Activated modified limestone powder as well as preparation method and application thereof

Abstract

The invention discloses activated modified limestone powder which is ball-milled powder of modified limestone-based slurry, and the modified limestone-based slurry comprises the following components in percentage by mass: 7-9.2% of an organic matter-based nucleating agent, 68-87% of limestone powder and 4.5-22.8% of silicon slag powder, the organic matter-based nucleating agent is prepared by the following steps: firstly, carrying out copolymerization reaction on styrene, methacrylic acid and isopentenyl polyoxyethylene ether to prepare a polymer emulsion, and then adding calcium salt and a sodium silicate solution to carry out room-temperature reaction. The activated and modified limestone powder has high hydration activity and fluidity ratio, can effectively compensate activity loss caused by fineness reduction on the premise that the grinding particle size is relatively large, remarkably reduces the grinding energy consumption and shortens the modification period; the activated modified limestone powder is applied to preparation of concrete, has good workability, mechanical properties, durability and the like, and is wide in applicability.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to an activated and modified limestone powder, a preparation method thereof, and an application thereof. Background Art

[0002] High-performance concrete has high strength, excellent workability, durability, and a wide range of application scenarios, and is widely used in modern buildings. High-performance concrete can withstand large loads, provide reliable support for building structures, and has significantly improved low porosity, impermeability, frost resistance, and chemical erosion resistance compared to ordinary concrete. It can resist harsh environments and effectively extend the service life.

[0003] Each year, a large amount of limestone is used to prepare machine-made sand. For the machine-made sand prepared by air separation and water washing methods, the mud content can be controlled below 1%. However, the by-product limestone powder per ton of limestone is as high as about 200 kg, which will cause problems such as a large accumulation of limestone powder, harming the ecological environment. Applying it to prepare concrete is a means of resource utilization of limestone powder; however, limestone powder has problems such as low activity and high mud content, which limit its application in concrete.

[0004] In view of the problems such as the large accumulation of limestone powder and low activity, it is urgent to further explore the method of activating and modifying limestone powder, and use it to ensure that the concrete has good workability, mechanical properties, and durability, so as to better serve various concrete structures. Summary of the Invention

[0005] The purpose of the present invention is to provide an activated and modified limestone powder in view of the deficiencies of the existing technology. Applying it to prepare high-performance concrete can take into account good workability, mechanical properties, and durability, and has a wide applicability.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] An activated and modified limestone powder, which is a ball-milled powder of a modified limestone-based slurry. In the modified limestone-based slurry, each component and its mass percentage include: 7-9.2% of an organic-based nucleating agent, 68-87% of limestone powder, and 4.5-22.8% of silica fume powder; the organic-based nucleating agent is first prepared by copolymerizing styrene, methacrylic acid, and isopentenyl polyoxyethylene ether to prepare a polymer emulsion, and then a calcium salt and a sodium silicate solution are added for a room-temperature reaction to obtain.

[0008] Preferably, the mass percentage of the limestone powder is 75-80%.

[0009] In the above solution, the molar ratio of styrene, methacrylic acid, and isopentenyl polyoxyethylene ether is 4-5:1:0.45-0.8.

[0010] Furthermore, the molecular weight of the isopentenyl polyoxyethylene ether is 2000 - 3500.

[0011] In the above solution, the copolymerization step adopts solution polymerization, and the solvent can be xylene (hydrophobic solvent), or ethanol and / or water solvent (hydrophilic solvent).

[0012] Furthermore, the dosage ratio of styrene to the solvent is 1 g: 4.5 - 5 mL.

[0013] In the above solution, the temperature of the copolymerization reaction is 60 - 80 °C, and the time is 6 - 12 h.

[0014] In the above solution, an initiator is introduced in the copolymerization reaction. Specifically, potassium persulfate (KPS), azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), etc. can be selected; its dosage accounts for 0.5 - 1% of the total mass of the three monomers of styrene, methacrylic acid and isopentenyl polyoxyethylene ether.

[0015] In the above solution, the copolymerization reaction is carried out under an inert atmosphere (such as nitrogen).

[0016] In the above solution, the molar ratio of the introduced styrene, calcium salt, and sodium silicate is 1: 0.1 - 0.15: 0.05 - 0.08.

