Self-compacting concrete based on modified water granulated slag as well as preparation method and application of self-compacting concrete

Abstract

The invention provides self-compacting concrete based on modified water granulated slag and a preparation method and application thereof.The preparation method comprises the following steps that S1, the water granulated slag is screened through a 14-24-mesh sieve, screen residue water granulated slag with the particle size being 0.71-1.4 mm is obtained and mixed with an exciting agent, water is added for stirring, curing is conducted for 6-8 d, and the modified water granulated slag is obtained for standby application; s2, adding inorganic salt into the water reducing agent prepared in S2 to obtain an early-strength water reducing agent for later use; and S3, weighing cement, fly ash, machine-made sand and the modified water granulated slag prepared in the S1 according to the required proportion, uniformly mixing, adding an early strength water reducing agent and water, mixing again, adding stones, and stirring for 2-5 minutes to obtain the self-compacting concrete based on the modified water granulated slag. The modified water granulated slag is introduced to replace mineral powder and part of machine-made sand, the early strength water reducing agent is matched, the concrete raw material ratio is optimized, the fluidity, working performance and strength of the self-compacting concrete are improved, the obtained self-compacting concrete based on the modified water granulated slag is free of segregation, bleeding, laitance and sinking phenomena, and excellent durability and service life are ensured.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, and in particular to a self-compacting concrete based on modified water slag, and a preparation method and application thereof. Background Art

[0002] Self-compacting concrete (SCC) refers to concrete that can flow and compact under its own gravity, can completely fill the formwork even in the presence of dense steel bars, and has good homogeneity and does not require additional vibration. In the field of concrete technology, self-compacting concrete has been widely used due to its good filling, self-compacting and high construction efficiency, and is known as "the most revolutionary development in concrete construction technology in recent decades." The mix design of self-compacting concrete needs to fully consider the relationship and contradiction between the fluidity, anti-segregation, self-filling, slurry dosage and volume stability of self-compacting concrete. Traditional self-compacting concrete is usually prepared from raw materials such as cement, fly ash, mineral powder, sand, gravel, water reducer and water. However, these traditional formulas still have certain limitations in some aspects, especially in terms of fluidity, workability and strength development.

[0003] Specifically, in the traditional self-compacting concrete formula, in order to improve the fluidity and encapsulation of self-compacting concrete, the amount of cementitious materials used in self-compacting concrete is generally not less than 400kg / m 3 This part of the cementitious material generally contains 50-100 kg / m 3 The mineral powder with high specific surface area will increase the water consumption of concrete and reduce the fluidity of concrete, which will reduce the anti-segregation property of self-compacting concrete and lead to segregation and stratification. In addition, the sand ratio in traditional self-compacting concrete formula is generally more than 45%, and a higher sand ratio will also reduce the fluidity of concrete and affect the strength of concrete.

[0004] Chinese patent CN116496040A "Self-compacting concrete and its preparation method" discloses a self-compacting concrete with machine-made sand, which improves the fluidity and workability of concrete by using slag and fly ash, and improves the workability of concrete by using carboxymethyl cellulose, thereby increasing the strength of self-compacting concrete. However, the amount of cement, fly ash and other cementitious materials used is too large, which reduces the segregation resistance of self-compacting concrete, and segregation and stratification are prone to occur, and the strength still needs to be further improved.

[0005] Therefore, it is of great significance to provide a self-compacting concrete based on modified water slag, which can reduce the segregation and stratification of concrete, improve the fluidity of concrete, and have excellent strength, as well as a preparation method and application thereof. Summary of the invention

[0006] In view of the fact that the existing self-compacting concrete has an excessive amount of cementitious materials, which reduces the segregation resistance of the self-compacting concrete, makes it easy to segregate and delaminate, and the strength still needs to be further improved, the present invention provides a self-compacting concrete based on modified slag, and a preparation method and application thereof. By introducing modified slag to replace mineral powder and part of machine-made sand, and combining with an early strength water reducer, the ratio of concrete raw materials is optimized, thereby improving the fluidity, workability and strength of the self-compacting concrete. The obtained self-compacting concrete based on modified slag has excellent fluidity, high strength, low-cost production advantages, outstanding environmental protection characteristics, excellent impermeability and high density, and is completely free of segregation, bleeding, slurry and sinking phenomena, and the aggregate is evenly distributed, ensuring excellent durability and service life, and can meet higher requirements for engineering applications. It has low cost, a wide source, good environmental and economic benefits, is suitable for large-scale promotion and industrialized production, and has positive significance for promoting the sustainable development of the construction industry.

