Low-viscosity self-compacting concrete and preparation method thereof

Abstract

The invention discloses low-viscosity self-compacting concrete and a preparation method thereof, and relates to the technical field of concrete materials, the low-viscosity self-compacting concrete comprises the following raw materials by weight: 330-370 parts of cement, 202-222 parts of fly ash, 40-50 parts of silica fume, 800-900 parts of fine aggregate, 900-100 parts of coarse aggregate, 172-192 parts of water, 9-15 parts of a water reducer, and 0.2-0.3 part of a viscosity modifier; the viscosity modifier is prepared from the following raw materials in parts by weight: 4 to 10 parts of acrylic acid, 1 to 12 parts of hydroxyethyl acrylate, 0.06 to 2 parts of a reducing agent, 0.9 to 2.5 parts of an oxidizing agent and 0.8 to 1.6 parts of a chain transfer agent. The viscosity modifier is added while the mixing amount of the fly ash is increased, so that the viscosity can be controlled while the cost for preparing the self-compacting concrete is reduced, the self-compacting concrete has excellent working performance, and the purposes of reducing the cost and improving the efficiency are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of concrete materials, and in particular to a low-viscosity self-compacting concrete and a preparation method thereof. Background Art

[0002] With the rapid development of the modern civil engineering industry, the demand for concrete is increasing. However, traditional concrete materials are difficult to meet the needs of development due to their limited performance. Self-compacting concrete is a type of concrete that can be filled and compacted by its own gravity flow without the help of vibration. It can greatly simplify the pouring process and save manpower. Since self-compacting concrete is designed based on a high amount of cementitious materials, compared with ordinary concrete, it uses more materials and has a higher cost. Its viscosity will also increase due to the large amount of cementitious materials used.

[0003] At present, the concrete market is highly competitive and urgently needs to reduce costs and increase efficiency, while ensuring that concrete has qualified performance. Self-compacting concrete is a special concrete with high cost and high demand. If its economy can be improved and its performance can be guaranteed, it will produce huge benefits.

[0004] Patent CN106365536B discloses a self-compacting expansive concrete, which includes the following ingredients, by weight: 340-400 parts of cement, 80-120 parts of mineral powder, 50-70 parts of fly ash, 900-1100 parts of coarse aggregate, 680-760 parts of fine aggregate, 10-20 parts of water reducer, 23-29 parts of expansive agent, 3.0-3.4 parts of synergist, 2.4-2.8 parts of sodium monofluorophosphate, 2.8-3.4 parts of sodium alginate, and 350-390 parts of water.

[0005] Patent CN107098642B discloses a high-strength self-compacting concrete, whose raw materials include 355-367 parts of cement, 724-748 parts of sand, 885-915 parts of 5-16 mm crushed stone, 77-87 parts of fly ash, 103-119 parts of mineral powder, 26-32 parts of silica fume, 12.40-14.42 parts of special admixture, 4-5 parts of shrinkage reducer, and 157-171 parts of water, by weight.

[0006] The current self-compacting concrete, as disclosed in the above patents, uses a relatively large proportion of cement, which is expensive, resulting in a high cost of the self-compacting concrete. Summary of the invention

[0007] In view of the problem of high production cost of existing self-compacting concrete, the purpose of the present invention is to provide a low-viscosity self-compacting concrete and a preparation method thereof. By increasing the fly ash dosage and adding a viscosity regulator, the cost of preparing the self-compacting concrete is reduced while the viscosity can be controlled, and the concrete has excellent working performance, thereby achieving the purpose of reducing costs and increasing efficiency.

[0008] The present invention is achieved through the following technical solutions:

[0009] In a first aspect, the present application provides a low-viscosity self-compacting concrete, which is composed of the following raw materials in parts by weight: 330 to 370 parts of cement, 202 to 222 parts of fly ash, 40 to 50 parts of silica fume, 800 to 900 parts of fine aggregate, 900 to 100 parts of coarse aggregate, 172 to 192 parts of water, 9 to 15 parts of water reducer, and 0.2 to 0.3 parts of viscosity regulator;

[0010] The viscosity modifier is composed of the following raw materials in parts by weight: 4 to 10 parts of acrylic acid, 1 to 12 parts of hydroxyethyl acrylate, 0.06 to 2 parts of a reducing agent, 0.9 to 2.5 parts of an oxidizing agent, and 0.8 to 1.6 parts of a chain transfer agent.

