Preparation method of early-strength carbon-reduced lightweight aggregate cement-based material

Abstract

The application relates to the field of cement material preparation, and particularly discloses a preparation method of an early-strength carbon-reduction light aggregate cement-based material, which comprises the following steps: (1) mixing emulsified asphalt, a silane coupling agent and polyethylene glycol powder to form a coating agent. Then, the coating agent is added to volcanic light aggregate while stirring, and after mixing, recycled concrete powder is added to coat the surface of the aggregate. After solidification, the excess powder is removed through screening to obtain pretreated light aggregate. (2) After the pretreated light aggregate is sprayed with water and moistened, the light aggregate is placed in a sealed container, carbon dioxide is introduced, and heating and insulation are performed, so that the reprocessed light aggregate is obtained. (3) cement, sand fine aggregate, the pretreated light aggregate, an anti-shrinkage agent, glass powder and a water reducing agent are uniformly mixed as raw materials, and then water is added and uniformly stirred, so that the cement-based material is obtained. The cement-based material not only has good fluidity and early strength, but also can prevent mechanical strength deterioration caused by later drying shrinkage.

Description

A method for preparing early-strength, low-carbon lightweight aggregate cementitious materials Technical Field

[0001] This invention relates to the field of cement material preparation, specifically to a method for preparing an early-strength, low-carbon, lightweight aggregate cement-based material. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] In an era where the construction industry pursues energy conservation and sustainability, lightweight concrete materials, with their unique properties, have demonstrated enormous potential in terms of thermal insulation, energy saving, and ease of construction, becoming an indispensable and important component in modern architecture. For example, using lightweight aggregate concrete blocks to construct infill walls and partitions in frame structures not only significantly reduces the wall's self-weight but also provides excellent thermal insulation and soundproofing. Thermal insulation slope layers or precast roof insulation panels constructed with lightweight concrete materials not only reduce roof loads but also achieve excellent thermal insulation performance due to their porous structure, effectively reducing building energy consumption. Furthermore, the porous structure of lightweight concrete gives it sound-absorbing properties, making it suitable for theaters, recording studios, computer rooms, and other places where reverberation time control is crucial. This building material, with its unique properties, has become one of the key materials for the transformation of modern architecture towards lightweighting, industrialization, and green building practices.

[0004] The core characteristic of lightweight concrete lies in its low density. One of its preparation techniques involves using natural or artificial lightweight aggregates (such as pumice, expanded clay, expanded shale, and recycled aggregates made from waste concrete) to completely or partially replace traditional sand and gravel. These aggregates are porous, giving the concrete its lightweight properties and often improving its thermal insulation performance. However, due to the porous nature of these lightweight aggregates, their water absorption rate is much higher than that of sand and gravel aggregates. This causes the aggregates to absorb water rapidly during mixing, significantly reducing the fluidity of cementitious materials. This affects construction and also the early hydration of the cement, leading to insufficient early strength development. Furthermore, later water evaporation causes the concrete to exhibit significantly greater drying shrinkage and creep than ordinary cementitious materials, easily inducing the formation of microcracks and resulting in a decrease in the mechanical strength of the cement structure. Summary of the Invention

[0005] This invention discloses a method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material. This cementitious material not only has good fluidity and early strength, but also prevents mechanical strength degradation caused by later drying shrinkage. Specifically, the technical solution of this invention is as follows.

[0006] A method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material includes the following steps:

[0007] (1) Emulsified asphalt, silane coupling agent and polyethylene glycol powder are mixed to form a coating agent. Then, the coating agent is added to the volcanic rock lightweight aggregate while stirring. After mixing, recycled concrete micro powder is added to coat the surface of the aggregate. After curing, the excess micro powder is removed by sieving to obtain pretreated lightweight aggregate.

[0008] (2) After the pretreated lightweight aggregate is moistened by spraying water, it is placed in a sealed container, and then carbon dioxide is introduced and heated and kept warm. After completion, the retreated lightweight aggregate is obtained.