[0007] To achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing self-compacting concrete based on modified slag comprises the following steps:

[0009] S1. The water residue was sieved through a 14-24 mesh sieve to obtain a particle size of 0.71-1.4mm of the sieve residue, mixed with an activator, stirred with water, and cured for 6-8d to obtain the modified water residue for standby use;

[0010] S2. Add inorganic salt to the water reducing agent to obtain an early strength water reducing agent for standby use;

[0011] S3. Cement, fly ash, machine-made sand and the modified water slag prepared in S1 are weighed according to the required proportion, mixed evenly, the early strength water reducer prepared in S2 and water are added, mixed again, gravel is added, and stirred for 2-5 minutes to obtain the self-compacting concrete based on the modified water slag.

[0012] Furthermore, the activator in S1 is calcium hydroxide and / or calcium oxide.

[0013] Furthermore, the mass ratio of the screened water residue and the activator in S1 is 1:(0.0005-0.003).

[0014] Furthermore, the specific surface area of ​​the decoration waste powder is greater than 450m 2 / kg.

[0015] Furthermore, the sieves in S1 are 16 mesh and 18 mesh, and the particle size of the residual water slag is 1.0-1.18 mm.

[0016] Furthermore, the water reducer in S2 is a polycarboxylic acid-based water reducer; and the inorganic salt in S2 is sodium sulfate and / or potassium sulfate.

[0017] Furthermore, the mass ratio of the water reducing agent and the inorganic salt in S2 is 1:(0.01-0.03).

[0018] Another object of the present invention is to provide a self-compacting concrete based on modified slag.

[0019] A self-compacting concrete based on modified slag is prepared according to any of the above-mentioned methods for preparing self-compacting concrete based on modified slag.

[0020] Furthermore, the following components are included, calculated by weight: 250-350 parts by weight of cement, 80-120 parts by weight of fly ash, 150-300 parts by weight of modified slag, 550-700 parts by weight of machine-made sand, 850-950 parts by weight of gravel, 155-180 parts by weight of water, and 7-15 parts by weight of early strength water reducing agent.

[0021] Another object of the present invention is to provide an application of self-compacting concrete based on modified slag.

[0022] A self-compacting concrete based on modified slag is used for preparing concrete.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] The self-compacting concrete based on modified slag provided by the present invention adopts modified slag to replace mineral powder and part of machine-made sand. By screening the slag, the slag particles are ensured to match the particle grading of the self-compacting concrete, and its fluidity and filling density are improved. At the same time, the slag particles larger than conventional mineral powder particles are continuously hydrated in the concrete system, so that the strength growth period is extended to more than 56 days, and the concrete has excellent strength. The slag surface is treated with an activator, and an early strength reducing agent with an inorganic salt early strength agent is added. After the inorganic salt is dissolved in water, the corresponding ions, such as Na + , K + 、SO4 2-These ions can react with the mineral components in cement clinker and slag, accelerate their hydration process, and improve the early strength of concrete; at the same time, the addition of inorganic salts will also change the charge distribution and adsorption layer structure on the surface of cement particles and slag particles, thereby affecting their dispersion and agglomeration behavior in water, which helps cement and slag particles to contact water more fully, accelerate the hydration reaction, and promote the hydration reaction of modified slag, improve its utilization rate and performance contribution, and make modified slag more prone to hydration after contacting water, which can further improve the early strength of self-compacting concrete based on modified slag, significantly improve the compactness and impermeability of self-compacting concrete based on modified slag, enhance its strength and durability, and effectively extend its service life. Among them, in addition, modified slag comes from the reuse of industrial waste, which can not only reduce production costs and carbon emissions, but also improve the fluidity of concrete, reduce the segregation and stratification of concrete, and ensure the uniformity and consistency of concrete.

[0025] The self-compacting concrete based on modified water slag provided by the present invention has excellent fluidity, high strength, low-cost production advantages, outstanding environmental protection characteristics, excellent anti-seepage performance and high density, and is completely free of segregation, bleeding, slurry and sinking phenomena. The aggregate is evenly distributed, ensuring excellent durability and service life, and can meet higher requirements of engineering applications. It has low cost, wide sources, good environmental and economic benefits, is suitable for large-scale promotion and industrialized production, and has positive significance for promoting the sustainable development of the construction industry. DETAILED DESCRIPTION

[0026] In order to better illustrate the purpose, technical scheme and advantages of the present invention, the present invention is further described by the following examples. Obviously, the following examples are only part of the embodiments of the present invention, rather than all the embodiments; it should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, rather than to limit the scope of protection of the present invention.

