Concrete reinforcing agent and preparation method thereof

Abstract

The invention relates to a concrete reinforcing agent and a preparation method thereof. Slurry of the concrete reinforcing agent contains a large number of micro-gelling bodies formed by metakaolin particles. After the micro-gelling body in the concrete reinforcing agent slurry is doped into the concrete, the micro-gelling body structure forms uniformly-distributed micro-reinforcing points in the concrete, the micro-reinforcing points fill micro-pores in the concrete, the porosity of the concrete is reduced, the compactness of the concrete is improved, and meanwhile, in the setting and hardening process of the concrete, the micro-gelling body structure can be used for reinforcing the concrete. The micro-gelling body interacts with a concrete hydration product to form tighter chemical bonding, so that the comprehensive performance of the concrete is remarkably improved, the cost is reduced, and the micro-gelling body has a very good application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a concrete enhancer and a preparation method thereof. Background Art

[0002] In the construction industry, concrete is one of the most commonly used building materials, and the quality of its performance directly affects the quality and lifespan of buildings. In terms of strength, traditional concrete is difficult to meet the requirements for high load-bearing capacity in some super high-rise buildings, large bridges, etc.; in terms of durability, facing harsh natural environments (such as acid rain erosion, freeze-thaw cycles) and complex usage scenarios (such as chemical corrosion in chemical buildings), its service life is often short. Therefore, developing efficient concrete enhancement technologies has important practical significance.

[0003] In the Chinese patent with the publication number CN111704409A and the name "A C30 High-Impermeability Concrete with Low Cementitious Material Content and Its Preparation Method", a C30 high-impermeability concrete with low cementitious material content and its preparation method are disclosed. Each cubic meter of concrete includes components: 140 - 170 parts of cement, 40 - 60 parts of fly ash, 70 - 90 parts of slag powder, 15 - 25 parts of silica fume, 20 - 30 parts of stone powder, 18 - 22 parts of modified metakaolin, 490 - 520 parts of manufactured sand, 335 - 350 parts of river sand, 990 - 1020 parts of crushed stone, 5.1 - 6.1 parts of polycarboxylate water reducer, 165 - 175 parts of water, 15 - 25 parts of anti-cracking fiber; among them, the modified metakaolin is prepared by activation modification with gypsum, epoxy-based silane, and modified polystyrene. The C30 high-impermeability concrete with low cementitious material content provided by this invention has good impermeability performance. Overall, there is still room for performance improvement in this C30 high-impermeability concrete with low cementitious material content.

[0004] In the Chinese patent with the publication number CN106810186A and the name "A Compressive, Impermeable and Wear-Resistant Reinforced Concrete Drain Pipe Containing Water Glass and Its Preparation Method", a compressive, impermeable and wear-resistant reinforced concrete drain pipe containing water glass and its preparation method are disclosed. The raw materials include fly ash, slag powder, metakaolin, gypsum, sodium sulfate, naphthalene-based high-efficiency water reducer, sand, crushed stone, bisphenol A epoxy resin E-44, benzoyl peroxide, acrylic acid, N,N-dimethylethanolamine, organic montmorillonite, cement, steel fiber, calcined diatomaceous earth, steel bars, urea, methylsilanol sodium, potassium dichromate, water glass, etc. This invention prepares water-based epoxy resin by the method of graft copolymerization to obtain a network structure in which the polymer and the cement matrix material penetrate each other; at the same time, a uniform magnetic field is applied to the steel fiber concrete mixture to prepare unidirectionally distributed steel fiber concrete, with high fiber utilization rate and good strengthening effect. The cost of this invention's solution is relatively high, and the method of strengthening with steel fibers has application limitations.

[0005] In view of this, it is necessary to provide a concrete material with better performance, or for concrete materials, to provide a performance enhancer that can better improve the comprehensive performance of concrete. Summary of the Invention

[0006] The purpose of the present invention is to provide a concrete enhancer and its preparation method that can significantly improve the comprehensive performance of concrete.

[0007] To solve the above technical problems, the present invention discloses a concrete enhancer. A large number of micro-gel bodies formed by metakaolin particles are contained in the slurry of the concrete enhancer. After the micro-gel bodies in the slurry of the concrete enhancer are incorporated into the concrete, micro-enhancement points are evenly distributed inside the concrete in the micro-gel body structure. These micro-enhancement points fill the tiny pores inside the concrete, reduce the porosity of the concrete, and improve the density of the concrete. At the same time, during the setting and hardening process of the concrete, the micro-gel bodies interact with the hydration products of the concrete to form a closer chemical bond, significantly enhancing the comprehensive performance of the concrete;

[0008] The concrete enhancer is in paste form. The micro-gel bodies are formed by metakaolin fine particles with a particle size of 200 - 2000 meshes and water, and the micro-gel bodies are in a suspended state in the slurry.