[0009] (3) The waste microbial cells from citric acid fermentation are dried, then mixed with silica fume and ground to obtain a composite powder. The composite powder is then dispersed in anhydrous ethanol solution containing stearic acid and spray-dried to obtain an anti-shrinkage agent.

[0010] (4) After mixing cement, sand, fine aggregate, the pretreated lightweight aggregate, glass powder, the anti-shrinkage agent, and water-reducing agent, add water and mix well to obtain the cement-based material.

[0011] Further, in step (1), the ratio of emulsified asphalt, silane coupling agent, and polyethylene glycol powder is 1~1.4g: 0.07~0.085g: ​​0.12~0.15g. Optionally, the silane coupling agent includes at least one of KH550, KH560, KH570, A171, KH792, etc.

[0012] Further, in step (1), the ratio of the volcanic rock lightweight aggregate to the coating agent is 1g:0.2~0.23g.

[0013] Further, in step (1), the ratio of the volcanic rock lightweight aggregate to the recycled concrete powder is 1g:0.6~0.8g.

[0014] Further, in step (2), the ratio of the pretreated lightweight aggregate to water is 1g:0.35~0.5g. Optionally, the particle size of the retreated lightweight aggregate is 8~12mm.

[0015] Furthermore, in step (2), the volume percentage of carbon dioxide in the sealed container is 20-30%.

[0016] Furthermore, in step (2), the heating temperature is 40~45℃ and the heat preservation time is 7~10 hours.

[0017] Furthermore, in step (3), the ratio of the waste microbial cells to silica fume is 1g:1.5~1.8g.

[0018] Further, in step (3), the ratio of the composite powder to the anhydrous ethanol solution containing stearic acid is 1g:5~10mL. Optionally, the fineness of the powder is 200~300 mesh.

[0019] Furthermore, in step (3), the mass fraction of stearic acid in the anhydrous ethanol solution is 10-15%.

[0020] Further, in step (4), the proportions of cement, sand, fine aggregate, pretreated lightweight aggregate, glass powder, anti-shrinkage agent, water-reducing agent, and water are 105~115 parts by weight: 130~150 parts by weight: 210~240 parts by weight: 10~15 parts by weight: 15~25 parts by weight: 0.52~0.95 parts by weight: 42~49 parts by weight.

[0021] Furthermore, in step (4), the glass powder has a fineness of 300-400 mesh.

[0022] Further, in step (4), the water-reducing agent includes at least one of the following: polycarboxylate water-reducing agent, naphthalene water-reducing agent, lignin sulfonate water-reducing agent, aliphatic water-reducing agent, etc.

[0023] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0024] (1) To address the problem that lightweight aggregates can easily affect the workability and strength of cement-based materials, this invention first uses a novel coating agent system composed of emulsified asphalt, silane coupling agent, and polyethylene glycol to form a coating layer on the surface of volcanic rock lightweight aggregates. The coupling agent can effectively enhance the bonding force between the coating layer and the aggregate, improving the mechanical strength of the cement-based material. The polyethylene glycol helps to improve the low-temperature toughness of the coating layer and enhance its low-temperature crack resistance. Then, the coating agent is used to coat the recycled concrete powder layer, and finally, carbon dioxide is used for treatment. Thus, on the one hand, the coating layer reduces the problem of high water absorption of the aggregate, enabling the prepared cement-based material to have good flow energy, allowing the early hydration reaction to proceed fully, and ensuring good early strength. On the other hand, the large amount of Ca(OH)2 and CSH contained in the recycled concrete powder reacts with carbon dioxide to fix carbon. Simultaneously, during this process, the polyethylene glycol on the surface of the coating layer dissolves in water, which not only promotes the formation of calcium carbonate whiskers in the reaction, but also helps prevent the aggregation of calcium carbonate whiskers after the coupling agent in the coating layer dissolves in water. The micropores formed on the surface of the coating layer after the polyethylene glycol dissolves in water can promote the release of more coupling agent. In addition, the acidic environment formed by carbon dioxide also helps the coupling agent in the coating layer to be released, thereby realizing the reuse of the coupling agent. Since the reprocessed lightweight aggregate prepared by this invention contains a large number of uniformly dispersed calcium carbonate whiskers on its surface, the cement-based material prepared using it can not only form more hydration cementitious products at the aggregate-matrix interface under the induction of the calcium carbonate whiskers, but also interweave with the whiskers to form a network, which can effectively improve the interfacial bonding force and improve the mechanical strength of the cement-based material.

