A method for preparing high-performance concrete modified with granite powder

Abstract

This invention relates to the field of concrete preparation technology, and more particularly to a method for preparing high-performance concrete modified with granite powder, comprising: adding dried granite powder of ≤40 mesh to an epoxy resin emulsion and mixing to obtain modified epoxy resin; pretreating dried wood fibers with an alkaline solution, washing and drying them for later use; mixing dried granite powder of ≤200 mesh with polyester resin, potassium peroxide ethyl ketone, and cobalt drying agent solution to modify the pretreated wood fibers to obtain modified wood fibers; performing carbonation modification treatment on the ground granite powder by passing carbon dioxide and nitrogen gas through an alkaline solution; mixing the modified wood fibers, the treated granite powder, cement, fly ash, aggregates, water, and additives evenly, adding the modified epoxy resin and mixing evenly to prepare concrete; adding redispersible latex powder according to the fluidity of the concrete and mixing again to obtain high-performance concrete modified with granite powder.

Description

Technical Field

[0001] This invention relates to the field of concrete preparation technology, and in particular to a method for preparing high-performance concrete modified with granite powder. Background Technology

[0002] The production of manufactured sand generates a large amount of stone powder. If this stone powder is not used properly, it will cause environmental pollution and waste resources. The mineral composition of manufactured sand stone powder is the same as that of the parent rock, and it can replace cement or traditional mineral admixtures such as fly ash and slag powder as mineral admixtures in concrete preparation.

[0003] Mechanized sand and gravel powder can be broadly classified into two types based on their mineral composition: calcareous rock matrix powder and siliceous rock matrix powder. Generally, calcareous rock matrix powder has better compatibility with water-reducing agents than siliceous rock matrix powder. This is mainly because calcareous stone powder often has an island-like structure and low water absorption, while siliceous stone powder often has a layered hydrophilic structure and high water absorption, resulting in a higher water requirement for the stone powder. If the stone powder content is too high, it will lead to a viscous concrete mixture with low fluidity, thus affecting the strength and durability of the hardened concrete. Granite's main component is SiO2, belonging to siliceous rocks. The mica particles in its stone powder are thin and flaky, with low strength, easily fractured along joint surfaces, and have a complex and unique internal interlayer structure with strong adsorption properties, leading to a high water requirement for granite stone powder. Furthermore, granite is a low-activity stone powder; if directly used as a mineral admixture in concrete preparation, it will be detrimental to the concrete strength.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the present invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a method for preparing high-performance concrete modified with granite powder. Through physical modification, the effective contact area and specific surface area of ​​the granite powder are increased, thereby enhancing its filling effect. Through carbonation chemical modification, the surface morphology of the granite powder is changed, becoming rougher and requiring more water to cover the surface, which leads to reduced fluidity. However, due to the improved interface, the mechanical properties are enhanced. After processing, the granite powder, when used as an admixture, helps to improve mechanical properties and durability.

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

[0007] A method for preparing high-performance concrete modified with granite powder includes the following steps:

[0008] S01: Add dry ≤40 mesh granite powder to epoxy resin emulsion in a certain proportion, mix and stir for 15-20 minutes to obtain modified epoxy resin.

[0009] Preferably, step S01 specifically includes: sieving granite powder through a 40-mesh (425 micrometers) square-hole sieve; drying the sieved granite powder at 100–120°C for 10–15 hours, strictly controlling the water content in the granite powder to prevent the formation of air bubbles; then weighing the dried granite powder under a drying environment and adding it to the epoxy resin emulsion according to the specified ratio; mixing and stirring under drying conditions for 15–20 minutes to reduce the impact of tension, thereby obtaining the modified epoxy resin. Smaller particles (e.g., 425 micrometers) can be more uniformly dispersed in the epoxy resin, reducing particle accumulation or sedimentation, which helps to prepare a more uniform modified epoxy resin and improve its application effect in concrete.

[0010] Granite powder, as an inorganic filler, plays a reinforcing role in epoxy resin. Its fine particles, when mixed with epoxy resin emulsion, can improve the resin's hardness, rigidity, and compressive strength. Furthermore, granite powder can enhance the resin's abrasion resistance, impact resistance, and heat resistance, thereby improving the adhesion of epoxy resin to concrete, especially in cementitious matrices or other fillers, thus enhancing the effectiveness of modified epoxy resin as an interface material in concrete.