[0027] The raw materials in the examples can all be obtained commercially; unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0028] Example 1

[0029] A method for preparing self-compacting concrete based on modified slag comprises the following steps:

[0030] The self-compacting concrete based on modified water slag includes the following components by weight: 300g of P.O42.5 ordinary Portland cement, 100g of Class II active fly ash, 200g of modified water slag, 600g of machine-made sand, 900g of gravel, 170g of water, and 10g of early strength water reducing agent.

[0031] S1. 1000g of water slag was sieved through 14 mesh, 16 mesh, 18 mesh, 20 mesh and 24 mesh sieves, and the sieve residue water slag particle size was 0.71-1.4mm, mixed with 1g of calcium hydroxide, stirred with water, and cured for 7d to obtain the modified water slag for standby use;

[0032] S2. Add 0.2g of sodium sulfate to 9.8g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0033] S3. Cement, fly ash, machine-made sand and the modified water slag prepared in S1 were weighed according to the required proportion, mixed evenly, the early strength water reducer prepared in S2 and water were added, mixed again, gravel was added, and stirred for 2 minutes to obtain the self-compacting concrete based on the modified water slag.

[0034] Example 2

[0035] A method for preparing self-compacting concrete based on modified slag comprises the following steps:

[0036] The self-compacting concrete based on modified slag includes the following components by weight: 300g of P.O42.5 ordinary Portland cement, 100g of Class I active fly ash, 200g of modified slag, 600g of machine-made sand, 900g of gravel, 170g of water, and 10g of early strength water reducing agent.

[0037] S1. 1000g of water slag was sieved through 16 mesh and 18 mesh sieves, the sieve residue water slag particle size was 1.0-1.18mm, mixed with 2g of calcium oxide, stirred with water, and cured for 7d to obtain the modified water slag for standby use;

[0038] S2. Add 0.2g of potassium sulfate to 9.8g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0039] S3. Cement, fly ash, machine-made sand and the modified water slag prepared in S1 were weighed according to the required proportion, mixed evenly, the early strength water reducer prepared in S2 and water were added, mixed again, gravel was added, and stirred for 3 minutes to obtain the self-compacting concrete based on the modified water slag.

[0040] Example 3

[0041] A method for preparing self-compacting concrete based on modified slag comprises the following steps:

[0042] The self-compacting concrete based on modified water slag includes the following components by weight: 300g of P.O42.5 ordinary Portland cement, 100g of Class II active fly ash, 200g of modified water slag, 600g of machine-made sand, 900g of gravel, 170g of water, and 10g of early strength water reducing agent.

[0043] S1. 1000g of water slag was sieved through 14 mesh, 16 mesh, 18 mesh, 20 mesh and 24 mesh sieves, and the sieve residue water slag particle size was 0.71-1.4mm, mixed with 3g of calcium hydroxide, stirred with water, and cured for 7d to obtain the modified water slag for standby use;

[0044] S2. Add 0.1g of sodium sulfate and 0.1g of potassium sulfate to 9.8g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0045] S3. Cement, fly ash, machine-made sand and the modified water slag prepared in S1 were weighed according to the required proportion, mixed evenly, the early strength water reducer prepared in S2 and water were added, mixed again, gravel was added, and stirred for 2 minutes to obtain the self-compacting concrete based on the modified water slag.

[0046] Example 4

[0047] A method for preparing self-compacting concrete based on modified slag comprises the following steps:

[0048] The self-compacting concrete based on modified water slag includes the following components by weight: 300g of P.O42.5 ordinary Portland cement, 100g of Class II active fly ash, 200g of modified water slag, 600g of machine-made sand, 900g of gravel, 170g of water, and 10g of early strength water reducing agent.

[0049] S1. 1000g of water slag was sieved through 16 mesh and 18 mesh sieves, the sieve residue water slag particle size was 1.0-1.18mm, mixed with 1g of calcium hydroxide, stirred with water, and cured for 7d to obtain the modified water slag for standby use;

[0050] S2. Add 0.2g of sodium sulfate to 9.8g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0051] S3. Cement, fly ash, machine-made sand and the modified water slag prepared in S1 were weighed according to the required proportion, mixed evenly, the early strength water reducer prepared in S2 and water were added, mixed again, gravel was added, and stirred for 2 minutes to obtain the self-compacting concrete based on the modified water slag.

