A type of concrete made from recycled aggregate and its preparation method

Abstract

This invention relates to the field of concrete, specifically to a type of concrete prepared from recycled aggregate and its preparation method. The concrete prepared from recycled aggregate comprises: quicklime, modified recycled aggregate, an alkaline activator, silica-reinforcing filler, a water-reducing agent, chopped fibers, and water. The preparation method of the modified recycled aggregate includes: mixing hydroxyethyl acrylate and propyl methacrylate, then adding hydroxypropyl methacrylate and mixing again to obtain a mixed monomer solution; mixing an initiator, nano-silica gel, N,N'-methylenebisacrylamide, and water, adding the mixture to the mixed monomer solution, and reacting to obtain a gel material; mixing the recycled aggregate and the gel material, and curing the mixture to obtain the modified recycled aggregate. By employing specific raw material components and a modified recycled aggregate preparation process, the performance of the recycled aggregate is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of concrete, and more specifically, to a type of concrete made from recycled aggregate and a method thereof. Background Technology

[0002] Large-scale accumulation of construction waste can cause serious pollution to the ecological environment. Using recycled aggregate obtained from waste concrete through a series of processes such as crushing, washing, and grading for concrete production has become an important way to realize the resource utilization of construction waste. However, recycled aggregate has problems such as high water absorption, numerous micro-cracks, and poor durability and bonding properties, which greatly limit its application in concrete engineering. Currently, there are two main methods for processing recycled aggregate: physical strengthening and chemical strengthening. Physical strengthening activates coarse aggregate through mechanical methods, breaking down weak recycled crushed stone particles or removing residual mortar adhering to the recycled crushed stone; chemical strengthening strengthens the transition zone of the recycled concrete interface by adding additives to improve the surface condition of the recycled aggregate. However, these methods still have shortcomings in improving the performance of recycled aggregate, especially the problems of cracks and voids generated during the processing, which lead to high water absorption of recycled aggregate, thus affecting the strength and durability of concrete. Summary of the Invention

[0003] In view of this, the present invention aims to provide concrete prepared from recycled aggregate and its preparation method, so as to solve the problems of high water absorption and numerous micro-cracks in recycled aggregate in the prior art.

[0004] In order to solve the above technical problems, this application is implemented as follows:

[0005] This invention provides a concrete prepared from recycled aggregate, comprising the following components in parts by weight:

[0006] 700-800 parts quicklime, 500-650 parts modified recycled aggregate, 150-160 parts alkaline activator, 200-220 parts silica-reinforcing filler, 7-10 parts water-reducing agent, 15-25 parts chopped fiber and 200-250 parts water;

[0007] The method for preparing the modified recycled aggregate includes the following steps:

[0008] Hydroxyethyl acrylate and methyl methacrylate were mixed, and their neutralization was adjusted with NaOH solution. Then, hydroxypropyl methacrylate was added and mixed to obtain a mixed monomer solution.

[0009] An initiator, nano-silica gel, N,N'-methylenebisacrylamide, and water were mixed, dispersed, and then added to the mixed monomer solution to carry out the reaction, thereby obtaining a gel material.

[0010] Recycled aggregate and gel material are mixed and cured to obtain modified recycled aggregate.

[0011] Preferably, in the concrete prepared from the above-mentioned recycled aggregate, the mass ratio of hydroxyethyl acrylate, propyl methacrylate sulfonate and hydroxypropyl methacrylate is 5-10:2-4:1-2.

[0012] The mass ratio of hydroxyethyl acrylate to initiator is 5–10:0.08–0.12;

[0013] The mass ratio of hydroxyethyl acrylate to nano-silica aerogel is 5-10:4-6;

[0014] The ratio of hydroxyethyl acrylate, N,N'-methylenebisacrylamide, and water is 5-10 g: 0.05-0.1 g: 2.5-5 mL;

[0015] The reaction is carried out by microwave polymerization, with a power of 300-400W and a polymerization time of 2-4 hours.

