Superfine activated stone powder admixture hydraulic concrete and preparation method thereof

Abstract

The invention relates to hydraulic concrete with a superfine activated stone powder admixture. The hydraulic concrete is prepared from the following components in parts by weight: 4-8 parts of superfine inert stone powder, 0.1-0.5 part of an activating agent, 2-4 parts of inorganic active powder, 8-35 parts of cement, 65-80 parts of sand, 120-170 parts of stones, 1-5 parts of a water reducing agent, 0.01-0.05 part of an air entraining agent and 8-15 parts of water. According to the invention, mechanical activation of the stone powder and chemical modification of the mud scraps are cooperated to improve the activity of the stone powder in the concrete, and an inducer in a wet grinding process is utilized to exert the excitation effect of the stone powder under a certain particle size, so that the active reaction is enhanced, and the concrete admixture can be replaced; micron-sized inert stone powder and inorganic active powder are compounded to prepare a continuous-grading superfine composite admixture, and the superfine composite admixture replaces fly ash to be doped into concrete to prepare hydraulic concrete.

Description

Technical Field

[0001] The invention belongs to the field of hydraulic concrete, and particularly relates to hydraulic concrete with an ultra-fine activated fossil powder admixture and a preparation method thereof. Background Art

[0002] Traditional hydraulic concrete mainly relies on cement with low hydration heat to reduce the temperature rise of the dam. Fly ash, as a traditional concrete admixture, replaces part of the cement to achieve the purpose of reducing the hydration heat, thus solving the problem of high hydration temperature of large-volume hydraulic concrete. However, with my country's increasing emphasis on environmental protection, the number of thermal power plants producing fly ash is decreasing. Sorted, high-quality fly ash is in short supply, leading to a phenomenon in the process market where inferior fly ash is substituted for superior quality. This phenomenon is exacerbated by the availability of various low-quality fly ashes, including virgin coarse ash, ground fly ash, desulfurized fly ash, denitrified fly ash, floating black fly ash, and adulterated fly ash. The quality of these low-quality fly ashes has deteriorated, potentially leading to reduced concrete performance. Therefore, there is an urgent need to find alternative fly ash admixtures that can reduce the hydration temperature rise of concrete and compensate for the low early strength of fly ash-containing concrete. Summary of the Invention

[0003] In view of this, the present invention aims to propose a hydraulic concrete with ultra-fine activated fossil powder admixture and a preparation method thereof. The use of finely ground stone powder to prepare hydraulic concrete can reduce the pressure on the environment caused by a large amount of waste stone powder and industrial waste residue, reduce the amount of cement used, and improve the performance of concrete, reduce its comprehensive cost throughout its life cycle, and improve the overall benefits in terms of economy, energy, durability, ecology and environment. To achieve the above object, the technical solution of the present invention is achieved as follows: Disclosed is a hydraulic concrete with ultrafine activated fossil powder admixture. The hydraulic concrete comprises the following components: 4-8 parts of ultrafine inert stone powder, 0.1-0.5 parts of an activator, 2-4 parts of inorganic active powder, 8-35 parts of cement, 65-80 parts of sand, 120-170 parts of gravel, 1-5 parts of a water reducer, 0.01-0.05 parts of an air entraining agent, and 8-15 parts of water. Preferably, the inorganic active powder is slag powder or silicon powder, with a particle size between 0.2 μm and 2 μm and continuous gradation. Preferably, the fineness modulus of the sand is 2.0 to 3.0, and the gradation is continuous; the particle size of the gravel is 5 to 150 mm, and the gradation is continuous.

[0004] Preferably, the activator is mud powder and polyacrylamide in a mass ratio of 1: (0.01-0.03); the water reducer is a naphthalene-based water reducer or a polycarboxylic acid water reducer, and the air entraining agent is a rosin resin, an alkyl aromatic sulfonic acid or a fatty alcohol sulfonate.

[0005] Preferably, the ultrafine inert stone powder is processed from discarded materials of stone processing or sand and gravel processing system; the composite admixture composed of ultrafine inert stone powder and inorganic active powder has a particle size D(10): 0.1 micron; D(50): 1 micron; D(90): 10 microns, and the mechanically activated stone powder is obtained by grinding through dry-wet mixing method.