[0052] Example 5

[0053] A method for preparing self-compacting concrete based on modified slag comprises the following steps:

[0054] The self-compacting concrete based on modified slag includes the following components by weight: 300g of P.O42.5 ordinary Portland cement, 100g of Class II active fly ash, 200g of modified slag, 600g of quartz sand, 900g of gravel, 170g of water, and 15g of early strength water reducing agent.

[0055] S1. 1000g of water slag was sieved through 16 mesh and 18 mesh sieves, the sieve residue water slag particle size was 1.0-1.18mm, mixed with 1g of calcium hydroxide, stirred with water, and cured for 7d to obtain the modified water slag for standby use;

[0056] S2. Add 0.3g of sodium sulfate to 14.7g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0057] S3. Cement, fly ash, machine-made sand and the modified water slag prepared in S1 were weighed according to the required proportion, mixed evenly, the early strength water reducer prepared in S2 and water were added, mixed again, gravel was added, and stirred for 2 minutes to obtain the self-compacting concrete based on the modified water slag.

[0058] Example 6

[0059] A method for preparing self-compacting concrete based on modified slag comprises the following steps:

[0060] The self-compacting concrete based on modified water slag includes the following components by weight: 300g of P.O42.5 ordinary Portland cement, 100g of Class II active fly ash, 200g of modified water slag, 600g of machine-made sand, 900g of gravel, 170g of water, and 10g of early strength water reducing agent.

[0061] S1. 1000g of water slag was sieved through 14 mesh, 16 mesh, 18 mesh, 20 mesh and 24 mesh sieves, and the sieve residue water slag particle size was 0.71-1.4mm, mixed with 1g of calcium hydroxide, stirred with water, and cured for 7d to obtain the modified water slag for standby use;

[0062] S2. Add 0.2g of potassium sulfate to 9.8g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0063] S3. Cement, fly ash, machine-made sand and the modified water slag prepared in S1 were weighed according to the required proportion, mixed evenly, the early strength water reducer prepared in S2 and water were added, mixed again, gravel was added, and stirred for 2 minutes to obtain the self-compacting concrete based on the modified water slag.

[0064] Comparative Example 1

[0065] A method for preparing self-compacting concrete comprises the following steps:

[0066] The self-compacting concrete includes the following components by weight: 300 g of P.O42.5 ordinary Portland cement, 100 g of Class II active fly ash, 100 g of mineral powder, 700 g of machine-made sand, 900 g of gravel, 170 g of water, and 10 g of early strength water reducing agent.

[0067] S1. Add 0.2g of sodium sulfate to 9.8g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0068] S3. Cement, fly ash, machine-made sand and mineral powder are weighed according to the required proportion, mixed evenly, the early strength water-reducing agent prepared in S1 and water are added, mixed again, gravel is added, and stirred for 2 minutes to obtain the self-compacting concrete.

[0069] Compared with Example 1, the main difference of this comparative example is that no modified water slag is added, and mineral powder and machine-made sand are used instead.

[0070] Comparative Example 2

[0071] A method for preparing self-compacting concrete comprises the following steps:

[0072] The self-compacting concrete includes the following components by weight: 300g of P.O42.5 ordinary Portland cement, 100g of Class II active fly ash, 200g of slag, 600g of machine-made sand, 900g of gravel, 170g of water, and 10g of early strength water reducing agent.

[0073] S1. Add water to 200g of slag and stir, cure for 7d, and set aside;

[0074] S2. Add 0.2g of sodium sulfate to 9.8g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0075] S3. Weigh cement, fly ash, machine-made sand and the slag prepared in S1 according to the required proportion, mix them evenly, add the early strength water-reducing agent prepared in S2 and water, mix again, add gravel, stir for 2 minutes, and obtain self-compacting concrete.

[0076] Compared with Example 1, the main difference of this comparative example is that an equal amount of untreated water slag is used to replace the modified water slag after screening and activator treatment.