[0011] S02: Pre-treat the dried wood fibers with an alkaline solution, then wash and dry them for later use;

[0012] Preferably, in step S02, the dried wood fibers are added to a 5% NaOH solution and immersed in the alkaline solution for 2 to 2.5 hours at room temperature; the immersed wood fibers are then removed and thoroughly rinsed with distilled water to remove the NaOH adhering to the surface of the wood fibers; the wood fibers are then placed in a constant temperature oven and dried at 100±5℃ for 20 to 30 hours to stabilize the fiber structure and ensure that it does not change during subsequent processing.

[0013] Wood fibers are mainly composed of cellulose, hemicellulose, and lignin, with cellulose being the primary structural component. The pretreatment of wood fibers with alkaline solution (NaOH) primarily involves alkaline hydrolysis, including lignin removal, hemicellulose hydrolysis, ring-opening, and partial degradation of cellulose. After alkaline treatment, NaOH disrupts the non-polar structure of the wood fibers, enriching the fiber surface with polar groups (such as hydroxyl and carboxyl groups). These polar groups can form hydrogen bonds or other interactions with other polar substances (such as water and resins), enhancing their adhesion to modified materials such as polyester resins and granite powder. Alkaline treatment also coarsens the surface of the wood fibers, increasing their specific surface area and improving interfacial bonding between the fibers and other materials, thereby enhancing the modification effect.

[0014] S03: Dry ≤200 mesh granite powder is mixed with polyester resin, potassium peroxide ethyl ketone and cobalt drying agent solution in a certain proportion to modify the wood fiber pretreated in step S02 to obtain modified wood fiber.

[0015] Preferably, step S03 specifically includes:

[0016] Granite powder is sieved through a 200-mesh (75-micron) square-hole sieve and dried at 100–120°C for 10–15 hours. A solution of polyester resin, methyl ethyl ketone peroxide, and cobalt drying agent is prepared and mixed with the dried granite powder at a ratio of 100:1–1.5:1–1.5:10–15. The mixture is stirred at low speed for 10–20 minutes to ensure uniform mixing. Wood fibers are soaked in the above mixture for 25–35 minutes, then spread on a smooth surface and pressed with a pressure plate at 20 kg. The mixture is cured at room temperature for 24 hours and then further cured at 60–85°C for 2 hours.

[0017] Wood fibers themselves contain components such as cellulose, hemicellulose, and lignin. Through impregnation with polyester resin, the active groups in the resin (such as hydroxyl and carbonyl groups) can chemically bond with the cellulose and hemicellulose components in the wood fibers, thereby enhancing the stability and bonding properties of the wood fibers. The presence of polyester resin can fill the voids in the wood fibers and enhance their structural strength after curing. Due to the synergistic effect of potassium peroxide ethyl ketone and cobalt drying agent, the resin layer on the surface of the wood fibers can cure rapidly, providing stronger surface adhesion and better mechanical properties. Granite powder, after being bonded by polyester resin and cured under pressure, bonds well with the surface of the granite powder, improving the tensile, bending, and impact resistance of the wood fibers. After modification, the fibers are relatively dispersed and spread evenly on the surface, eventually curing into long sheets, which are added last and stirred together to ensure dispersion.

[0018] S04: The ground granite powder is passed through an alkaline solution with carbon dioxide and nitrogen to carry out carbonation modification treatment.

[0019] Preferably, step S04 includes physical and chemical modification of the granite powder.

[0020] The physical modification involves drying granite powder in an oven at 100–120°C, cooling it, mixing it evenly with a grinding aid, and then grinding it in a ball mill. The grinding aid is prepared from triethanolamine and ethylene glycol in a mass ratio of 1:1, and the mass of the grinding aid is 0.2% of the mass of the granite powder.

[0021] The chemical modification is as follows: a 0.1 mol / L NaOH solution is prepared in a glass container (or other container where no reaction occurs), and the ground granite powder is added to the solution. Carbon dioxide and nitrogen are introduced into the NaOH solution at flow rates of 7–9 L / h and 3–5 L / h, respectively, for 60–80 minutes. The reaction is carried out at 25℃±5℃. After the reaction is completed, the mixture is separated into solid and liquid phases, and the separated solid is dried at 105℃ to constant weight.