[0017] In the above solution, the calcium salt can be selected from one or more of calcium chloride, calcium dihydrogen phosphate, etc.

[0018] In the above solution, the concentration of the sodium silicate solution is 4.5 - 5.5 wt%.

[0019] In the above solution, the room temperature reaction time is 10 - 30 min.

[0020] In the above solution, in the limestone powder, the CaCO3 content is below 65 wt%, the specific surface area is 340 - 355 m 2 / kg, and the density is 2.7 - 2.82 g / cm 3 , and the mud content is < 1 wt%.

[0021] In the above solution, in the silica residue powder, the SiO2 content is 80 - 85 wt%, the specific surface area is 320 - 325 m 2 / kg, and the density is 2.25 - 2.32 kg / m 3 .

[0022] The preparation method of the above activated modified limestone powder includes the following steps:

[0023] 1) Styrene, methacrylic acid and isopentenyl polyoxyethylene ether are added to a solvent for copolymerization reaction to prepare a polymer emulsion; then a calcium salt and a sodium silicate solution are added to the obtained polymer emulsion for reaction at room temperature to form calcium silicate hydrate (C-S-H) on the surface of polymer molecules, thus obtaining an organic-based nucleating agent.

[0024] 2) The obtained organic-based nucleating agent is mixed evenly with limestone powder and silicon slag powder to form a slurry, and a high-efficiency grinding aid is added for ball milling; after drying the product obtained by ball milling, it is vibrated and screened to obtain the activated and modified limestone powder.

[0025] Furthermore, purified styrene, methacrylic acid and isopentenyl polyoxyethylene ether are polymerized by solution polymerization to obtain an organic-based nucleating agent.

[0026] In the above scheme, the high-efficiency grinding aid contains diethylene glycol (DEG) and triisopropanolamine (TIPA), and the mass ratio of the two is 1:0.95 - 1.05; the dosage of the high-efficiency grinding aid is 0.03 - 0.05% of the total mass of limestone powder and silicon slag powder.

[0027] In the above scheme, the rotation speed used in the ball milling step is 150 - 180 r / min, and the time is 1.5 - 2 h.

[0028] In the above scheme, the volume of raw materials shall not exceed 3 / 4 of the volume of the ball milling tank, preferably 2 / 3 - 3 / 4, and the mass ratio of grinding balls to powder is 1.6 - 2:1.

[0029] In the above scheme, the drying temperature is 45 - 75 °C, and the time is 12 - 24 h.

[0030] In the above scheme, the sieve aperture for sieving is 200 mesh.

[0031] The specific surface area of the activated and modified limestone powder prepared according to the above scheme is 500 - 600 m 2 / kg, its 7-day activity index can reach 84.6%, its 28-day activity index can reach 86.2%, and the fluidity ratio is 89.4%, reaching the activity index of Class I fly ash.

[0032] When the activated and modified limestone powder described in the above scheme is applied to the preparation of high-performance concrete, when used alone, the dosage of the activated and modified limestone powder is 22 - 27% (percentage of the binder); the main hydration products of the obtained high-performance concrete include C-S-H gel, ettringite (AFt), calcium hydroxide (CH) and monocarboaluminate (Mc).

[0033] Preferably, the dosage of the activated and modified limestone powder is 24 - 25%.

[0034] Furthermore, in the high-performance concrete, each component and its weight fraction include: 340 - 382 parts of cement, 108 - 147 parts of activated and modified limestone powder, 730 - 836 parts of large-sized aggregates, 210 - 316 parts of small-sized aggregates, 701 - 756 parts of sand, 150 - 160 parts of water, and 5 - 6 parts of water reducer.

[0035] Furthermore, the cement can be PII 42.5 portland cement. The 28-day strength of the cement standard specimen is higher than 42.5 MPa, and the density is 3.05 - 3.18 g / cm 3 , and the specific surface area is 345 - 348 m 2 / kg.

[0036] Furthermore, the large-sized aggregates can be limestone with a particle size of 10 - 16 mm; the small-sized aggregates can be limestone with a particle size of 5 - 10 mm; the water absorption rate is 0.60 - 0.65%, and the bulk density is 3840 - 3950 kg / m 3 .