[0025] (2) In this invention, an anti-shrinkage agent is obtained by coating the waste microorganisms from citric acid fermentation and silica fume composite particles with a coating layer formed by stearic acid. This is then added to the cement-based material of this invention. First, the stearic acid coating layer prevents the anti-shrinkage agent from taking effect prematurely in the early stages of cement hydration. As the hydration reaction continues, the stearic acid coating layer gradually decomposes and releases water under the action of the hydration product calcium hydroxide. This not only replenishes the decreasing free water in the system, but also allows the water to enter the anti-shrinkage agent, causing the waste microorganisms to release organic acids such as citric acid. The abundant carboxyl groups in these acids react with the calcium hydroxide to release more water, thus continuously replenishing water in the later stages of the hydration reaction. This not only promotes the development of the later hydration reaction and improves the later strength of the cement-based material of this invention, but also helps prevent the deterioration of mechanical strength caused by later drying shrinkage. Simultaneously, the calcium hydroxide entering the anti-shrinkage agent reacts with silica fume to form hydrated calcium silicate, thereby transforming the low-strength anti-shrinkage agent into a high-strength cementitious product, which helps improve the mechanical strength of the cement-based material. Attached Figure Description

[0026] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein:

[0027] Figure 1 shows the sample images of the reprocessed lightweight aggregate (a), the anti-shrinkage agent (b), and the compressive strength (c) of the sample prepared in Example 1 below.

[0028] Figure 2 shows the sample images of the reprocessed lightweight aggregate (a), the anti-shrinkage agent (b), and the compressive strength (c) of the samples prepared in Example 2 below.

[0029] Figure 3 shows the sample images of the reprocessed lightweight aggregate (a), the anti-shrinkage agent (b), and the compressive strength (c) of the samples prepared in Example 3 below.

[0030] Figure 4 shows the sample of reprocessed lightweight aggregate prepared in Example 4 below (a) and the compressive strength test diagram (b).

[0031] Figure 5 shows the sample of reprocessed lightweight aggregate prepared in Example 5 below (a) and the compressive strength test diagram (b).

[0032] Figure 6 shows the sample of reprocessed lightweight aggregate prepared in Example 6 below (a) and the compressive strength test diagram (b).

[0033] Figure 7 shows the compressive strength test results of Example 7 below.

[0034] Figure 8 shows the sample of the anti-shrinkage agent prepared in Example 8 below (a) and the compressive strength test diagram (b). Detailed Implementation

[0035] The present invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention.

[0037] Example 1: A method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material, comprising the following steps:

[0038] (1) Emulsified asphalt, silane coupling agent (KH550), and polyethylene glycol powder (PEG2000) were mixed in a mass ratio of 1.25g:0.08g:0.14g and stirred evenly to obtain a coating agent. Then, the coating agent was sprayed onto the volcanic rock lightweight aggregate while stirring, with a ratio of 1g:0.2g. After mixing, the volcanic rock lightweight aggregate and recycled concrete micro powder with a fineness of 350 mesh were added to coat the surface of the aggregate. After curing, the excess micro powder was removed by sieving to obtain pretreated lightweight aggregate.

[0039] (2) Under stirring conditions, the pretreated lightweight aggregate was sprayed with water to wet it at a ratio of 1g:0.4g. The resulting wet aggregate was then placed in a carbonization box, and carbon dioxide was introduced and heated to 45°C for 8.5 hours. During this period, the volume percentage of carbon dioxide in the carbonization box was set to 20%. After completion, the aggregate was dried and sieved to obtain reprocessed lightweight aggregate with a particle size distribution between 8 and 12 mm (as shown in Figure 1a).

[0040] (3) Dry the waste microbial body from citric acid fermentation, then mix it with silica fume at a ratio of 1g:1.6g and grind it, then pass it through a 300-mesh sieve to obtain composite powder.