[0022] Grinding granite powder results in smaller particle size and a higher specific surface area, which enhances its filling effect, reduces porosity, optimizes pore structure, and strengthens nucleation after subsequent chemical modification. Granite powder contains a small amount of CaO, which can be fully utilized for surface modification after chemical modification. When CO2 is introduced into granite powder in an aqueous environment, some CaO is converted to CaCO3 and precipitates due to its low solubility, adsorbing onto the granite powder surface. This not only increases the surface roughness of the granite powder, improving its bonding ability in cement, but also, due to the calcite structure on the surface, acts similarly to limestone powder in nucleation, improving the hydration degree of cement.

[0023] S05: Mix the modified wood fiber obtained in step S03, the granite powder treated in step S04, cement, fly ash, aggregate, water and additives evenly, and then add the modified epoxy resin obtained in step S01 and mix evenly to prepare concrete.

[0024] Preferably, in step S05, the aggregate includes ore and manufactured sand, the additive is a water-reducing agent, and the mass ratio of modified epoxy resin, modified wood fiber, treated granite powder, cement, fly ash, ore, manufactured sand, water and water-reducing agent is 28-31:6-9:55-65:230-250:55-65:980-1005:835-860:165-175:2.5-3.6.

[0025] Preferably, in step S05, manufactured sand and modified wood fiber are placed into a forced concrete mixer at a mass ratio of 1:10, then treated granite powder, cement, fly ash, remaining aggregate, water and water-reducing agent are added and the mixture is stirred for 2 minutes. Finally, modified epoxy resin is added and wet-mixed for 2 minutes to obtain high-performance concrete modified with granite powder.

[0026] S06: Test the fluidity of the obtained concrete, add 0-1% of redispersible latex powder as cementitious material and stir again to obtain high-performance concrete modified with granite powder.

[0027] The amount of redispersible latex powder added is determined based on the fluidity of the resulting concrete. If the fluidity of the concrete is too low, 1% (2.8–3.1 parts) of redispersible latex powder can be added to the cementitious material, and the mixture should be stirred again for 2 minutes. If the fluidity is still too low, this operation should be repeated, but note that the total amount of redispersible latex powder should not exceed 3% of the cement content. For every 12 mm that the concrete slump is lower than the design value, 1% (2.8–3.1 parts) of redispersible latex powder can be added for trial mixing. The introduction of redispersible latex powder will introduce a large number of air bubbles, reducing mechanical properties. To eliminate this effect, a defoamer is introduced to improve the mechanical properties of the concrete. For every 1 part of redispersible latex powder added, 0.01 parts of defoamer should be added. Taking GP330 defoamer as an example, its chemical formula is C 31 H 39 N4O 10 .

[0028] The beneficial effects of this invention are as follows:

[0029] In addition to modifying the granite powder itself, this invention utilizes the excellent synergistic effect between granite powder, epoxy resin, and wood fiber to prepare modified epoxy resin and modified wood fiber. Modifying wood fiber with granite powder helps reduce the water absorption rate of the wood fiber, improves thermal stability, and enhances tensile, flexural, and impact resistance, thus contributing to its better performance in concrete. Modifying epoxy resin with granite powder increases its water absorption rate, making it a highly absorbent material with excellent water absorption and desorption properties. When the relative humidity inside the concrete decreases, the absorbent material can release the absorbed water, supplementing the water consumed for hydration, ensuring the continuous formation of hydration products, filling the pores of the concrete, and reducing the adverse effects of micro-crack formation, drying shrinkage, and autogenous shrinkage, achieving the effect of internal curing. The preparation of modified epoxy resin as an admixture and modified wood fiber as an additive fiber improves the strength and durability of concrete.

[0030] In this invention, after trial mixing, the flowability of the concrete is adjusted using a combination of redispersible latex powder and defoamer to meet usage requirements. Various properties of the concrete are improved through chemical modification, physical grinding, particle packing, and the addition of admixtures. This addresses issues such as granite powder reducing concrete flowability, low hydration activity reducing hydration products and strength, and poor particle size distribution increasing porosity and reducing durability, resulting in high-performance granite powder concrete with excellent properties. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] Materials and commercial sources:

[0034]

[0035]

[0036] Example 1

[0037] A method for preparing high-performance concrete modified with granite powder includes the following steps:

[0038] S01: Granite powder is sieved through a 40-mesh (425 micrometers) square-hole sieve. The sieved granite powder is dried at 120°C for 12 hours, and the water content in the granite powder is strictly controlled to prevent the formation of air bubbles. Then, the dried granite powder is weighed in a dry environment and added to the epoxy resin emulsion according to the formula. The mixture is stirred for 15 minutes under dry conditions to reduce the effect of tension, thereby obtaining the modified epoxy resin.