[0016] Preferably, in the concrete prepared from the above-mentioned recycled aggregate, the mass ratio of the recycled aggregate to the gel material is 1:1 to 3;

[0017] The curing conditions are: temperature 20-30°C, time 12-24 hours, and humidity 50-60%.

[0018] Preferably, in the concrete prepared from the above-mentioned recycled aggregate, the alkaline activator includes fly ash and sodium hydroxide;

[0019] The mass ratio of fly ash to sodium hydroxide is 8-10:1.

[0020] Preferably, in the concrete prepared from the above-mentioned recycled aggregate, the siliceous reinforcing filler includes silica fume modified with an aminosilane coupling agent;

[0021] The water-reducing agent includes polycarboxylate water-reducing agents.

[0022] Preferably, in the concrete prepared from the above-mentioned recycled aggregate, the chopped fibers include at least one of polyvinyl alcohol fibers, polyvinyl acrylonitrile fibers, polypropylene fibers, glass fibers, basalt fibers, and carbon fibers.

[0023] The length of the chopped fibers is 3 to 6 mm.

[0024] This invention also provides a method for preparing concrete made from recycled aggregate, comprising the following steps:

[0025] Quicklime, alkaline activator, silica reinforcing filler and water-reducing agent are mixed, and then water is added to mix them to obtain slurry;

[0026] After mixing the slurry and chopped fibers, modified recycled aggregate is added and mixed to obtain a mixture;

[0027] The mixture is poured and cured to obtain concrete.

[0028] Preferably, in the concrete prepared from the above-mentioned recycled aggregate, the curing temperature is 25-30°C and the curing time is 25-30 days.

[0029] The beneficial technical effects of the present invention through the above technical solution are as follows:

[0030] (1) In the concrete prepared from recycled aggregate provided in this invention, the recycled aggregate is modified by using a gel material. Specifically, hydroxyethyl acrylate, methyl methacrylate, and hydroxypropyl methacrylate undergo free radical polymerization under the action of an initiator and a crosslinking agent to form a polymer with a three-dimensional network structure. Hydroxyethyl acrylate and hydroxypropyl methacrylate contain hydroxyl functional groups, which can form hydrogen bonds or chemical bonds with the active groups on the aggregate surface, thereby enhancing the interaction between the aggregate and the polymer. methyl methacrylate contains sulfonic acid groups, which can provide good hydrophilicity and ion exchange capacity, helping to improve the dispersion and adhesion of the polymer on the aggregate surface. By forming a polymer film on the aggregate surface, the tiny pores and cracks on the aggregate surface can be filled, improving the density and strength of the aggregate. At the same time, the polymer network can enhance the bonding force between aggregate particles, improve the compressive and tensile properties of the aggregate, reduce the breakage and detachment of aggregate during concrete use, thereby improving the overall mechanical properties of the recycled aggregate. Nano-silica gel possesses a large specific surface area and high activity, enabling it to react with components such as calcium hydroxide in aggregates to generate substances like hydrated calcium silicate. These hydration products can fill the pores of the aggregates, improving their density and strength. Furthermore, nano-silica gel can react with cement hydration products during cement hydration, enhancing the interfacial adhesion between aggregates and cement paste. Through chemical reactions with aggregates and cement paste, nano-silica gel can significantly improve the strength and durability of recycled aggregates. It reduces porosity and defects in aggregates, increases their compressive and flexural strength, and strengthens the bond between aggregates and the cement matrix, thereby improving the overall mechanical properties of concrete. Specifically, acrylate monomers bond with the surface of recycled aggregates through hydrogen and ionic bonds, constructing a chemically reinforced interfacial transition zone; nano-silica precisely repairs micron-level cracks, and, in conjunction with the gel macromolecular network, achieves multi-level pore sealing.