[0041] (4) After heating the anhydrous ethanol solution to 75°C, add stearic acid and stir until dissolved to form an anhydrous ethanol solution with a stearic acid mass fraction of 10%. Then, mix the composite powder with the anhydrous ethanol solution at a ratio of 1g:8mL and stir evenly. Then, dry the mixture to obtain the anti-shrinkage agent (as shown in Figure 1b).

[0042] (5) Take the following components in the following proportions: 110 parts by weight of 42.5 ordinary Portland cement, 138 parts by weight of river sand, 225 parts by weight of the reprocessed lightweight aggregate of this embodiment, 12 parts by weight of waste glass powder, 20 parts by weight of the anti-shrinkage agent of this embodiment, and 0.65 parts by weight of polycarboxylate superplasticizer, wherein the particle size of the river sand is between 0.4 and 1 mm, and the fineness of the waste glass powder is 350 mesh. After mixing the above components evenly, add 46.2 parts by weight of water and stir for 2 minutes to obtain the cement-based material.

[0043] Performance testing: (1) The fluidity of the cement-based material prepared in this embodiment was tested according to the "Method for Determination of Flowability of Cement Mortar" (GBT2419-2005). (2) The cement-based material prepared in this embodiment was poured into a mold, hardened, demolded, and cured for 3 days and 28 days respectively to obtain 3-day and 28-day specimens. Then, the compressive strength of the 3-day specimen was tested according to the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GBT 50081-2019) (as shown in Figure 1c). In addition, the 28-day specimen was frozen at -10℃ for 24 hours, and then its compressive strength was tested according to the above standard. The results are shown in the table below:

[0044]

[0045] Example 2: A method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material, comprising the following steps:

[0046] (1) Emulsified asphalt, silane coupling agent (KH792), and polyethylene glycol powder (PEG1500) were mixed in a mass ratio of 1.0g:0.07g:0.12g and stirred evenly to obtain a coating agent. Then, the coating agent was sprayed onto the volcanic rock lightweight aggregate while stirring, with a ratio of 1g:0.23g. After mixing, the volcanic rock lightweight aggregate and recycled concrete micro powder with a fineness of 300 mesh were added to coat the surface of the aggregate. After curing, the excess micro powder was removed by sieving to obtain pretreated lightweight aggregate.

[0047] (2) Under stirring conditions, the pretreated lightweight aggregate was sprayed with water to wet it at a ratio of 1g:0.35g. The resulting wet aggregate was then placed in a carbonization box, and carbon dioxide was introduced and heated to 40°C for 10 hours. During this period, the volume percentage of carbon dioxide in the carbonization box was set to 25%. After completion, the aggregate was dried and sieved to obtain reprocessed lightweight aggregate with a particle size distribution between 8 and 12 mm (as shown in Figure 2a).

[0048] (3) Dry the waste microbial body from citric acid fermentation, then mix it with silica fume at a ratio of 1g:1.8g and grind it, then pass it through a 300-mesh sieve to obtain composite powder.

[0049] (4) After heating the anhydrous ethanol solution to 75°C, add stearic acid and stir until dissolved to form an anhydrous ethanol solution with a stearic acid mass fraction of 15%. Then, mix the composite powder with the anhydrous ethanol solution at a ratio of 1g:5mL and stir evenly. Then, dry the mixture to obtain the anti-shrinkage agent (as shown in Figure 2b).

[0050] (5) Take the following components in the following proportions: 105 parts by weight of 42.5 ordinary Portland cement, 130 parts by weight of river sand, 210 parts by weight of the reprocessed lightweight aggregate of this embodiment, 10 parts by weight of waste glass powder, 15 parts by weight of the anti-shrinkage agent of this embodiment, and 0.52 parts by weight of polycarboxylate superplasticizer, wherein the particle size of the river sand is between 0.4 and 1 mm, and the fineness of the waste glass powder is 300 mesh. After mixing the above components evenly, add 42 parts by weight of water and stir for 2 minutes to obtain the cement-based material.