[0039] S02: Add the dried wood fibers to a 5% NaOH solution and immerse the dried wood fibers in the alkaline solution for 2 hours at room temperature; remove the immersed wood fibers and rinse them thoroughly with distilled water to remove the NaOH adhering to the surface of the wood fibers; place the wood fibers in a constant temperature oven and dry them at 100±5℃ for 24 hours.

[0040] S03: Sieve the granite powder through a 200-mesh (75-micron) square-hole sieve, and dry the sieved granite powder at 120°C for 12 hours; prepare a solution of polyester resin, methyl ethyl ketone peroxide, and cobalt drying agent, and mix it with the dried granite powder in a ratio of 100:1:1:10; stir at low speed for 15 minutes to ensure uniform mixing; soak the wood fiber in the above mixture for 30 minutes, take it out and spread it on a smooth surface, use a pressure plate and apply 20 kg of pressure; cure at room temperature for 24 hours, and then further cure at 70°C for 2 hours;

[0041] S04: Dry the granite powder in an oven at 105℃, cool it, mix it evenly with the grinding aid, and then grind it in a ball mill; wherein, the grinding aid is prepared by triethanolamine and ethylene glycol in a mass ratio of 1:1, and the mass of the grinding aid is 0.2% of the mass of the granite powder; prepare a 0.1 mol / L NaOH solution in a glass container (or other non-reactive container), add the ground granite powder to the solution, and introduce carbon dioxide and nitrogen into the NaOH solution at gas flow rates of 8 L / h and 4 L / h, respectively, for 60 minutes. The reaction is carried out at 23℃. After the reaction is completed, the mixture is separated into solid and liquid, and the separated solid is dried at 105℃ to constant weight;

[0042] S05: The manufactured sand and modified wood fiber are placed in a forced concrete mixer at a mass ratio of 1:10. Then, the treated granite powder, cement, fly ash, remaining aggregate, water and water-reducing agent are added and the mixture is stirred for 2 minutes. Finally, the modified epoxy resin is added and wet-mixed for 2 minutes to obtain high-performance concrete modified with granite powder. The mass ratio of modified epoxy resin, modified wood fiber, treated granite powder, cement, fly ash, crushed stone, manufactured sand, water and water-reducing agent is 30:9:60:240:60:998:849:170:2.6.

[0043] S06: Test the fluidity of the obtained concrete, add 3% redispersible latex powder and 0.003% defoamer to the cementitious material and stir again to obtain high-performance concrete modified with granite powder.

[0044] Example 2: The difference between this example and Example 1 is that in step S03, the mixing ratio of polyester resin, methyl ethyl ketone peroxide, cobalt drying agent solution, and dried granite powder is changed to 100:1.5:1.5:15. Other details are omitted.

[0045] Example 3: The difference between this example and Example 1 is that in step S06, the amount of redispersible latex powder added is changed to 5%, and the amount of defoamer added is changed to 0.005%. Other details are omitted.

[0046] Comparative Example 1:

[0047] The difference between this embodiment and Embodiment 1 is that, in step S05, the mass ratio of modified epoxy resin, modified wood fiber, treated granite powder, cement, fly ash, ore, manufactured sand, water, and water-reducing agent is 0:0:60:240:60:998:849:170:2.6. Other details are omitted.

[0048] Comparative Example 2:

[0049] The difference between this embodiment and Embodiment 1 is that, in step S05, the mass ratio of modified epoxy resin, modified wood fiber, treated granite powder, cement, fly ash, crushed stone, manufactured sand, water, and water-reducing agent is 9:9:0:240:60:998:849:170:2.6. Other details are omitted.

[0050] Comparative Example 3:

[0051] The difference between this embodiment and Embodiment 1 is that, in step S05, the mass ratio of modified epoxy resin, modified wood fiber, treated granite powder, cement, fly ash, crushed stone, manufactured sand, water, and water-reducing agent is 9:9:0:240:60:998:849:170:2.6. No redispersible latex powder is added, resulting in high-performance concrete modified with granite powder.