[0006] The ultrafine inorganic powder admixture hydraulic concrete and the method for preparing the ultrafine inert stone powder include the following steps: (1) Grind the rock or stone chips with a ball mill until they are less than 50 microns; (2) Add water and continue grinding in a wet ball mill until the particle size is below 1 μm. In this stage, add 50% of the composite inducer when the particle size is wet-milled to 20 μm. In the second stage, add the remaining composite inducer when the particle size is wet-milled to 5 μm to improve the bond breaking efficiency.

[0007] Preferably, the grinding medium is zirconium oxide fine particles Φ0.3-0.5 mm.

[0008] Preferably, the inducer in step 2) is a combination of Na₂SiO₃ and CaSO₄ in a mass ratio of (2.5-3.5):1, and the amount of inducer added is 0.5%-5% of the stone powder mass. During wet grinding, the solid-to-liquid ratio of the material to water is (2-4):1, and the mass ratio of zirconium oxide to inducer is (2-4):1. This prevents excessive inducer from causing an alkali-aggregate reaction. Using a stone powder activation technology based on the silicon (aluminum) oxygen bonding effect, the addition of an active inducer to stone powder below 10 microns breaks the silicon (aluminum) oxygen bonds on the surface, which then re-bond after a secondary pozzolanic reaction with cement hydration products.

[0009] Preferably, in step 2), 0.05%-0.25% Ca(OH)2 solution is added to the solution in the wet grinding tank to induce the rupture of the silicon-aluminum bonds on the surface of the stone powder and simultaneously generate CASH gel in situ without the need for subsequent alkali excitation.

[0010] Preferably, in the second stage of step 2), carbon dioxide is also introduced for 10-15 minutes before the second stage grinding is carried out. The carbon dioxide reacts with calcium hydroxide to produce calcium carbonate. In the later wet grinding process, a "tobermorite-like" transition phase is induced to form on the surface of the stone powder in a directional manner, solving the problem that the stone powder only serves as an "inert filler". The early strength is increased by more than 20%, and the later strength development is stable.

[0011] When the stone powder content exceeds 30%, the strength of conventional concrete drops sharply. However, due to the "nucleus-phase change" coupling effect, the 90d strength of the present invention exceeds that of the benchmark group (fly ash concrete) by 15%.

[0012] The present application has the following advantages: The present application provides a kind of ultra-fine inorganic powder admixture hydraulic concrete, each coarse, fine particle is filled in cement and its own void, improve the compactness of concrete, improve the compressive strength of concrete by grinding fine stone powder nucleation effect and filling theory, avoid excessive hydration heat, reduce hydration temperature rise while improving the durability of concrete such as frost resistance, impermeability and corrosion resistance.Inert stone powder and inorganic active powder play the role of adjusting the micro gradation of cementitious body and part of the activity of volcanic ash, and the water reducing agent is a retarding type.

[0013] Stone powder is mixed into cement as an inert admixture to make stone powder concrete, but the conventional stone powder fineness is 80 μm and the activity is not high, and the harmful components such as clay content in stone powder affect the performance of concrete, reduce the strength of concrete, which is the main reason for the limited amount of stone powder added. The present application improves the activity of stone powder in concrete by mechanical activation and chemical modification of stone powder, and uses an inducer in the wet grinding process to play its role in a certain particle size of stone powder, so that the activity reaction is enhanced to replace the admixture of concrete, and a kind of ultra-fine inorganic powder admixture hydraulic concrete is invented, which uses micron inert stone powder and inorganic active powder to prepare a continuous ultra-fine composite admixture, instead of fly ash to prepare hydraulic concrete.

[0014] The ultra-fine inert stone powder improves the full particle size gradation of concrete, increases the compactness of concrete, and plays the role of crystal nucleus to make the cement hydration reaction more sufficient; the chemical modification method of harmful substances in stone powder can adjust the early strength of concrete through ultra-fine inorganic active powder. The continuous gradation concrete composite admixture prepared according to the corresponding components and proportions is mixed into concrete in a certain proportion, which plays the role of water reducing, strengthening and densification, and can be used to prepare hydraulic concrete according to the design requirements of different concrete and the method of hydraulic mixture ratio design. The ultra-fine inert stone and inorganic active powder can replace fly ash, and the amount is calculated according to the proportion of cement in concrete, usually 15%-50%. DETAILED DESCRIPTION

[0015] Except for the defined, the technical terms used in the following examples and comparative examples have the same meaning as generally understood by those skilled in the art to which the present application belongs. The experimental reagents used in the following examples and comparative examples are conventional biochemical reagents unless otherwise specified; the experimental methods are conventional methods unless otherwise specified.