[0037] In the above solution, the sand can be natural river sand or manufactured sand, etc. Its fineness modulus is 3.0 - 3.1, the apparent density is 2715 - 2740 kg / m 3 , and the bulk density is 1680 - 1700 kg / m 3 .

[0038] In the above solution, the water reduction rate of the water reducer is more than 30%.

[0039] The principle of the present invention is:

[0040] The present invention effectively combines an organic-based nucleating agent with inorganic modified functional components such as silicon slag powder, and combines the mechanochemical action during the grinding process, which can significantly increase the free energy, surface activity, and dispersion ability of the particles on the surface of limestone powder, and realize the mineral admixture of limestone powder with high activity.

[0041] The organic-based nucleating agent first prepares a polymer emulsion through a copolymerization reaction of styrene, methacrylic acid, and isopentenyl polyoxyethylene ether. The introduced styrene can enhance the hydrophobicity and mechanical strength of the polymer, and at the same time improve the thermal stability of the polymer through π-π stacking. Methacrylic acid introduces functional groups such as carboxyl groups, providing highly active nucleation sites to promote the nucleation and growth of hydration products. Isopentenyl polyoxyethylene ether, through the hydrophilicity of its ether bond and long-chain structure, improves the dispersibility of particles and reduces the van der Waals force between particles through steric hindrance effects. Subsequently, a calcium salt and a sodium silicate solution are added to the polymer emulsion for a room-temperature reaction to in-situ generate calcium silicate hydrate (C-S-H) on the surface of polymer molecules, forming a nucleating agent with an organic-inorganic composite structure. This nucleating agent significantly enhances its interfacial bonding force with inorganic materials through the chemical bonding between carboxyl groups and calcium ions, as well as the nanostructure of C-S-H.

[0042] The obtained organic-based nucleating agent is mixed with limestone powder and silica residue powder to form a slurry, and a high-efficiency grinding aid is further introduced for ball milling, drying, vibrating, and screening to prepare activated modified limestone powder. During the ball milling process, the styrene groups in the organic-based nucleating agent can promote the uniform dispersion and surface modification of particles through hydrophobic interactions, and the π-electron system of the benzene ring can form a coordination bond with Ca 2 + in cement minerals to construct an organic-inorganic interface bridge, enhancing the interfacial bonding force between the modified limestone powder and the cement matrix. In addition, the introduction of styrene can reduce the surface energy of C3S and enhance the water molecule adsorption ability of C3S, significantly optimizing the interfacial microenvironment of the hydration reaction, and thus improving the strength of cement-based materials.

[0043] The surface of the obtained modified limestone powder has a composite structure of carboxyl groups, ether bonds, long-chain alkyl functional groups, and C-S-H. After modification, carboxyl groups (-COO-) and ether bonds (-O-) are introduced on the surface of the limestone powder, which ionize to generate negative charges in an alkaline environment to form a double-layer repulsion. At the same time, the long-chain alkyl functional groups form a spatial barrier of about 2-3 nm through physical extension, further preventing particle agglomeration. Through the electrostatic repulsion effect and steric hindrance effect, the dispersibility of particles and the fluidity of the slurry are significantly improved. At the same time, the multi-scale nucleation sites provided by the nucleating agent can accelerate the hydration reaction of cement clinker (such as C3S), promoting the rapid nucleation and growth of C-S-H gel and AFt, thereby improving the early strength of cement-based materials.

[0044] The obtained modified limestone powder can also react secondarily with calcium hydroxide (CH) in cement clinker and silicon dioxide (SiO2) in silica residue using its surface activity to generate more C-S-H gel and ettringite (AFt), further improving the strength of the cementitious material. Silica residue powder can provide an additional active silicon source and improve the solid-phase distribution.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] (1) The present invention uses low-calcium limestone powder and silica fume as the main raw materials, combines with an organic-based nucleating agent, a high-efficiency grinding aid, and a wet grinding process, and can prepare highly active modified limestone powder, taking into account relatively high hydration activity and fluidity ratio.