[0011] The cement is ordinary silicate cement or composite silicate cement 42.5 or 52.5 or a mixture of several thereof.

[0012] The low-strength self-compacting concrete of the present invention reduces the amount of expensive cement by increasing the amount of fly ash added, thereby achieving the effect of reducing the production cost of the self-compacting concrete. At the same time, the unique molecular structure of the added viscosity regulator produces steric hindrance and electrostatic repulsion between the cement molecules, preventing the cement molecules from approaching each other, thereby achieving the effect of reducing viscosity. Moreover, the reactive monomer of the viscosity regulator has good solubility, making it more compatible with the water reducing agent, thereby enabling the prepared self-compacting concrete to have excellent working performance and maintain economy under the condition of good strength performance.

[0013] The fly ash in the present invention is composed of a large number of spherical glass bodies with smooth surfaces, which plays a role of "ball lubrication", can break the flocculation structure of cement slurry, and can improve the cohesiveness of concrete. At the same time, the morphology and hydrophilicity of fly ash particles, and its spherical glass bodies can absorb a layer of water film, which can make the concrete have good water retention. In addition, silica ash particles are fine and highly dispersible. The main component of silica ash is active silicon dioxide. Silica ash can effectively improve the strength of concrete through filling effect and volcanic effect, and can also play a unique micro-aggregate effect, improve the particle size distribution of particles, make the particle raw materials pile up more tightly, and through the mutual cooperation between the raw materials, the prepared self-compacting concrete has good performance and low cost.

[0014] Furthermore, the reducing agent includes one of ethyl methyl cellulose ether and hydroxypropyl methyl cellulose ether.

[0015] Furthermore, the oxidant includes one of hydrogen peroxide and benzoyl peroxide.

[0016] Furthermore, the chain transfer agent includes one of thioglycolic acid, mercaptopropionic acid, and mercaptoethanol.

[0017] Furthermore, the silica fume activity index is greater than 110%.

[0018] Furthermore, the fine aggregate is medium sand with a fineness modulus of 2.6 to 2.8.

[0019] Furthermore, the coarse aggregate is crushed stone with a size of 5 mm to 20 mm.

[0020] Furthermore, the fly ash includes one of Class I fly ash and Class II fly ash.

[0021] Furthermore, the preparation method of the viscosity modifier comprises the following steps:

[0022] Put the reducing agent and deionized water in a reaction container and stir to fully dissolve them;

[0023] Then, acrylic acid, hydroxyethyl acrylate, oxidant and chain transfer agent are added dropwise into the container, reacted at an ambient temperature of 25°C to 35°C, and kept warm for 1h to 1.2h. After the reaction is completed, the pH value is adjusted to 6 to 7 to prepare a viscosity regulator.

[0024] In a second aspect, the present application provides a method for preparing a low-viscosity self-compacting concrete, comprising the following steps:

[0025] Add fine aggregate, coarse aggregate and part of water into a mixer and mix well;

[0026] Add cement, fly ash, silica fume, high-performance water reducing agent and viscosity regulator and stir to mix;

[0027] Add the remaining water and stir to mix well to obtain a self-compacting concrete with high fly ash content and low viscosity.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] The low-strength self-compacting concrete of the present invention reduces the amount of expensive cement by increasing the amount of fly ash added, thereby achieving the effect of reducing the production cost of the self-compacting concrete. At the same time, the added viscosity regulator reduces the viscosity of the self-compacting concrete, and can still maintain excellent working performance under high gel material dosage. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0031] Figure 1 The figure is a graph showing the compressive strength test results of concrete prepared by the methods of the embodiment and the comparative example. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0033] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range.

[0034] If not otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0035] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0036] If there is no special explanation, all the steps of the present application can be performed sequentially or randomly, preferably sequentially.

[0037] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0038] Example 1

[0039] This embodiment provides a method for preparing low-viscosity self-compacting concrete, which is composed of the following raw materials in parts by weight: 350 parts of cement, 212 parts of fly ash, 45 parts of silica fume, 850 parts of fine aggregate, 950 parts of coarse aggregate, 182 parts of water, 12 parts of polycarboxylate water reducer, and 0.25 parts of viscosity regulator;

[0040] The viscosity modifier is composed of the following raw materials in parts by weight: 10 parts of acrylic acid, 1 part of hydroxyethyl acrylate, 0.06 parts of ethyl methyl cellulose ether, 0.9 parts of hydrogen peroxide, and 1.6 parts of thioglycolic acid.