[0052] Table 2. Performance Test Data

[0053]

[0054] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing high-performance concrete modified with granite powder, characterized in that, The following steps are included: S01: Add dry ≤40 mesh granite powder to epoxy resin emulsion in a certain proportion, mix and stir for 15~20 minutes to obtain modified epoxy resin. S02: Pre-treat the dried wood fibers with an alkaline solution, then wash and dry them for later use; S03: Dry granite powder with a mesh size of ≤200 is mixed with polyester resin, methyl ethyl ketone peroxide and cobalt drying agent solution in a certain proportion to modify the wood fiber pretreated in step S02 to obtain modified wood fiber. S04: The ground granite powder is passed through an alkaline solution with carbon dioxide and nitrogen to carry out carbonation modification treatment. S05: Mix the modified wood fiber obtained in step S03, the granite powder treated in step S04, cement, fly ash, aggregate, water and additives evenly, and then add the modified epoxy resin obtained in step S01 and mix evenly to prepare concrete. S06: Test the fluidity of the obtained concrete, add 0~1% of redispersible latex powder as cementitious material and stir again to obtain high-performance concrete modified with granite powder.

2. The method for preparing high-performance concrete modified with granite powder according to claim 1, characterized in that, Step S01 specifically includes: sieving granite powder through a 40-mesh sieve, drying the sieved granite powder at 100-120°C for 10-15 hours, weighing the dried granite powder and adding it to the epoxy resin emulsion according to the formula, mixing and stirring under drying conditions for 15-20 minutes to obtain the modified epoxy resin.

3. The method for preparing high-performance concrete modified with granite powder according to claim 1, characterized in that, Step S02 specifically includes: adding the dried wood fibers to a 5% NaOH solution and soaking them at room temperature for 2 to 2.5 hours; removing the wood fibers, rinsing them thoroughly with distilled water, and then placing them in an oven to dry at 100±5℃ for 20 to 30 hours.

4. The method for preparing high-performance concrete modified with granite powder according to claim 1, characterized in that, Step S03 specifically includes: sieving granite powder through a 200-mesh sieve, drying the sieved granite powder at 100-120℃ for 10-15 hours; preparing a solution of polyester resin, methyl ethyl ketone peroxide, and cobalt drying agent, and mixing it with the dried granite powder in a certain proportion; stirring at low speed for 10-20 minutes to ensure uniform mixing; immersing wood fibers in the above mixed solution for 25-35 minutes, removing them and spreading them on a smooth surface, applying 20kg of pressure using a pressure plate; curing at room temperature for 24 hours, and then further curing at 60-85℃ for 2 hours.

5. The method for preparing high-performance concrete modified with granite powder according to claim 4, characterized in that, In step S03, the mass ratio of polyester resin, methyl ethyl ketone peroxide, cobalt drying agent solution and dried granite powder is 100 : 1~1.5 : 1~1.5 : 10~15.

6. The method for preparing high-performance concrete modified with granite powder according to claim 1, characterized in that, Step S04 specifically includes: drying granite powder in an oven at 100~120℃, cooling it, mixing it evenly with a grinding aid, and then grinding it in a ball mill; preparing a 0.1 mol / L NaOH solution in a glass container, adding the ground granite powder to the solution, and introducing carbon dioxide and nitrogen into the NaOH solution at flow rates of 7~9L / h and 3~5L / h, respectively, for 60~80 minutes. The reaction is carried out at 20~30℃. After the reaction, the mixture is separated into solid and liquid phases, and the separated solid is dried at 100~120℃ to constant weight.

7. The method for preparing high-performance concrete modified with granite powder according to claim 6, characterized in that, In step S04, the grinding aid is prepared by triethanolamine and ethylene glycol in a mass ratio of 1:1, and the mass of the grinding aid is 0.2% of the mass of the granite powder.

8. The method for preparing high-performance concrete modified with granite powder according to claim 1, characterized in that, In step S05, the aggregates include ore and manufactured sand, the additive is a water-reducing agent, and the mass ratio of modified epoxy resin, modified wood fiber, treated granite powder, cement, fly ash, ore, manufactured sand, water and water-reducing agent is 28~31:6~9:55~65:230~250:55~65:980~1005:835~860:165~175:2.5~3.

6.

9. The method for preparing high-performance concrete modified with granite powder according to claim 8, characterized in that, Step S05 specifically includes: placing manufactured sand and modified wood fiber into a mixer at a mass ratio of 1:10, then adding treated granite powder, cement, fly ash, the remaining aggregate, water and water-reducing agent and continuing to mix, and finally adding modified epoxy resin for wet mixing to obtain high-performance concrete modified with granite powder.

10. The method for preparing high-performance concrete modified with granite powder according to claim 1, characterized in that, In step S06, the total amount of redispersible latex powder shall not exceed 3% of the cement, and 0.01 parts of defoamer shall be added for every 1 part of redispersible latex powder added.

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