[0047] (2) The activated modified limestone powder of the present invention can effectively compensate for the activity loss caused by the reduction of fineness on the premise that the grinding fineness is relatively coarse (500 - 600 m 2 / kg), can significantly reduce the grinding energy consumption and shorten the modification cycle;

[0048] (3) The activated modified limestone powder of the present invention can replace admixtures such as fly ash to prepare high-performance concrete of C30 - C60 grade. Its hydration products include C-S-H gel, ettringite (AFt), calcium hydroxide (CH), and monocarboaluminate (Mc); the interface transition zone between its hardened cement paste and limestone is dense, and it is suitable for the preparation of large-volume concrete for pile caps and anchor piers, self-compacting underwater pile foundations, pier columns, precast prestressed beams, etc., with wide applicability;

[0049] (4) The preparation method involved in the present invention is relatively simple, easy to operate, can realize the resource utilization of industrial waste of low-calcium limestone, has significant economic and environmental benefits, and is suitable for popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 are the morphologies of the 7-day and 28-day hydration products of high-performance concrete obtained from a-b activated modified limestone powder and c-d unmodified limestone powder;

[0051] Figure 2 is a schematic diagram of the microscopic composition of the activated modified limestone powder system. DETAILED DESCRIPTION OF THE INVENTION

[0052] The technical solutions adopted in the present invention will be described in detail below through specific implementation examples. What is described is only a part of the present invention and does not represent all embodiments. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the instrument equipment adopted are all commercial products in this technical field.

[0053] In the following examples, the limestone powder used is provided by Panzhihua City, Sichuan Province, where the CaCO3 content is 65 wt%, the specific surface area is 342 m 2 / kg, the density is 2.82 g / cm 3 , and the mud content is < 1%.

[0054] The silica residue powder is produced in Panzhihua City, Sichuan Province. It is an industrial by-product generated from the smelting of silicon steel. After being purified and processed into powder, it has a large particle size and a low SiO2 content, and usually cannot be used as a mineral admixture. Its SiO2 content is 83 wt%, the specific surface area is 321 m 2 / kg, and the density is 2.3 g / cm 3 .

[0055] Example 1

[0056] An activated and modified limestone powder, and its preparation method includes the following steps:

[0057] 1) Add 10 g of styrene, 1.66 g of methacrylic acid, and 19.2 g of isopentenyl polyoxyethylene ether (molecular weight 2000) to 50 ml of ethanol, add 0.3 g of initiator AIBN, and carry out copolymerization reaction at 60 °C for 8 h to prepare a polymer emulsion with carboxyl functional groups on the surface. After gradually adding 1.07 g of calcium chloride and 11.8 ml of sodium silicate solution (concentration 5 wt%) to the emulsion, carry out a room temperature composite reaction for 30 min to form calcium silicate hydrate (C-S-H) on the surface of the polymer molecules, and obtain an organic-based nucleating agent;

[0058] 2) Mix 10 g of the organic-based nucleating agent (9.1%), 95 g of limestone powder (86.4%), 5 g of silica residue powder (4.5%), etc. to form a slurry, pour it into the ball mill tank equipped with grinding balls, and then add 0.04 g of a high-efficiency grinding aid (composed of diethylene glycol (DEG) and triisopropanolamine (TIPA) in a mass ratio of 1:1), and carry out ball milling at 150 r / min for 2 h. After the ball milling is completed, take out the grinding balls, dry them, vibrate them, and pass through a 200-mesh sieve to obtain the activated and modified limestone powder.

[0059] Example 2

[0060] An activated and modified limestone powder, and its preparation method is substantially the same as that of Example 1, except that the components and their dosages are as follows: 10 g of the organic-based nucleating agent, 85 g of limestone powder, and 15 g of silica residue powder.

[0061] Example 3

[0062] An activated and modified limestone powder, and its preparation method is substantially the same as that of Example 1, except that the components and their dosages are as follows: 10 g of the organic-based nucleating agent, 75 g of limestone powder, and 25 g of silica residue powder.

[0063] Comparative Example 1

[0064] An activated and modified limestone powder, and its preparation method is substantially the same as that of Example 2, except that: without adding the organic-based nucleating agent, mix the limestone powder and the silica residue powder and then carry out ball milling (the ball milling conditions are the same as those in Example 2).

[0065] Comparative Example 2

[0066] An activated modified limestone powder, the preparation method of which is substantially the same as that of Example 2, except that styrene is not added during the preparation of the organic-based nucleating agent.