[0031] (2) The concrete prepared by the recycled aggregate provided in this invention includes quicklime, modified recycled aggregate, alkaline activator, silica reinforcing filler, water-reducing agent, short-cut fiber and water; wherein, the high strength and good adhesion of the modified recycled aggregate, as well as the addition of short-cut fiber, effectively improve the compressive, flexural and tensile strength of concrete, enhance toughness and impact resistance, and reduce crack generation; the alkaline activator and silica reinforcing filler optimize the pore structure of concrete, reduce porosity, enhance impermeability, frost resistance and carbonation resistance, and extend service life; the silica fume modified by aminosilane coupling agent further improves the strength and stability of concrete, enabling it to maintain good performance in harsh environments. Detailed Implementation

[0032] This invention discloses a method for preparing concrete using recycled aggregates. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the same result. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0035] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0036] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0037] This invention provides a concrete prepared from recycled aggregate, comprising the following components in parts by weight:

[0038] 700-800 parts quicklime, 500-650 parts modified recycled aggregate, 150-160 parts alkaline activator, 200-220 parts silica-reinforcing filler, 7-10 parts water-reducing agent, 15-25 parts chopped fiber, and 200-250 parts water.

[0039] In this invention, the weight percentage of quicklime in the concrete prepared from the recycled aggregate is preferably 700-800 parts, more preferably 720-780 parts, and even more preferably 750-760 parts.

[0040] In this invention, the modified recycled aggregate in the concrete prepared by the recycled aggregate is preferably 500-650 parts by weight, more preferably 530-600 parts, and even more preferably 550-580 parts.

[0041] In this invention, the weight percentage of the alkaline activator in the concrete prepared from the recycled aggregate is preferably 150-160 parts, more preferably 152-157 parts, and even more preferably 155-156 parts.

[0042] In this invention, the weight percentage of silica-reinforcing filler in the concrete prepared from the recycled aggregate is preferably 205-217 parts, more preferably 210-215 parts.

[0043] In this invention, the water-reducing agent in the concrete prepared from the recycled aggregate is preferably 7 to 10 parts by weight, more preferably 7.5 to 9 parts, and even more preferably 8 to 8.5 parts.

[0044] In this invention, the weight percentage of short-cut fibers in the concrete prepared from the recycled aggregate is preferably 15 to 25 parts, more preferably 18 to 23 parts, and even more preferably 20 to 22 parts.

[0045] In this invention, the method for preparing the modified recycled aggregate includes the following steps:

[0046] Hydroxyethyl acrylate and methyl methacrylate were mixed, and their neutralization was adjusted with NaOH solution. Then, hydroxypropyl methacrylate was added and mixed to obtain a mixed monomer solution.

[0047] An initiator, nano-silica gel, N,N'-methylenebisacrylamide, and water were mixed and ultrasonically dispersed to form a uniform dispersion. The mixture was then added to the mixed monomer solution to carry out the reaction and obtain a gel material.

[0048] Recycled aggregate and gel material are mixed and cured to obtain modified recycled aggregate.

[0049] In this invention, the mass ratio of hydroxyethyl acrylate, methyl methacrylate and hydroxypropyl methacrylate is preferably 5-10:2-4:1-2, more preferably 6-9:2.5-3.5:1.2-1.8, and even more preferably 7-8:2.8-3:1.5-1.6.

[0050] In this invention, the target value for the neutralization degree is 70%.

[0051] In this invention, the mass ratio of hydroxyethyl acrylate to initiator is preferably 5-10:0.08-0.12, more preferably 6-9:0.09-0.11, and even more preferably 7-8:0.1.

[0052] In this invention, the initiator includes ammonium persulfate.

[0053] In this invention, the mass ratio of hydroxyethyl acrylate to nano-silica aerogel is preferably 5-10:4-6, more preferably 6-9:4.5-5.5, and even more preferably 7-8:4.8-5.

[0054] In this invention, the preferred ratio of hydroxyethyl acrylate, N,N'-methylenebisacrylamide, and water is 5-10 g: 0.05-0.1 g: 2.5-5 mL, more preferably 6-9 g: 0.06-0.09 g: 3-4.5 mL, and even more preferably 7-8 g: 0.07-0.08 g: 3.5-4 mL.