[0051] Performance testing: The flowability, 3-day compressive strength (as shown in Figure 2c), and 28-day compressive strength of the cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results are shown in the table below:

[0052]

[0053] Example 3: A method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material, comprising the following steps:

[0054] (1) Emulsified asphalt, silane coupling agent (KH570), and polyethylene glycol powder (PEG2000) were mixed in a mass ratio of 1.4g:0.085g:0.15g and stirred evenly to obtain a coating agent. Then, the coating agent was sprayed onto the volcanic rock lightweight aggregate while stirring, with a ratio of 1g:0.22g. After mixing, the volcanic rock lightweight aggregate and recycled concrete micro powder with a fineness of 300 mesh were added to coat the surface of the aggregate. After curing, the excess micro powder was removed by sieving to obtain pretreated lightweight aggregate.

[0055] (2) Under stirring conditions, the pretreated lightweight aggregate was sprayed with water to wet it at a ratio of 1g:0.5g. The resulting wet aggregate was then placed in a carbonization box, and carbon dioxide was introduced and heated to 45°C for 7 hours. During this period, the volume percentage of carbon dioxide in the carbonization box was set to 30%. After completion, the aggregate was dried and sieved to obtain reprocessed lightweight aggregate with a particle size distribution between 8 and 12 mm (as shown in Figure 3a).

[0056] (3) Dry the waste microbial body from citric acid fermentation, then mix it with silica fume at a ratio of 1g:1.5g and grind it, then pass it through a 200-mesh sieve to obtain composite powder.

[0057] (4) After heating the anhydrous ethanol solution to 75°C, add stearic acid and stir until dissolved to form an anhydrous ethanol solution with a stearic acid mass fraction of 10%. Then, mix the composite powder with the anhydrous ethanol solution at a ratio of 1g:10mL and stir evenly. Then, dry the mixture to obtain the anti-shrinkage agent (as shown in Figure 3b).

[0058] (5) Take the following components in the following proportions: 115 parts by weight of 42.5 ordinary Portland cement, 150 parts by weight of river sand, 240 parts by weight of the reprocessed lightweight aggregate of this embodiment, 15 parts by weight of waste glass powder, 25 parts by weight of the anti-shrinkage agent of this embodiment, and 0.95 parts by weight of naphthalene-based water-reducing agent, wherein the particle size of the river sand is between 0.4 and 1 mm, and the fineness of the waste glass powder is 400 mesh. After mixing the above components evenly, add 49 parts by weight of water and stir for 2 minutes to obtain the cement-based material.

[0059] Performance testing: The flowability, 3-day compressive strength (as shown in Figure 3c), and 28-day compressive strength of the cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results are shown in the table below:

[0060]

[0061] Example 4: A method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material, the same as in Example 1 above, except that the reprocessed lightweight aggregate in this example is prepared using the following method:

[0062] (1) Emulsified asphalt and polyethylene glycol powder (PEG2000) were mixed at a mass ratio of 1.25g:0.14g and stirred evenly to obtain a coating agent. Then, the coating agent was sprayed onto the volcanic rock lightweight aggregate while stirring, with a ratio of 1g:0.2g. After mixing, the volcanic rock lightweight aggregate and recycled concrete micro powder with a fineness of 350 mesh were added to coat the surface of the aggregate. After curing, the excess micro powder was removed by sieving to obtain pretreated lightweight aggregate.

[0063] (2) Under stirring conditions, the pretreated lightweight aggregate was sprayed with water to wet it at a ratio of 1g:0.4g. The resulting wet aggregate was then placed in a carbonization box, and carbon dioxide was introduced and heated to 45°C for 8.5 hours. During this period, the volume percentage of carbon dioxide in the carbonization box was set to 20%. After completion, the aggregate was dried and sieved to obtain reprocessed lightweight aggregate with a particle size distribution between 8 and 12 mm (as shown in Figure 4a).