[0041] The fine aggregate is medium sand with a fineness modulus of 2.7, and the coarse aggregate is crushed stone of 5-20 mm.

[0042] The preparation method is:

[0043] S1. Place ethyl methyl cellulose ether and deionized water in a reaction vessel and stir to fully dissolve them;

[0044] S2, then dripping acrylic acid, hydroxyethyl acrylate, hydrogen peroxide and thioglycolic acid into the container for 1.5 hours, reacting at an ambient temperature of 25° C. to 35° C., keeping warm for 1 hour, and adjusting the pH value to 6 after the reaction is completed to prepare a viscosity regulator;

[0045] S3. Add fine aggregate, coarse aggregate and half of the water into a mixer and premix for 2 minutes;

[0046] S4, adding cement, fly ash, silica fume, polycarboxylate water reducer and the viscosity regulator prepared in step S2 and stirring for 2 minutes;

[0047] S5. Add the remaining water and stir to mix well to obtain a self-compacting concrete with high fly ash content and low viscosity.

[0048] Example 2

[0049] This embodiment provides a method for preparing low-viscosity self-compacting concrete. Different from Embodiment 1, the amount of each raw material used in the concrete in this embodiment is different, and the concrete is composed of the following raw materials in parts by weight: 360 parts of cement, 222 parts of fly ash, 50 parts of silica fume, 850 parts of fine aggregate, 950 parts of coarse aggregate, 190 parts of water, 12 parts of polycarboxylate water reducer, and 0.25 parts of viscosity regulator;

[0050] The viscosity modifier is composed of the following raw materials in parts by weight: 10 parts of acrylic acid, 1 part of hydroxyethyl acrylate, 0.06 parts of ethyl methyl cellulose ether, 0.9 parts of hydrogen peroxide, and 1.6 parts of thioglycolic acid.

[0051] The fine aggregate is medium sand with a fineness modulus of 2.7, and the coarse aggregate is crushed stone of 5-20 mm.

[0052] The preparation method is:

[0053] S1. Place ethyl methyl cellulose ether and deionized water in a reaction vessel and stir to fully dissolve them;

[0054] S2, then dripping acrylic acid, hydroxyethyl acrylate, hydrogen peroxide and thioglycolic acid into the container for 1.5 hours, reacting at an ambient temperature of 25° C. to 35° C., keeping warm for 1 hour, and adjusting the pH value to 6 after the reaction is completed to prepare a viscosity regulator;

[0055] S3. Add fine aggregate, coarse aggregate and half of the water into a mixer and premix for 2 minutes;

[0056] S4, adding cement, fly ash, silica fume, polycarboxylate water reducer and the viscosity regulator prepared in step S2 and stirring for 2 minutes;

[0057] S5. Add the remaining water and stir to mix well to obtain a self-compacting concrete with high fly ash content and low viscosity.

[0058] Example 3

[0059] This embodiment provides a method for preparing low-viscosity self-compacting concrete. Different from Embodiment 1, the amount of each raw material used in the concrete in this embodiment is different, and the concrete is composed of the following raw materials in parts by weight: 340 parts of cement, 207 parts of fly ash, 45 parts of silica fume, 800 parts of fine aggregate, 950 parts of coarse aggregate, 177 parts of water, 12 parts of polycarboxylate water reducer, and 0.25 parts of viscosity regulator;

[0060] The viscosity modifier is composed of the following raw materials in parts by weight: 10 parts of acrylic acid, 1 part of hydroxyethyl acrylate, 0.06 parts of ethyl methyl cellulose ether, 0.9 parts of hydrogen peroxide, and 1.6 parts of thioglycolic acid.

[0061] The fine aggregate is medium sand with a fineness modulus of 2.7, and the coarse aggregate is crushed stone of 5-20 mm.

[0062] The preparation method is:

[0063] S1. Place ethyl methyl cellulose ether and deionized water in a reaction vessel and stir to fully dissolve them;

[0064] S2, then dripping acrylic acid, hydroxyethyl acrylate, hydrogen peroxide and thioglycolic acid into the container for 1.5 hours, reacting at an ambient temperature of 25° C. to 35° C., keeping warm for 1 hour, and adjusting the pH value to 6 after the reaction is completed to prepare a viscosity regulator;

[0065] S3. Add fine aggregate, coarse aggregate and half of the water into a mixer and premix for 2 minutes;

[0066] S4, adding cement, fly ash, silica fume, polycarboxylate water reducer and the viscosity regulator prepared in step S2 and stirring for 2 minutes;

[0067] S5. Add the remaining water and stir to mix well to obtain a self-compacting concrete with high fly ash content and low viscosity.