[0009] A preparation method of a concrete enhancer includes the following steps:

[0010] S1. Mix metakaolin and water in a ratio of (0.5 - 1):1 to make the metakaolin particles in a suitable dispersion system;

[0011] S2. Put the metakaolin and water into a high-speed stirring device for stirring, and control the stirring speed at 50 revolutions per minute to 1100 revolutions per minute; continuously stir for 60 - 180 minutes.

[0012] Preferably, in S1, the SiO 2 content of the metakaolin is 45% - 55%, the Al 2 O 3 content is 40% - 48%, and the activity is 112 - 128.

[0013] Preferably, the particle size of the metakaolin is 200 meshes - 2000 meshes.

[0014] Preferably, in S2, the initial stirring speed is not greater than 100 revolutions per minute, and then the stirring speed is gradually increased.

[0015] Preferably, in S2, the temperature of the slurry is controlled at 20°C - 45°C during stirring.

[0016] Preferably, in S2, a magnetic field is present inside the stirring container and the magnetic field strength is not less than 2300 gauss, so as to significantly affect the trace magnetic components in the kaolin particles during stirring.

[0017] Preferably, the magnetic field strength is within 2300 gauss - 18000 gauss.

[0018] Preferably, a strong magnet is provided on the stirring arm of the high - speed stirring device.

[0019] Preferably, strong magnets are provided at the bottom and side walls inside or outside the stirring container of the stirring device.

[0020] The concrete enhancer and its preparation method of the present invention have at least the following advantages:

[0021] 1. Through the innovative improved metakaolin micro - cementation technology, the present invention significantly improves the comprehensive performance of concrete, including mechanical properties such as compressive, flexural, and tensile strengths, and durability, and can meet the requirements of various high - standard building projects for concrete materials.

[0022] 2. The magnetic - field - assisted micro - cementation preparation method is efficient and pollution - free. It can not only effectively promote the formation of the micro - cementation effect, but also avoid the environmental pollution problems that may be brought by traditional chemical additives, meeting the development trend of green building materials.

[0023] 3. By adding only a small amount of the concrete enhancer to the concrete (only 10 - 30 kg per cubic meter of concrete), the performance of the concrete can be greatly improved, with little increase in the project cost budget. The raw materials used in the concrete enhancer are widely sourced and the cost is relatively low, having a high cost - performance ratio, being easy to be widely promoted and applied in the construction industry, and having broad market prospects and social benefits. Description of the Drawings

[0024] Figure 1 It is the test result of a specimen cured for 3 days.

[0025] Figure 2 It is the test result of a specimen cured for 7 days.

[0026] Figure 3 It is the test result of a specimen cured for 28 days. Detailed Description of the Invention

[0027] The following further elaborates on the present invention through examples, so that those skilled in the art can implement it with reference to the text of the specification.

[0028] It should be understood that the terms such as "having", "comprising", and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0029] A concrete enhancer, in which a large number of micro-gel bodies formed by metakaolin particles are contained in the paste of the concrete enhancer; after the micro-gel bodies in the paste of the concrete enhancer are incorporated into the concrete, micro-enhancing points are formed in the concrete in a uniformly distributed manner. These micro-enhancing points fill the tiny pores inside the concrete, reduce the porosity of the concrete, and improve the compactness of the concrete. At the same time, during the setting and hardening process of the concrete, the micro-gel bodies interact with the hydration products of the concrete to form a tighter chemical bond, significantly enhancing the comprehensive performance of the concrete. The concrete enhancer is in a paste state, and the micro-gel bodies are in a suspended state in the paste. In addition, the dense structure of the concrete caused by the micro-gel bodies can effectively block the intrusion of harmful media such as external moisture, chloride ions, and sulfate ions, slow down the corrosion rate of the steel bars inside the concrete, and extend the service life of the concrete structure.

[0030] When the enhancer of the present invention is added to the concrete, the enhancement principle is that when the cement undergoes a hydration reaction, a large amount of hydration heat will be released. The metakaolin in the form of micro-gel bodies can play a certain buffering role in the concrete. The presence of the micro-gel bodies can block the hydration reaction of the cement particles spatially, reducing the probability of direct contact and reaction between the cement particles. The metakaolin micro-gel bodies can adsorb part of the free water participating in the hydration reaction, thereby slowing down the hydration rate of the cement. Since the generation rate of the hydration heat is closely related to the hydration speed of the cement, in this way, the generation rate of the hydration heat can be effectively reduced, avoiding defects such as cracks caused by too high temperature inside the concrete.