[0064] Performance testing: The flowability, 3-day compressive strength (as shown in Figure 4b), and 28-day compressive strength of the cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results are shown in the table below:

[0065]

[0066] Example 5: A method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material, similar to Example 2 above, except that the reprocessed lightweight aggregate in this example is prepared using the following method:

[0067] (1) Emulsified asphalt and silane coupling agent (KH792) are mixed at a mass ratio of 1.0g:0.07g and stirred evenly to obtain a coating agent. Then, the coating agent is sprayed onto the volcanic rock lightweight aggregate while stirring, with a ratio of 1g:0.23g. After mixing, the volcanic rock lightweight aggregate and recycled concrete micro powder with a fineness of 300 mesh are added to coat the surface of the aggregate. After curing, the excess micro powder is removed by sieving to obtain pretreated lightweight aggregate.

[0068] (2) Under stirring conditions, the pretreated lightweight aggregate was sprayed with water to moisten it at a ratio of 1g:0.35g. The resulting wet aggregate was then placed in a carbonization box, and carbon dioxide was introduced and heated to 40°C for 10 hours. During this period, the volume percentage of carbon dioxide in the carbonization box was set to 25%. After completion, the aggregate was dried and sieved to obtain reprocessed lightweight aggregate with a particle size distribution between 8 and 12 mm (as shown in Figure 5a).

[0069] Performance testing: The flowability, 3-day compressive strength (as shown in Figure 5b), and 28-day compressive strength of the cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results are shown in the table below:

[0070]

[0071] Example 6: A method for preparing an early-strength, low-carbon lightweight aggregate cementitious material, the same as in Example 3 above, except that the reprocessed lightweight aggregate in this example is prepared using the following method:

[0072] (1) Emulsified asphalt, silane coupling agent (KH570), and polyethylene glycol powder (PEG2000) were mixed in a mass ratio of 1.4g:0.085g:0.15g and stirred evenly to obtain a coating agent. Then, the coating agent was sprayed onto the volcanic rock lightweight aggregate while stirring, with a ratio of 1g:0.22g. After mixing, the volcanic rock lightweight aggregate and recycled concrete micro powder with a fineness of 300 mesh were added to coat the surface of the aggregate. After curing, the excess micro powder was removed by sieving to obtain pretreated lightweight aggregate.

[0073] (2) Under stirring conditions, the pretreated lightweight aggregate was sprayed with water to wet it at a ratio of 1g:0.5g. The resulting wet aggregate was then placed in a carbonization box and heated to 45°C for 7 hours without introducing carbon dioxide. After completion, the aggregate was dried and sieved to obtain reprocessed lightweight aggregate with a particle size distribution between 8 and 12 mm (as shown in Figure 6a).

[0074] Performance testing: The flowability, 3-day compressive strength (as shown in Figure 6b), and 28-day compressive strength of the cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results are shown in the table below:

[0075]

[0076] Example 7: A method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material, comprising the following steps:

[0077] The following components were prepared in the following proportions: 105 parts by weight of 42.5 ordinary Portland cement, 130 parts by weight of river sand, 210 parts by weight of the reprocessed lightweight aggregate from Example 2 above, 10 parts by weight of waste glass powder, and 0.52 parts by weight of polycarboxylate superplasticizer. The river sand had a particle size distribution between 0.4 and 1 mm, and the waste glass powder had a fineness of 300 mesh. After mixing all the components thoroughly, 42 parts by weight of water were added and stirred for 2 minutes to obtain the cement-based material.

[0078] Performance testing: The flowability, 3-day compressive strength (as shown in Figure 7), and 28-day compressive strength of the cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results are shown in the table below:

[0079]

[0080] Example 8: A method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material, the same as in Example 3 above, except that the anti-shrinkage agent in this example is prepared by the following method:

[0081] (1) Dry the waste microbial cells from citric acid fermentation, then mix them with silica fume at a ratio of 1g:1.5g and grind them. Then pass them through a 200-mesh sieve to obtain an anti-shrinkage agent (as shown in Figure 8a).

