilled in the art can make other variations and modifications of the present application without departing from the scope of the present application. Therefore, the intended scope of the present application should be defined by the appended claims.

Claims

1. A calcined high-silicon-aluminum-based lightweight foam concrete, characterized in that: The invention comprises the following raw materials in parts by weight: 15 to 30 parts of high silicon-aluminum composite calcined material, 20 to 35 parts of excitation material, 30 to 45 parts of water, 2 to 6 parts of modified component, 0.05 to 0.15 parts of admixture, and 0.05 to 0.2 parts of foaming agent, and the sum of the parts by weight of the above raw materials is 100 parts; The high-silicon-alumina composite calcined material is prepared by mixing coal gangue, clay, and mineralized components into a composite powder and then calcining it at a high temperature. The mass percentage of each raw material in the composite powder is: coal gangue 30-65%, clay 30-67%, and mineralized components 2-5%. The mass percentage of each raw material in the mineralized components is: sodium carbonate 10-20%, potassium carbonate 20-50%, and potassium acetate 30-60%. The excitation material includes the following raw materials in percentage by mass: 20-35% limestone powder, 5-15% gypsum, and 50-80% ordinary Portland cement; the modified component includes the following raw materials in percentage by mass: 20-40% sodium sulfate, 15-30% sodium metaaluminate, and 40-60% calcium stearate.

2. The calcined high-silicon-alumina-based lightweight foamed concrete according to claim 1, characterized in that: The high-temperature calcination temperature is 550-800° C., the calcination time is 2-3 hours, and the calcination is followed by rapid cooling at a cooling rate of 500-600° C. / h.

3. The calcined high-silicon-alumina-based lightweight foamed concrete according to claim 1, characterized in that: The coal gangue has a SiO2 content of 30-65%, an Al2O3 content of 15-40%, a CaO content of 1-4%, a Fe2O3 content of 2-10%, a MgO content of 1-3%, and a loss on ignition of 20-30%; the clay has a SiO2 content of 40-65%, an Al2O3 content of 15-40%, a CaO content of 0.01-5%, a Fe2O3 content of 0.01-10%, and a MgO content of 0.1-5%; the particle size of the coal gangue and clay are both less than 80 μm, and the residue on a 45 μm square sieve is 10-20%, and the specific surface area is 400-600 m 2 / kg, moisture content <1%.

4. The calcined high-silicon-alumina-based lightweight foamed concrete according to claim 1, characterized in that: The fineness of the limestone powder is 5-20% on a 45 μm square sieve, and the specific surface area is 300-500 m 2 / kg, moisture content <1%; the gypsum is one or more of natural gypsum, desulfurized gypsum, and fluorinated gypsum; the admixture is polycarboxylic acid water-reducing agent powder; the foaming agent is an animal or plant protein foaming agent, with a foaming multiple of 15 to 30 times, a 1-hour settlement distance ≤50 mm, and a 1-hour water seepage rate ≤70%.

5. The calcined high-silicon-alumina-based lightweight foamed concrete according to claim 1, characterized in that: The density of the calcined high-silicon-aluminum-based lightweight foam concrete is 450-850 kg / m 3 , 3d strength is 0.2~1.2MPa, and 28d strength is 0.5~2MPa.

6. A method for preparing a calcined high-silicon-alumina-based lightweight foamed concrete according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) The high silicon-aluminum composite calcined material, the activating material, the modified component and the admixture are uniformly mixed to obtain a gelling material; 2) Mix the cementitious material and water evenly to obtain concrete slurry; 3) diluting the foaming agent in water and then preparing the foam in a foaming machine; 4) Add the foam to the concrete slurry and mix evenly, then immediately cast into a mold, cure in a standard curing room until solidified, demould, and continue curing to the target age to obtain calcined high-silicon-aluminum-based lightweight foam concrete.

7. The method for preparing calcined high-silicon-alumina-based lightweight foamed concrete according to claim 6, characterized in that: In step 3), the dilution ratio of the foaming agent is 30 to 80 times, and the prepared foam density is 20 to 60 kg / m 3 .

8. The method for preparing calcined high-silicon-alumina-based lightweight foamed concrete according to claim 6, wherein: In step 1), the stirring rate is 30-50 r / min, and the stirring time is 2-3 min; in step 2), the stirring rate is 30-50 r / min, and the stirring time is 2-3 min; in step 4), the stirring rate is 20-30 r / min, and the stirring time is 3-5 min.

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