[0068] Example 4

[0069] This embodiment provides a method for preparing low-viscosity self-compacting concrete. The difference from Embodiment 1 is that the amounts of various raw materials of the viscosity modifier in this embodiment are different, and the concrete is composed of the following raw materials in parts by weight: 350 parts of cement, 212 parts of fly ash, 45 parts of silica fume, 850 parts of fine aggregate, 950 parts of coarse aggregate, 182 parts of water, 12 parts of polycarboxylate water reducer, and 0.25 parts of viscosity modifier.

[0070] The viscosity modifier is composed of the following raw materials in parts by weight: 4 parts of acrylic acid, 12 parts of hydroxyethyl acrylate, 2 parts of ethyl methyl cellulose ether, 2.5 parts of hydrogen peroxide, and 0.8 parts of thioglycolic acid.

[0071] The fine aggregate is medium sand with a fineness modulus of 2.7, and the coarse aggregate is crushed stone of 5-20 mm.

[0072] The preparation method is:

[0073] S1. Place ethyl methyl cellulose ether and deionized water in a reaction vessel and stir to fully dissolve them;

[0074] S2, then dripping acrylic acid, hydroxyethyl acrylate, hydrogen peroxide and thioglycolic acid into the container for 1.5 hours, reacting at an ambient temperature of 25° C. to 35° C., keeping warm for 1 hour, and adjusting the pH value to 6 after the reaction is completed to prepare a viscosity regulator;

[0075] S3. Add fine aggregate, coarse aggregate and half of the water into a mixer and premix for 2 minutes;

[0076] S4, adding cement, fly ash, silica fume, polycarboxylate water reducer and the viscosity regulator prepared in step S2 and stirring for 2 minutes;

[0077] S5. Add the remaining water and stir to mix well to obtain a self-compacting concrete with high fly ash content and low viscosity.

[0078] Example 5

[0079] This embodiment provides a method for preparing low-viscosity self-compacting concrete. The difference from Embodiment 1 is that the amounts of various raw materials of the viscosity modifier in this embodiment are different, and the concrete is composed of the following raw materials in parts by weight: 350 parts of cement, 212 parts of fly ash, 45 parts of silica fume, 850 parts of fine aggregate, 950 parts of coarse aggregate, 182 parts of water, 12 parts of polycarboxylate water reducer, and 0.25 parts of viscosity modifier.

[0080] The viscosity modifier is composed of the following raw materials in parts by weight: 7 parts of acrylic acid, 8 parts of hydroxyethyl acrylate, 1 part of ethyl methyl cellulose ether, 1.5 parts of hydrogen peroxide, and 1.2 parts of thioglycolic acid.

[0081] The fine aggregate is medium sand with a fineness modulus of 2.7, and the coarse aggregate is crushed stone of 5-20 mm.

[0082] The preparation method is:

[0083] S1. Place ethyl methyl cellulose ether and deionized water in a reaction vessel and stir to fully dissolve them;

[0084] S2, then dripping acrylic acid, hydroxyethyl acrylate, hydrogen peroxide and thioglycolic acid into the container for 1.5 hours, reacting at an ambient temperature of 25° C. to 35° C., keeping warm for 1 hour, and adjusting the pH value to 6 after the reaction is completed to prepare a viscosity regulator;

[0085] S3. Add fine aggregate, coarse aggregate and half of the water into a mixer and premix for 2 minutes;

[0086] S4, adding cement, fly ash, silica fume, polycarboxylate water reducer and the viscosity regulator prepared in step S2 and stirring for 2 minutes;

[0087] S5. Add the remaining water and stir to mix well to obtain a self-compacting concrete with high fly ash content and low viscosity.

[0088] Comparative Example 1

[0089] This comparative example provides a method for preparing self-compacting concrete. Different from Example 1, the amount of each raw material used in the concrete in this comparative example is different, and the concrete is composed of the following raw materials in parts by weight: 441 parts of cement, 121 parts of fly ash, 45 parts of silica fume, 850 parts of fine aggregate, 950 parts of coarse aggregate, 182 parts of water, 12 parts of polycarboxylate water reducer, and 0.25 parts of viscosity regulator;

[0090] The viscosity modifier is composed of the following raw materials in parts by weight: 10 parts of acrylic acid, 1 part of hydroxyethyl acrylate, 0.06 parts of ethyl methyl cellulose ether, 0.9 parts of hydrogen peroxide, and 1.6 parts of thioglycolic acid.