[0077] Comparative Example 3

[0078] A method for preparing self-compacting concrete comprises the following steps:

[0079] The self-compacting concrete includes the following components by weight: 300 g of P.O42.5 ordinary Portland cement, 100 g of Class II active fly ash, 200 g of modified water slag, 600 g of machine-made sand, 900 g of gravel, 170 g of water, and 10 g of water reducing agent.

[0080] S1. 1000g of water slag was sieved through 14 mesh, 16 mesh, 18 mesh, 20 mesh and 24 mesh sieves, and the sieve residue water slag particle size was 0.71-1.4mm, mixed with 1g of calcium hydroxide, stirred with water, and cured for 7d to obtain the modified water slag for standby use;

[0081] S2. Take 10g of polycarboxylate water reducer and set aside;

[0082] S3. Weigh cement, fly ash, machine-made sand and the modified water slag prepared in S1 according to the required proportion, mix them evenly, add water reducer and water, mix again, add gravel, and stir for 2 minutes to obtain self-compacting concrete.

[0083] Compared with Example 1, the main difference of this comparative example is that an equal amount of polycarboxylate water-reducing agent is used to replace the early strength water-reducing agent containing inorganic salt.

[0084] Comparative Example 4

[0085] A method for preparing self-compacting concrete comprises the following steps:

[0086] The self-compacting concrete includes the following components by weight: 300g of P.O42.5 ordinary Portland cement, 100g of Class II active fly ash, 200g of modified water slag, 600g of machine-made sand, 900g of gravel, 170g of water, and 10g of early strength water reducing agent.

[0087] S1. 1000g of slag was sieved through 14 mesh, 16 mesh, 18 mesh, 20 mesh and 24 mesh sieves, and the sieve residue slag particle size was 0.71-1.4mm, water was added and stirred, and cured for 7d to obtain the modified slag for standby use;

[0088] S2. Add 0.2g of sodium sulfate to 9.8g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0089] S3. Weigh cement, fly ash, machine-made sand and modified slag prepared in S1 according to the required proportion, mix them evenly, add the early strength water-reducing agent prepared in S2 and water, mix again, add gravel, stir for 2 minutes, and obtain self-compacting concrete.

[0090] Compared with Example 1, the main difference of this comparative example is that the modified water slag is not treated with an activator.

[0091] Comparative Example 5

[0092] A method for preparing self-compacting concrete comprises the following steps:

[0093] The self-compacting concrete includes the following components by weight: 300g of P.O42.5 ordinary Portland cement, 100g of Class II active fly ash, 200g of modified water slag, 600g of machine-made sand, 900g of gravel, 170g of water, and 10g of early strength water reducing agent.

[0094] S1. 1000g of water slag with a particle size of 0-30mm was mixed with 1g of calcium hydroxide, stirred with water, and cured for 7d to obtain the modified water slag for use;

[0095] S2. Add 0.2g of sodium sulfate to 9.8g of polycarboxylate water reducer to obtain an early strength water reducer for standby use;

[0096] S3. Weigh cement, fly ash, machine-made sand and modified slag prepared in S1 according to the required proportion, mix them evenly, add the early strength water-reducing agent prepared in S2 and water, mix again, add gravel, stir for 2 minutes, and obtain self-compacting concrete.

[0097] Compared with Example 1, the main difference of this comparative example is that the modified water slag is not subjected to screening treatment.

[0098] The above embodiments and comparative examples were subjected to performance tests, and the experimental test methods were as follows:

[0099] The slump, slump expansion and segregation rate of the concrete obtained in the above embodiments and comparative examples were tested with reference to the method specified in the "Technical Code for Application of Self-Compacting Concrete (JGJ_T283-2012)"; the compressive strength of self-compacting concrete at 3d, 7d, 28d and 56d was determined according to the relevant provisions of the "Standard for Test Methods for Physical and Mechanical Properties of Concrete (GB / T50081-2019)" using a specimen size of 100mm×100mm×100mm.