[0016] Example 1 Take the rock or stone chips and grind them into less than 100 microns with a ball mill, add a certain amount of water and put them into a wet ball mill to continue grinding until they are less than 5 microns. The grinding media is zirconium oxide fine particles Φ0.3-0.5mm and composite active inducer (Na2SiO3 and CaSO4 ratio is 3:1). According to the conventional mix ratio design method, the mix ratio parameters are: 42.5 cement 128kg / m 3 , ultra-fine stone powder 55kg / m 3 , S95 grade mineral powder 32kg / m 3 , activator 8kg / m 3 , sand 770kg / m 3 , crushed stone 1321kg / m 3 , water reducing agent 2.15kg / m 3 , air entraining agent 0.0215kg / m 3 , water 118kg / m 3 .

[0017] The activator is mud powder and polyacrylamide in a mass ratio of 1:0.02; the water reducer is polycarboxylic acid water reducer (Jiangsu Bote JM-PCA), and the air entraining agent is rosin resin (Shuangyi SYL-50).

[0018] The inorganic active powder is slag powder or silicon powder with a particle size between 0.2 μm and 2 μm and continuous gradation.

[0019] The composite admixture composed of ultrafine inert stone powder and inorganic active powder has a particle size of D(10): 0.1 micron; D(50): 1 micron; D(90): 10 microns, and is ground into mechanically activated stone powder by dry-wet mixing method.

[0020] The method for preparing ultrafine inert stone powder comprises the following steps: (1) Grind the rock or stone chips with a ball mill until they are less than 50 microns; (2) Add water and continue grinding in a wet ball mill until the particle size is below 1 μm. In this stage, add 50% of the composite inducer when the particle size is wet-milled to 20 μm. In the second stage, add the remaining composite inducer when the particle size is wet-milled to 5 μm to improve the bond breaking efficiency.

[0021] The grinding medium is zirconium oxide fine particles Φ0.3-0.5 mm.

[0022] The inducer is a composition of Na2SiO3 and CaSO4 in a mass ratio of 3:1, and the amount of inducer added is 3% of the mass of the stone powder; the solid-liquid ratio of the material and water during the wet grinding process is 3:1, and the mass ratio of zirconium oxide: inducer is 3:1.

[0023] Comparative Example 1 42.5 cement 150kg / m 3, fly ash 65kg / m 3 , sand 770kg / m 3 , crushed stone 1321kg / m 3 , water reducing agent 2.15kg / m 3 , air entraining agent 0.0215kg / m 3 , water 118kg / m 3 Obtained using conventional hydraulic concrete mix design method.

[0024] The ultrafine inorganic powder admixture hydraulic concrete prepared in Example 1 of the present invention uses ultrafine composite admixtures instead of conventional fly ash. The performance comparison of the concrete prepared and the concrete prepared in Comparative Example 1 is shown in Table 1.

[0025] Example 2 Based on Example 1, the difference is that (2) water is added and the mixture is placed in a wet ball mill and further ground to 10 μm. In this stage, 50% of the composite inducer is added when the mixture is wet-milled to 20 μm; in the second stage, the remaining composite inducer is added when the mixture is wet-milled to 15 μm. Other aspects are the same as in Example 1.

[0026] Example 3 Based on Example 1, the difference is that in step (2), 0.05%-0.15% Ca(OH)2 solution is added to the solution in the wet grinding tank, and the rest is the same as Example 1. Example 4 Based on Example 2, the difference is that in step (2), in the second stage, carbon dioxide is added and introduced for 10-15 minutes before continuing grinding. Example 5 Based on Example 4, MgO 20 kg / m 3 , the rest is the same as Example 4.