[0067] Comparative Example 3

[0068] An activated modified limestone powder, the preparation method of which is substantially the same as that of Example 2, except that the preparation steps of the organic-based nucleating agent are as follows:

[0069] 10g of styrene, 1.66g of methacrylic acid and 19.2g of isopentylene polyoxyethylene ether (molecular weight 2000) were added to 50ml of ethanol, and 0.3g of initiator AIBN was added to carry out copolymerization reaction at 60°C for 8h to prepare a polymer emulsion with carboxyl functional groups on the surface; after 5.35g of calcium chloride and 59ml of sodium silicate solution (concentration of 5wt%) were gradually added to the emulsion, a composite reaction was carried out at room temperature for 30min to form calcium silicate hydrate (CSH) on the surface of the polymer molecules to obtain an organic-based nucleating agent.

[0070] The following table shows the activity test results of Examples 1 to 5 and Comparative Examples 1 to 3.

[0071] Table 1 Activity test results

[0072]

[0073] Application Examples

[0074] The activated modified limestone powder obtained in Example 2 was used as a mineral admixture to partially replace cement, and concrete was prepared according to different dosages (relative to the total mass of cementitious materials), wherein the dosages of the activated modified limestone powder were 22%, 25%, 27%, and 30% (respectively denoted as 1# to 4#), and compared with Class I (Ⅰ-FA) and Class II (Ⅱ-FA) concrete. The mix design of the high performance concrete is shown in 2, and the performance test results are shown in Table 3.

[0075] Table 2 Mix ratio of high performance concrete obtained with different mineral admixtures (kg / m 3 )

[0076]

[0077] Table 3 Performance indexes of high performance concrete with activated modified limestone powder single admixture system

[0078]

[0079]

[0080] As can be seen from Table 1, the strength change of concrete shows a trend of gradually decreasing compressive and flexural strength with increasing dosage. When the dosage is below 25%, the mechanical properties of concrete remain basically stable, and there is no significant difference in slump / extension compared with Class I fly ash and Class II fly ash. Using modified limestone powder to replace fly ash can not only increase the types of mineral admixtures, but also have better working performance while maintaining stable mechanical properties. In terms of strength, when the dosage is less than 25%, the compressive strength and flexural strength of 3d, 7d, and 28 days are better than those of Class II fly ash, reaching the level of Class I fly ash. In addition, the test group mixed with activated modified limestone powder has a faster development of 3d and 7d strength. The reason is that the addition of activated modified limestone powder can accelerate the hydration rate of cement clinker, and the addition of organic nucleating agents provides more nucleation sites, providing nucleation area for hydration products, and promoting the rapid nucleation and growth of hydration products on its surface. Nucleating agents can effectively promote cement hydration, increase the hydration rate, accelerate the formation of hydration products such as calcium aluminate, calcium hydroxide, and CSH gel, increase the proportion of solid phase, and accelerate the coagulation and hardening of cement paste. The particle size of limestone powder after ball milling is smaller, which can be filled into the gaps between cement particles and improve the pore structure of concrete hydration products. By optimizing the pore structure, the proportion of large pores in concrete can be reduced, the number of small pores can be increased, and the structure of concrete can be made more uniform and dense. The filling effect of limestone powder and the improvement of pore structure help to improve the strength and durability of concrete. In addition, due to the addition of ball-milled activated modified limestone powder, a large amount of Ca is introduced into the system. 2+ , resulting in a large amount of CH in the system, and the SiO2 in the activated modified limestone powder participates in the reaction to produce active silicon-oxygen tetrahedron [SiO4] - , promoting the formation of C-(A)-SH gel and AFt.

[0081] Dispersed CaCO3 particles act as nuclei for the hydration of cement clinker (such as C3S), promoting the cement hydration reaction. Cement hydration reaction is the basis for the development of concrete strength. Therefore, accelerating cement hydration reaction helps to improve the early strength of concrete. When the dosage is greater than 25%, the compressive strength gradually decreases. Compared with the fly ash group, when the dosage is 22%, the test strength basically reaches the strength level of Class I fly ash. When the dosage is 25%, the test strength is higher than Class II fly ash. Compared with Class I fly ash, the high-performance concrete prepared by single-mixing activated modified high-calcium limestone powder has a 28d compressive strength ratio of 97%.