[0055] In this invention, the reaction is carried out by microwave polymerization, and the power of the microwave polymerization is preferably 300-400W, more preferably 320-380W, and even more preferably 330-350W; the time of the microwave polymerization is preferably 2-4h, more preferably 2.5-3.5h, and even more preferably 3h.

[0056] In this invention, the mass ratio of the recycled aggregate to the gel material is preferably 1:1 to 3, more preferably 1:1.5 to 2.5, and even more preferably 1:2.

[0057] In this invention, the curing conditions are as follows: the temperature is preferably 20-30°C, more preferably 22-28°C, and even more preferably 25°C; the time is preferably 12-24h, more preferably 15-20h, and even more preferably 17-18h; and the humidity is preferably 50-60%, more preferably 52-56%, and even more preferably 55%.

[0058] In this invention, the alkaline activator includes fly ash and sodium hydroxide.

[0059] In this invention, the mass ratio of fly ash to sodium hydroxide is preferably 8 to 10:1, more preferably 8.5 to 9.5:1, and even more preferably 9:1.

[0060] In this invention, the silica-reinforced filler comprises silica fume modified with an aminosilane coupling agent.

[0061] In this invention, the water-reducing agent includes a polycarboxylate water-reducing agent.

[0062] In this invention, the chopped fibers include at least one of polyvinyl alcohol fibers, polyvinyl acrylonitrile fibers, polypropylene fibers, glass fibers, basalt fibers, and carbon fibers.

[0063] In this invention, the length of the chopped fiber is preferably 3 to 6 mm, more preferably 3.5 to 5.5 mm, and even more preferably 4 to 5 mm.

[0064] This invention also provides a method for preparing concrete made from recycled aggregate, comprising the following steps:

[0065] Quicklime, alkaline activator, silica reinforcing filler and water-reducing agent are mixed, and then water is added to mix them to obtain slurry;

[0066] After mixing the slurry and chopped fibers, modified recycled aggregate is added and mixed to obtain a mixture;

[0067] The mixture is poured and cured to obtain concrete.

[0068] In this invention, the curing temperature is preferably 25-30°C, more preferably 26-29°C, and even more preferably 27-28°C; the curing time is preferably 25-30 days, more preferably 27-29 days, and even more preferably 28 days.

[0069] The present invention will be further described in detail below through examples. All raw materials used in the examples are commercially available.

[0070] The method for preparing the silica fume modified with the aminosilane coupling agent in the following embodiments includes the following steps:

[0071] Silica fume (SiO2≥90%) was soaked in 5% dilute hydrochloric acid (solid-liquid ratio 1:10), stirred at 60℃ for 2h, then washed with deionized water until the pH of the filtrate was neutral, and then dried at 120℃ to obtain pretreated silica fume.

[0072] γ-aminopropyltriethoxysilane (KH-550) was added dropwise to a water-ethanol mixture and magnetically stirred at 40°C for 30 h to obtain a hydrolysate.

[0073] Pretreated silica fume was added to the hydrolysate (solid-liquid ratio 1:15, the mass of γ-aminopropyltriethoxysilane in the hydrolysate was 5% of the silica fume mass), and after ultrasonic dispersion (power 300W, time 20min), it was stirred at 75℃ for 4h. After the reaction was completed, it was centrifuged and dried to obtain silica fume modified with aminosilane coupling agent.

[0074] Example 1

[0075] A type of concrete made from recycled aggregate comprises the following components in parts by weight:

[0076] 750 parts quicklime, 550 parts modified recycled aggregate, 155 parts alkaline activator, 200 parts silica fume modified with aminosilane coupling agent, 8 parts polycarboxylate superplasticizer, 20 parts chopped fiber and 200 parts water.