[0100] The result is as follows:

[0101] Table 1 Test results of self-compacting concrete performance of Examples 1-6 and Comparative Examples 1-5 of the present invention

[0102]

[0103]

[0104] As can be seen from Table 1, the self-compacting concrete based on modified slag prepared by the technical solution of the present invention, Examples 1-6 all have excellent fluidity, a segregation rate of no more than 6%, a 3d compressive strength greater than 25 MPa, a 28d compressive strength greater than 55 MPa, and a 56d strength greater than 60 MPa, showing excellent anti-segregation performance and strength. In Comparative Example 1, modified slag is not added, and mineral powder and machine-made sand are used instead. Although the compressive strength is acceptable among all comparative examples, the segregation rate is higher than 10%, showing poor anti-segregation performance; in Comparative Example 2, an equal amount of untreated slag is used to replace the modified slag after screening and activator treatment. Although the segregation rate is the lowest among all comparative examples, the compressive strength is also low; in Comparative Example 3, an equal amount of polycarboxylic acid water-reducing agent is used to replace the early strength water-reducing agent containing inorganic salts, and the early compressive capacity is low, indicating that the early strength effect is poor, which indirectly affects the later compressive strength growth, resulting in low compressive strength of the self-compacting concrete; in Comparative Example 4, the modified slag is not treated with an activator, and the hydration effect is insufficient. The self-compacting concrete obtained has poor anti-segregation performance and low compressive strength; in Comparative Example 5, the modified slag is not screened, and the self-compacting concrete obtained has the worst anti-segregation performance among all embodiments and comparative examples.

[0105] In summary, the present invention adopts modified slag to replace mineral powder and part of machine-made sand to prepare self-compacting concrete based on modified slag. By screening the slag, it is ensured that the slag particle size can match the particle grading of the self-compacting concrete, improve its fluidity and filling density, and continuously hydrate in the concrete system, so that the strength growth period is extended to more than 56 days, and it has excellent strength; the slag surface is treated with an activator, and an early strength reducing agent with an inorganic salt early strength agent is additionally added, so that the modified slag is more likely to undergo hydration reaction after contacting water, which can further improve the early strength of the self-compacting concrete based on the modified slag, significantly improve the density and impermeability of the self-compacting concrete based on the modified slag, enhance its strength and durability, and effectively extend its service life. The resulting self-compacting concrete based on modified slag has excellent fluidity, high strength, low-cost production advantages, outstanding environmental protection properties, excellent impermeability and high density, and is completely free of segregation, bleeding, slurry and sinking. The aggregate is evenly distributed, ensuring excellent durability and service life, and can meet higher-demand engineering application needs.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing self-compacting concrete based on modified slag, characterized in that: The following steps are involved: S1. The water residue was sieved through a 14-24 mesh sieve to obtain a particle size of 0.71-1.4mm of the sieve residue, mixed with an activator, stirred with water, and cured for 6-8d to obtain the modified water residue for standby use; S2. Add inorganic salt to the water reducing agent prepared in S2 to obtain an early strength water reducing agent for standby use; S3. Cement, fly ash, machine-made sand and the modified water slag prepared in S1 are weighed according to the required proportion, mixed evenly, early strength water reducer and water are added, mixed again, gravel is added, and stirred for 2-5 minutes to obtain the self-compacting concrete based on modified water slag.

2. A method for preparing self-compacting concrete based on modified slag according to claim 1, characterized in that: S1 The activator is calcium hydroxide and / or calcium oxide.

3. A method for preparing self-compacting concrete based on modified slag according to claim 1, characterized in that: The mass ratio of the screened water residue and the activator in S1 is 1:(0.0005-0.003).

4. A method for preparing self-compacting concrete based on modified slag according to claim 1, characterized in that: The sieves in S1 are 16 mesh and 18 mesh, and the particle size of the residual water slag is 1.0-1.18 mm.

5. A method for preparing self-compacting concrete based on modified slag according to claim 1, characterized in that: The water reducer described in S2 is a polycarboxylic acid-based water reducer; the inorganic salt described in S2 is sodium sulfate and / or potassium sulfate.

6. A method for preparing self-compacting concrete based on modified slag according to claim 1, characterized in that: The mass ratio of the water reducing agent and the inorganic salt in S2 is 1:(0.01-0.03).

7. A self-compacting concrete based on modified slag, characterized in that: It is prepared according to the method for preparing self-compacting concrete based on modified slag according to any one of claims 1 to 6.

8. A self-compacting concrete based on modified slag according to claim 7, characterized in that: Calculated by weight, the composition includes: 250-350 parts by weight of cement, 80-120 parts by weight of fly ash, 150-300 parts by weight of modified slag, 550-700 parts by weight of machine-made sand, 850-950 parts by weight of gravel, 155-180 parts by weight of water, and 7-15 parts by weight of early strength water reducing agent.

9. A self-compacting concrete based on modified slag according to any one of claims 7 to 8, characterized in that: Used to prepare concrete.

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