[0082] When a proper amount of activated and modified limestone powder is singly doped, due to its hydration nucleation effect and filling effect, while promoting hydration, it fills the pores between the cementitious materials and aggregates, resulting in a dense structure and good volume stability. However, when the doping amount is relatively high, because its particles are finer than cement, excessive hydration will wrap around the surface of cement particles, which will hinder the hydration process to a certain extent, forming too many pores that cannot be filled, thus affecting strength and volume stability, etc.

[0083] Figure 1 Figures 4(a) and 4(b) are the morphology diagrams of the hydration products of high-performance concrete with activated and modified limestone powder and unactivated limestone powder systems at 7 days and 28 days. Since the design of high-performance concrete follows the maximum packing density theory, and under the action of a low water-binder ratio and a large amount of mineral admixtures, the overall microscopic hydration product distribution shows a dense and interlaced filling characteristic. From the hydration product structures in Figures 4(a) and 4(b), it can be seen that in the hydration products at 7 days, there are more flaky or CH formations, the C-S-H gel mostly exists in the form of fine fibers, and only a small amount of AFt exists in the form of needles; as the hydration progresses to 28 days, the hydration products increase significantly, and the C-S-H gel, AFt, and CH are interlaced and connected to form a tight network structure. Finally, in the unactivated limestone group, the overall degree of hydration is not high, a large number of CaCO3 particles are distributed on the surface of the cementitious system, and only a small amount of CH and C-S-H gel are generated. At 28 days later, only a small amount of needle-shaped AFt penetrates between the CH and C-S-H gel.

[0084] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and their purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. An activated modified limestone powder, characterized in that: The invention relates to a ball-milled powder of a modified limestone-based slurry. In the modified limestone-based slurry, each component and its mass percentage include: 7-9.2% of an organic-based nucleating agent, 68-87% of limestone powder, and 4.5-22.8% of silicon slag powder. The organic-based nucleating agent is firstly prepared by copolymerizing styrene, methacrylic acid and isopentyl polyoxyethylene ether to prepare a polymer emulsion, and then calcium salt and sodium silicate solution are added to react at room temperature to obtain the nucleating agent.

2. The activated modified limestone powder according to claim 1, characterized in that: The molar ratio of styrene, methacrylic acid and isopentenyl polyoxyethylene ether is 4-5:1:0.45-0.

8.

3. The activated modified limestone powder according to claim 1, characterized in that: The molecular weight of the isopentenyl polyoxyethylene ether is 2000-3500.

4. The activated modified limestone powder according to claim 1, characterized in that: The copolymerization reaction is carried out at a temperature of 60 to 80° C. and for a time of 6 to 12 hours.

5. The activated modified limestone powder according to claim 1, characterized in that: The molar ratio of the introduced styrene, calcium salt and sodium silicate is 1:0.1-0.15:0.05-0.

08.

6. The activated modified limestone powder according to claim 1, characterized in that: The calcium salt is one or more of calcium chloride and calcium dihydrogen phosphate; the concentration of the sodium silicate solution is 4.5-5.5wt%.

7. The method for preparing the activated modified limestone powder according to any one of claims 1 to 6, characterized in that: The following steps are involved: 1) adding styrene, methacrylic acid and isopentenyl polyoxyethylene ether into a solvent to carry out copolymerization reaction to prepare a polymer emulsion; then adding calcium salt and sodium silicate solution into the obtained polymer emulsion to carry out room temperature reaction to obtain an organic-based nucleating agent; 2) The obtained organic-based nucleating agent is uniformly mixed with limestone powder and silicon slag powder to form a slurry, and a high-efficiency grinding aid is added to perform ball milling; the ball milled product is dried, vibrated, and sieved to obtain the activated modified limestone powder.

8. The preparation method according to claim 7, characterized in that: The high-efficiency grinding aid comprises diethylene glycol and triisopropanolamine.

9. A high performance concrete prepared by using the activated modified limestone powder according to any one of claims 1 to 6, characterized in that: The amount of activated modified limestone powder is 22-27% of the total mass of the cementitious material.

10. The high performance concrete according to claim 9, characterized in that: The components and their weight proportions include: 340-382 parts of cement, 108-147 parts of activated modified limestone powder, 730-836 parts of large-size aggregate, 210-316 parts of small-size aggregate, 701-756 parts of sand, 150-160 parts of water, and 5-6 parts of water reducing agent.

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