[0077] The method for preparing modified recycled aggregate includes the following steps:

[0078] Mix 8 parts of hydroxyethyl acrylate and 4 parts of methyl methacrylate, adjust the degree of neutralization to 70% with NaOH solution, and then add 2 parts of hydroxypropyl methacrylate to obtain a mixed monomer solution;

[0079] 0.1 parts of initiator ammonium persulfate, 6 parts of nano silica gel, N,N'-methylenebisacrylamide and water were mixed and ultrasonically vibrated to disperse them evenly. The mixture was then added to the mixed monomer solution and subjected to microwave polymerization at 350W for 3 hours to obtain a gel material. The ratio of hydroxyethyl acrylate, N,N'-methylenebisacrylamide and water was 8g:0.1g:5mL.

[0080] One part of recycled aggregate and two parts of gel material were mixed and cured at 30°C and 50% humidity for 24 hours to obtain modified recycled aggregate.

[0081] The alkaline activator consists of fly ash and sodium hydroxide in a mass ratio of 10:1;

[0082] The chopped fibers include polyvinyl alcohol fibers with a length of 6 mm;

[0083] A method for preparing concrete using recycled aggregates includes the following steps:

[0084] Quicklime, alkaline activator, silica reinforcing filler and water-reducing agent are mixed, and then water is added to mix them to obtain slurry;

[0085] After mixing the slurry and chopped fibers, modified recycled aggregate is added and mixed to obtain a mixture;

[0086] The mixture was poured and cured at 25°C for 28 days to obtain concrete.

[0087] Example 2

[0088] A type of concrete made from recycled aggregate comprises the following components in parts by weight:

[0089] 800 parts quicklime, 650 parts modified recycled aggregate, 160 parts alkaline activator, 220 parts silica fume modified with aminosilane coupling agent, 10 parts polycarboxylate superplasticizer, 25 parts chopped fiber and 200 parts water.

[0090] The method for preparing modified recycled aggregate includes the following steps:

[0091] Mix 5 parts of hydroxyethyl acrylate and 4 parts of sulfopropyl methacrylate, adjust the degree of neutralization to 70% with NaOH solution, and then add 2 parts of hydroxypropyl methacrylate to obtain a mixed monomer solution;

[0092] 0.12 parts of initiator ammonium persulfate, 4 parts of nano silica gel, N,N'-methylenebisacrylamide and water were mixed and ultrasonically vibrated to disperse them evenly. The mixture was then added to the mixed monomer solution and subjected to microwave polymerization at 400W for 4 hours to obtain a gel material. The ratio of hydroxyethyl acrylate, N,N'-methylenebisacrylamide and water was 5:0.05g:5mL.

[0093] Mix 1 part recycled aggregate with 1 to 3 parts gel material and cure at 25°C and 50% humidity for 24 hours to obtain modified recycled aggregate.

[0094] The alkaline activator consists of fly ash and sodium hydroxide in a mass ratio of 10:1;

[0095] The chopped fibers include polyvinyl alcohol fibers with a length of 6 mm;

[0096] A method for preparing concrete using recycled aggregates includes the following steps:

[0097] Quicklime, alkaline activator, silica reinforcing filler and water-reducing agent are mixed, and then water is added to mix them to obtain slurry;

[0098] After mixing the slurry and chopped fibers, modified recycled aggregate is added and mixed to obtain a mixture;

[0099] The mixture was poured and cured at 25°C for 28 days to obtain concrete.

[0100] Example 3

[0101] A type of concrete made from recycled aggregate comprises the following components in parts by weight:

[0102] 780 parts quicklime, 630 parts modified recycled aggregate, 160 parts alkaline activator, 220 parts silica fume modified with aminosilane coupling agent, 10 parts polycarboxylate superplasticizer, 15 parts chopped fiber and 250 parts water.

[0103] The method for preparing modified recycled aggregate includes the following steps:

[0104] Mix 10 parts of hydroxyethyl acrylate and 3 parts of sulfopropyl methacrylate, adjust the degree of neutralization to 70% with NaOH solution, and then add 1 part of hydroxypropyl methacrylate to obtain a mixed monomer solution.