[0027] Table 1

[0028] Table 1 shows that, from a comprehensive perspective of concrete strength, deformation, thermal properties, and corrosion resistance, the use of staged grinding with the addition of a composite inducer and the addition of carbon dioxide during the second-stage wet grinding process, the introduction of nano-CaCO3, while simultaneously increasing the efficiency of the inert stone powder grinding and stimulating its activity, increased the early strength of the stone powder grinding by over 20%, and the strength continued to increase in the later stages. Furthermore, the expansion agent MgO was added to the mix ratio, and the high specific surface area of ​​the activated stone powder was utilized to adsorb the MgO expansion agent, offsetting autogenous shrinkage through delayed expansion. The 90-day drying shrinkage was reduced by 40%, and the self-volume deformation was micro-expansion, effectively compensating for concrete shrinkage. Therefore, the technical approach of staged wet grinding with an inducer and CO2, introducing a crystal form control agent and MgO, reduced cement usage while reducing the hydration temperature rise and volume deformation of the concrete compared to the concrete mixed with fly ash in Comparative Example 1. Furthermore, the compactness of the concrete was improved, the early strength of the concrete was enhanced, and the long-term durability properties of the concrete, such as frost resistance and impermeability, were improved. The particle size of Example 2 is different, which shows that the method for improving the grinding efficiency is to add a composite inducer within the appropriate grinding particle size range to maximize the efficiency of grinding and active reaction.

[0029] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A hydraulic concrete with ultrafine activated fossil powder admixture, characterized by: The hydraulic concrete comprises the following components: 4-8 parts of ultrafine inert stone powder, 0.1-0.5 parts of activator, 2-4 parts of inorganic active powder, 8-35 parts of cement, 65-80 parts of sand, 120-170 parts of gravel, 1-5 parts of water reducer, 0.01-0.05 parts of air entraining agent, and 8-15 parts of water.

2. The ultrafine inorganic powder admixture hydraulic concrete according to claim 1, characterized in that: The inorganic active powder is slag powder or silicon powder, with a particle size between 0.2 μm and 2 μm and continuous gradation.

3. The ultrafine inorganic powder admixture hydraulic concrete according to claim 1, characterized in that: The fineness modulus of the sand is 2.0-3.0, and the gradation is continuous; the particle size of the gravel is 5-150 mm, and the gradation is continuous.

4. The ultra-fine activated fossil powder admixture hydraulic concrete according to claim 1, wherein: The activator is mud powder and polyacrylamide in a mass ratio of 1: (0.01-0.03); the water reducer is a naphthalene-based water reducer or a polycarboxylic acid water reducer, and the air entraining agent is a rosin resin, an alkyl aromatic sulfonic acid or a fatty alcohol sulfonate.

5. The ultrafine inorganic powder admixture hydraulic concrete according to claim 1, characterized in that: The ultrafine inert stone powder is processed from discarded materials from a stone processing or sand and gravel processing system; the composite admixture composed of the ultrafine inert stone powder and the inorganic active powder has a particle size of D(10): 0.1 micron; D(50): 1 micron; D(90): 10 microns, and is ground by a dry-wet mixing method to obtain mechanically activated stone powder.

6. The ultrafine inorganic powder admixture hydraulic concrete according to any one of claims 1 to 5, characterized in that: The method for preparing ultrafine inert stone powder comprises the following steps: (1) Grind the rock or stone chips with a ball mill until they are less than 50 microns; (2) Add water and place in a wet ball mill to continue grinding until the particle size is less than 1 μm. In this stage, add 50% of the composite inducer when the particle size is wet-milled to 20 μm. In the second stage, add the remaining composite inducer until the particle size is 5 μm and the grinding is completed.

7. The ultrafine inorganic powder admixture hydraulic concrete according to claim 6, characterized in that: The grinding medium is zirconium oxide fine particles Φ0.3-0.5mm.

8. The ultrafine inorganic powder admixture hydraulic concrete according to claim 6, characterized in that: In step 2), the inducer is a composition of Na2SiO3 and CaSO4 in a mass ratio of (2.5-3.5):1, and the amount of the inducer added is 0.5%-5% of the mass of the stone powder; during the wet grinding process, the solid-liquid ratio of the material and water is (2-4):1, and the mass ratio of zirconium oxide to inducer is (2-4):

1.

9. The ultrafine inorganic powder admixture hydraulic concrete according to claim 6, characterized in that: In step 2), 0.05%-0.25% Ca(OH)2 solution is added to the solution in the wet grinding tank.

10. The ultrafine inorganic powder admixture hydraulic concrete according to claim 6, characterized in that: In the second stage of step 2), carbon dioxide is also introduced for 10-15 minutes before the second stage of grinding is carried out.

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