[0091] The fine aggregate is medium sand with a fineness modulus of 2.7, and the coarse aggregate is crushed stone of 5-20 mm.

[0092] The preparation method is:

[0093] S1. Place ethyl methyl cellulose ether and deionized water in a reaction vessel and stir to fully dissolve them;

[0094] S2, then dripping acrylic acid, hydroxyethyl acrylate, hydrogen peroxide and thioglycolic acid into the container for 1.5 hours, reacting at an ambient temperature of 25° C. to 35° C., keeping warm for 1 hour, and adjusting the pH value to 6 after the reaction is completed to prepare a viscosity regulator;

[0095] S3. Add fine aggregate, coarse aggregate and half of the water into a mixer and premix for 2 minutes;

[0096] S4, adding cement, fly ash, silica fume, polycarboxylate water reducer and the viscosity regulator prepared in step S2 and stirring for 2 minutes;

[0097] S5. Add the remaining water and stir to mix well to obtain self-compacting concrete.

[0098] Comparative Example 2

[0099] This comparative example provides a method for preparing a self-compacting concrete. Unlike Example 1, no viscosity regulator is added in this comparative example, and the concrete is composed of the following raw materials in parts by weight: 350 parts of cement, 212 parts of fly ash, 45 parts of silica fume, 850 parts of fine aggregate, 950 parts of coarse aggregate, 182 parts of water, and 12 parts of polycarboxylate water reducer.

[0100] The preparation method is:

[0101] S1. Add fine aggregate, coarse aggregate and half of the water into a mixer and premix for 2 minutes;

[0102] S2, add cement, fly ash, silica fume and polycarboxylate water reducer and stir for 2 minutes;

[0103] S3. Add the remaining water and stir to mix well to obtain self-compacting concrete.

[0104] Comparative Example 3

[0105] The comparative example provides a method for preparing a self-compacting concrete. Unlike comparative example 1, no viscosity regulator is added in the comparative example, and the concrete is composed of the following raw materials in parts by weight: 441 parts of cement, 121 parts of fly ash, 45 parts of silica fume, 850 parts of fine aggregate, 950 parts of coarse aggregate, 182 parts of water, and 12 parts of polycarboxylic acid water reducer.

[0106] The preparation method is:

[0107] S1. Add fine aggregate, coarse aggregate and half of the water into a mixer and premix for 2 minutes;

[0108] S2, add cement, fly ash, silica fume and polycarboxylate water reducer and stir for 2 minutes;

[0109] S3. Add the remaining water and stir to mix well to obtain self-compacting concrete.

[0110] Comparative Example 4

[0111] The comparative example provides a method for preparing self-compacting concrete, which is different from Example 1 in that 0.25 parts of a conventional viscosity regulator are added in the comparative example. The comparative example is composed of the following raw materials in parts by weight: 350 parts of cement, 212 parts of fly ash, 45 parts of silica fume, 850 parts of fine aggregate, 950 parts of coarse aggregate, 182 parts of water, 12 parts of polycarboxylate water reducer, and 0.25 parts of concrete viscosity regulator TZ-2L provided by a Nanjing trading company.

[0112] The preparation method is:

[0113] S1. Add fine aggregate, coarse aggregate and half of the water into a mixer and premix for 2 minutes;

[0114] S2, add cement, fly ash, silica fume, polycarboxylate water reducer, and traditional viscosity regulator and stir for 2 minutes;

[0115] S3. Add the remaining water and stir to mix well to obtain self-compacting concrete.

[0116] The properties of the self-compacting concrete prepared by the methods of Examples 1 to 5 and Comparative Examples 1 to 4 were tested. The test results are as follows: Figure 1 As shown in Table 1. Among them, the concrete compressive strength test was carried out in accordance with GBT 50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete", and the specimen size was 100mm×100mm×100mm. The expansion degree, expansion time and inversion time tests were carried out in accordance with JGJT 283-2012 "Technical Specifications for Application of Self-compacting Concrete".