[0105] 0.08 parts of ammonium persulfate initiator, 5 parts of nano-silica gel, N,N'-methylenebisacrylamide and water were mixed and ultrasonically vibrated to disperse them evenly. The mixture was then added to the mixed monomer solution and subjected to microwave polymerization at 400W for 3 hours to obtain a gel material. The ratio of hydroxyethyl acrylate, N,N'-methylenebisacrylamide and water was 10g:0.1g:5mL.

[0106] Mix 1 part recycled aggregate with 1 to 3 parts gel material and cure at 25°C and 50% humidity for 24 hours to obtain modified recycled aggregate.

[0107] The alkaline activator consists of fly ash and sodium hydroxide in a mass ratio of 10:1;

[0108] The chopped fibers include polyvinyl alcohol fibers with a length of 6 mm;

[0109] A method for preparing concrete using recycled aggregates includes the following steps:

[0110] Quicklime, alkaline activator, silica reinforcing filler and water-reducing agent are mixed, and then water is added to mix them to obtain slurry;

[0111] After mixing the slurry and chopped fibers, modified recycled aggregate is added and mixed to obtain a mixture;

[0112] The mixture was poured and cured at 25°C for 28 days to obtain concrete.

[0113] Example 4

[0114] A type of concrete made from recycled aggregate comprises the following components in parts by weight:

[0115] 700 parts quicklime, 500 parts modified recycled aggregate, 155 parts alkaline activator, 210 parts silica fume modified with aminosilane coupling agent, 10 parts polycarboxylate superplasticizer, 20 parts chopped fiber and 210 parts water.

[0116] The method for preparing modified recycled aggregate includes the following steps:

[0117] Mix 7 parts of hydroxyethyl acrylate and 3 parts of sulfopropyl methacrylate, adjust the degree of neutralization to 70% with NaOH solution, and then add 1 part of hydroxypropyl methacrylate to obtain a mixed monomer solution;

[0118] 0.12 parts of initiator ammonium persulfate, 6 parts of nano silica gel, N,N'-methylenebisacrylamide and water were mixed and ultrasonically vibrated to disperse them evenly. The mixture was then added to the mixed monomer solution and subjected to microwave polymerization at 300W for 3 hours to obtain a gel material. The ratio of hydroxyethyl acrylate, N,N'-methylenebisacrylamide and water was 7g:0.1g:5mL.

[0119] Mix 1 part recycled aggregate with 1 to 3 parts gel material and cure at 25°C and 50% humidity for 24 hours to obtain modified recycled aggregate.

[0120] The alkaline activator consists of fly ash and sodium hydroxide in a mass ratio of 10:1;

[0121] The chopped fibers include polyvinyl alcohol fibers with a length of 6 mm;

[0122] A method for preparing concrete using recycled aggregates includes the following steps:

[0123] Quicklime, alkaline activator, silica reinforcing filler and water-reducing agent are mixed, and then water is added to mix them to obtain slurry;

[0124] After mixing the slurry and chopped fibers, modified recycled aggregate is added and mixed to obtain a mixture;

[0125] The mixture was poured and cured at 25°C for 28 days to obtain concrete.

[0126] Comparative Example 1

[0127] A type of concrete prepared from recycled aggregate is the same as in Example 1, except that the modified recycled aggregate is replaced with untreated recycled aggregate.

[0128] Comparative Example 2

[0129] A type of concrete prepared from recycled aggregate is the same as in Example 1, except that nano-silica gel is not added in the preparation method of the modified recycled aggregate.

[0130] Comparative Example 3

[0131] A type of concrete prepared from recycled aggregate is the same as in Example 1, except that the silica fume modified with an aminosilane coupling agent is replaced with untreated silica fume.

[0132] Test Example 1

[0133] The 28-day cubic compressive strength and splitting tensile strength of concrete were tested according to the mechanical property testing methods in GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete". The test results are shown in Table 1.