[0082] (2) Take the following components in the following proportions: 115 parts by weight of 42.5 ordinary Portland cement, 150 parts by weight of river sand, 240 parts by weight of the reprocessed lightweight aggregate of Example 3 above, 15 parts by weight of waste glass powder, 25 parts by weight of the anti-shrinkage agent of this example, and 0.95 parts by weight of naphthalene-based water-reducing agent, wherein the particle size of the river sand is between 0.4 and 1 mm, and the fineness of the waste glass powder is 400 mesh. After mixing the above components evenly, add 49 parts by weight of water and stir for 2 minutes to obtain the cement-based material.

[0083] Performance testing: The flowability, 3-day compressive strength (as shown in Figure 8b), and 28-day compressive strength of the cement-based material prepared in this embodiment were tested using the same method as in Example 1 above. The results are shown in the table below:

[0084]

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an early-strength, low-carbon, lightweight aggregate cementitious material, characterized in that, The process includes the following steps: (1) Mixing emulsified asphalt, silane coupling agent, and polyethylene glycol powder in a ratio of 1~1.4g: 0.07~0.085g: ​​0.12~0.15g to form a coating agent; then adding the coating agent to the volcanic rock lightweight aggregate while stirring, mixing well, and then adding recycled concrete micro powder to coat the surface of the aggregate. After curing, sieving to remove excess micro powder to obtain pretreated lightweight aggregate; (2) Wetting the pretreated lightweight aggregate with water and placing it in a sealed container, then ventilating... Carbon dioxide is introduced and heated and kept warm. After completion, reprocessed lightweight aggregate is obtained; (3) The waste bacteria of citric acid fermentation are dried, and then mixed with silica fume at a ratio of 1g:1.5~1.8g and ground to obtain composite powder; then the composite powder is dispersed in anhydrous ethanol solution containing stearic acid for spray drying treatment to obtain anti-shrinkage agent; (4) Cement, sand fine aggregate, the reprocessed lightweight aggregate, glass powder, the anti-shrinkage agent and water-reducing agent are mixed and then water is added and mixed to obtain the cement-based material.

2. The preparation method of the early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (1), the ratio of the volcanic rock lightweight aggregate to the coating agent is 1g:0.2~0.23g.

3. The preparation method of the early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (1), the silane coupling agent includes at least one of KH550, KH560, KH570, A171, and KH792.

4. The preparation method of the early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (1), the ratio of the volcanic rock lightweight aggregate to the recycled concrete powder is 1g:0.6~0.8g.

5. The method for preparing early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (2), the ratio of the pretreated lightweight aggregate to water is 1g:0.35~0.5g.

6. The method for preparing early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (2), the particle size of the reprocessed lightweight aggregate is 8~12mm.

7. The method for preparing early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (2), the volume percentage of carbon dioxide in the sealed container is 20-30%.

8. The method for preparing early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (2), the heating temperature is 40~45℃ and the heat preservation time is 7~10 hours.

9. The preparation method of the early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (3), the ratio of the composite powder to the anhydrous ethanol solution containing stearic acid is 1g: 5~10mL.

10. The method for preparing early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (3), the fineness of the composite powder is 200~300 mesh.

11. The method for preparing early-strength, low-carbon, lightweight aggregate cementitious material according to claim 1, characterized in that, In step (3), the mass fraction of stearic acid in the anhydrous ethanol solution is 10-15%.

12. The method for preparing early-strength, low-carbon, lightweight aggregate cementitious material according to any one of claims 1-11, characterized in that, In step (4), the proportions of cement, sand, fine aggregate, reprocessed lightweight aggregate, glass powder, anti-shrinkage agent, water-reducing agent, and water are 105~115 parts by weight: 130~150 parts by weight: 210~240 parts by weight: 10~15 parts by weight: 15~25 parts by weight: 0.52~0.95 parts by weight: 42~49 parts by weight.

13. The method for preparing early-strength, low-carbon, lightweight aggregate cementitious material according to any one of claims 1-11, characterized in that, In step (4), the glass powder has a fineness of 300-400 mesh.

14. The method for preparing early-strength, low-carbon, lightweight aggregate cementitious material according to any one of claims 1-11, characterized in that, In step (4), the water-reducing agent includes at least one of the following: polycarboxylate water-reducing agent, naphthalene water-reducing agent, lignin sulfonate water-reducing agent, and aliphatic water-reducing agent.

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