[0117] Table 1 Test results of expansion degree, expansion time and rewinding time of each sample

[0118]

[0119] from Figure 1 It can be seen from the test data that there is no obvious difference in compressive strength between the embodiments and the comparative examples, indicating that the modifications made in the present application have no significant impact on the strength of the self-compacting concrete.

[0120] It can be seen from the data in Table 1 that, compared with the comparative examples, the expansion degree, expansion time and drum inversion time of all embodiments are greatly improved. From the data comparison between Example 1 and Comparative Example 1, it can be found that the increase in the fly ash content can greatly increase the expansion degree of concrete. From the comparison between Example 1 and Comparative Example 2, it can be found that the viscosity regulator can greatly reduce the viscosity of concrete and reduce the expansion and drum inversion time. From the comparison between Example 1 and Comparative Example 3, it can be found that the use of the viscosity regulator while increasing the fly ash content can greatly increase the expansion degree of concrete and reduce the viscosity of concrete, and reduce the expansion and drum inversion time. From the comparative example of Example 1 and Comparative Example 4, it can be found that the viscosity regulator of the present invention has obvious improvements on the performance of the concrete expansion degree, expansion time and drum inversion time.

[0121] Field application cases

[0122] In a design industrial park in Sichuan, the foundation needs to be cast with self-compacting concrete, and the construction period is tight. The self-compacting concrete is prepared by the preparation method of Example 1, which greatly reduces the expansion time and the inverting time of the concrete, and finally the casting is completed before the construction period.

[0123] In summary, the low-viscosity self-compacting concrete prepared by the method of the present application has good mechanical properties and excellent working performance, and the cost is lower than that of ordinary self-compacting concrete.

[0124] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low-viscosity self-compacting concrete, characterized in that: The invention is composed of the following raw materials in parts by weight: 330 to 370 parts of cement, 202 to 222 parts of fly ash, 40 to 50 parts of silica fume, 800 to 900 parts of fine aggregate, 900 to 100 parts of coarse aggregate, 172 to 192 parts of water, 9 to 15 parts of water reducing agent, and 0.2 to 0.3 parts of viscosity regulator; The viscosity modifier is composed of the following raw materials in parts by weight: 4 to 10 parts of acrylic acid, 1 to 12 parts of hydroxyethyl acrylate, 0.06 to 2 parts of a reducing agent, 0.9 to 2.5 parts of an oxidizing agent, and 0.8 to 1.6 parts of a chain transfer agent.

2. A low-viscosity self-compacting concrete according to claim 1, characterized in that: The reducing agent includes one of ethyl methyl cellulose ether and hydroxypropyl methyl cellulose ether.

3. A low-viscosity self-compacting concrete according to claim 1, characterized in that: The oxidant includes one of hydrogen peroxide and benzoyl peroxide.

4. A low-viscosity self-compacting concrete according to claim 1, characterized in that: The chain transfer agent includes one of thioglycolic acid, mercaptopropionic acid and mercaptoethanol.

5. The low-viscosity self-compacting concrete according to claim 1, characterized in that: The silica fume activity index is greater than 110%.

6. The low-viscosity self-compacting concrete according to claim 1, characterized in that: The fine aggregate is medium sand with a fineness modulus of 2.6 to 2.

8.

7. The low-viscosity self-compacting concrete according to claim 1, characterized in that: The coarse aggregate is crushed stone with a size of 5 mm to 20 mm.

8. The low-viscosity self-compacting concrete according to claim 1, characterized in that: The fly ash includes one of Class I fly ash and Class II fly ash.

9. The low-viscosity self-compacting concrete according to claim 1, characterized in that: The preparation method of the viscosity modifier comprises the following steps: Put the reducing agent and deionized water in a reaction container and stir to fully dissolve them; Then, acrylic acid, hydroxyethyl acrylate, oxidant and chain transfer agent are added dropwise into the container, reacted at an ambient temperature of 25°C to 35°C, and kept warm for 1h to 1.2h. After the reaction is completed, the pH value is adjusted to 6 to 7 to prepare a viscosity regulator.

10. A method for preparing low-viscosity self-compacting concrete, characterized in that: The following steps are involved: Add fine aggregate, coarse aggregate and part of water into a mixer and mix well; Add cement, fly ash, silica fume, high-performance water reducing agent and viscosity regulator and stir to mix; Add the remaining water and stir to mix well to obtain a self-compacting concrete with high fly ash content and low viscosity.

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