[0134] Table 1

[0135] 28-day compressive strength / MPa 28-day splitting tensile strength / MPa Example 1 36.58 5.12 Example 2 34.27 4.92 Example 3 33.18 5.03 Example 4 35.30 5.08 Comparative Example 1 25.93 2.81 Comparative Example 2 29.45 3.25 Comparative Example 3 30.21 3.80

[0136] As shown in Table 1, the 28-day compressive strength and splitting tensile strength of Examples 1-4 were significantly higher than those of Comparative Example 1, indicating that the modified recycled aggregate significantly improved the mechanical properties of concrete. Comparative Example 1 used untreated recycled aggregate, and its compressive strength and splitting tensile strength were significantly lower, demonstrating that modification of recycled aggregate is crucial for improving concrete performance. Comparative Example 2, without the addition of nano-silica gel, had both compressive strength and splitting tensile strength lower than those of Example 1, indicating that nano-silica gel plays an important role in improving concrete performance. Comparative Example 3 used untreated silica fume, and its compressive strength and splitting tensile strength were both lower than those of Example 1, demonstrating that silica fume modified with aminosilane coupling agent can effectively improve the mechanical properties of concrete.

[0137] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A type of concrete prepared from recycled aggregate, characterized in that, Includes the following components in parts by weight: 700-800 parts quicklime, 500-650 parts modified recycled aggregate, 150-160 parts alkaline activator, 200-220 parts silica-reinforcing filler, 7-10 parts water-reducing agent, 15-25 parts chopped fiber and 200-250 parts water; The method for preparing the modified recycled aggregate includes the following steps: mixing hydroxyethyl acrylate and methyl methacrylate, adjusting the degree of neutralization with NaOH solution, and then adding hydroxypropyl methacrylate to obtain a mixed monomer solution; An initiator, nano-silica gel, N,N'-methylenebisacrylamide, and water were mixed, dispersed, and then added to the mixed monomer solution to carry out the reaction, thereby obtaining a gel material. Recycled aggregate and gel material are mixed and cured to obtain modified recycled aggregate; The mass ratio of hydroxyethyl acrylate, propyl methacrylate sulfonate and hydroxypropyl methacrylate is 5-10:2-4:1-2; The mass ratio of hydroxyethyl acrylate to initiator is 5–10:0.08–0.12; The mass ratio of hydroxyethyl acrylate to nano-silica aerogel is 5-10:4-6; The ratio of hydroxyethyl acrylate, N,N'-methylenebisacrylamide, and water is 5-10 g: 0.05-0.1 g: 2.5-5 mL; The reaction is carried out by microwave polymerization, the power of which is 300-400W and the time is 2-4 hours. The mass ratio of the recycled aggregate to the gel material is 1:1 to 3; The curing conditions are: temperature 20-30°C, time 12-24 hours, and humidity 50-60%.

2. The concrete prepared from recycled aggregate according to claim 1, characterized in that, The alkaline activator includes fly ash and sodium hydroxide; The mass ratio of fly ash to sodium hydroxide is 8-10:

1.

3. The concrete prepared from recycled aggregate according to claim 1, characterized in that, The silica-reinforced filler comprises silica fume modified with an aminosilane coupling agent.

4. The concrete prepared from recycled aggregate according to claim 1, characterized in that, The water-reducing agent includes polycarboxylate water-reducing agents.

5. The concrete prepared from recycled aggregate according to claim 1, characterized in that, The chopped fibers include at least one of polyvinyl alcohol fibers, polyvinyl acrylonitrile fibers, polypropylene fibers, glass fibers, basalt fibers, and carbon fibers.

6. The concrete prepared from recycled aggregate according to claim 1, characterized in that, The length of the chopped fibers is 3 to 6 mm.

7. A method for preparing concrete made from recycled aggregate according to any one of claims 1 to 6, characterized in that, Includes the following steps: Quicklime, alkaline activator, silica reinforcing filler and water-reducing agent are mixed, and then water is added to mix them to obtain slurry; After mixing the slurry and chopped fibers, modified recycled aggregate is added and mixed to obtain a mixture; The mixture is poured and cured to obtain concrete.

8. The method for preparing concrete from recycled aggregate according to claim 7, characterized in that, The curing temperature is 25–30°C, and the curing time is 25–30 days.