[0031] Moreover, a certain amount of water can be stored inside the metakaolin in the form of micro-gel bodies. During the setting and hardening process of the concrete, as the internal humidity decreases, the water in the micro-gel bodies will be gradually released. This slowly released water can provide the necessary conditions for the continuous hydration of the cement and play a role in self-curing.

[0032] In addition, the presence of the micro-gel bodies can also reduce the evaporation channels of the water inside the concrete. It can close the pores in the concrete to a certain extent, reduce the speed of water loss, so that the inside of the concrete can maintain a relatively humid environment for a long time, which is beneficial to the continuous growth of the concrete strength and the improvement of the durability.

[0033] A preparation method of a concrete enhancer, comprising the following steps:

[0034] S1. Mix metakaolin and water in a ratio of (0.5 - 1):1 to make the metakaolin particles in a suitable dispersion system;

[0035] S2. Metakaolin and water are put into a high-speed stirring device for stirring, and the stirring speed is controlled at 50 revolutions per minute to 1100 revolutions per minute; stirring is continued for 60 - 180 minutes. The specific operation is as follows: Slowly add the prepared kaolin powder into water according to a predetermined ratio, start the mechanical stirring device and adjust the rotation speed. During the stirring process, the changes in parameters such as the temperature and viscosity of the slurry are monitored in real time, and appropriate adjustments are made according to the actual situation to ensure the smooth progress of the micro-gelation process. After the predetermined stirring time, stop stirring and sample the prepared micro-gelated kaolin slurry for testing. For example, use a microscope to observe the microscopic structural integrity of the micro-gel, use a particle size analyzer to detect the particle size distribution, and use a Zeta potential measuring instrument to measure the surface charge characteristics to ensure that the key indicators of the micro-gel meet the predetermined technical standards.

[0036] In S1, the SiO 2 content of the metakaolin is 45% - 55%, and the Al 2 O 3 content is 40% - 48%, and the activity is 112 - 128. The above ultrafine powder kaolin, as a basic raw material, has unique physical and chemical properties and can provide a good basis for the subsequent micro-gelation process.

[0037] The particle size of the metakaolin is between 200 mesh and 2000 mesh.

[0038] In S2, the initial stirring speed is not greater than 100 revolutions per minute, and then the stirring speed is gradually increased.

[0039] In S2, the temperature of the slurry is controlled at 20°C - 45°C during stirring. At a lower stirring speed (such as 50 revolutions per minute), the kaolin particles move slowly in the slurry, the collision frequency is low, and the mutual adsorption effect between particles is weak, resulting in larger and fewer micro-gel particles formed. As the stirring speed increases to more than 800 revolutions per minute (for example, 1100 revolutions per minute), the particles move rapidly and collide frequently, and the adsorption effect between particles is enhanced, resulting in smaller and more micro-gel particles formed. The stirring time also has a significant impact on the formation of micro-gel. When the stirring time is 60 minutes, the micro-gel begins to form initially, but the structure is not perfect; when the stirring time is extended to 180 minutes, the micro-gel structure is denser and more stable, and the particle distribution is more uniform. Temperature has a key impact on the formation of micro-gel. When the temperature is at a relatively low level of 20°C, the molecular thermal motion is relatively slow, and the chemical reaction rate between kaolin particles also decreases accordingly. This will not only lead to a slower formation speed of the micro-gel, but also the formed micro-gel structure is not compact enough, and the binding force between particles is weak, ultimately affecting the stability and performance of the micro-gel.

[0040] As the temperature rises to 45°C, the thermal motion of molecules intensifies, the collision frequency and reaction activity between particles increase significantly, which can accelerate the formation rate of micro-gels and make the micro-gel structure more compact. However, when the temperature exceeds 45°C, it can cause the water in the slurry to evaporate too quickly, change the rheological properties of the slurry, disrupt the dispersion state of kaolin particles, and then affect the uniformity of micro-gels, making it impossible to effectively promote the formation of micro-gels with a microscopic structure.

[0041] In S2, a magnetic field is made to exist inside the stirring container with a magnetic field intensity not less than 2300 Gauss, so as to have a significant impact on the trace magnetic components in kaolin particles during stirring. During specific operation, it is necessary to conduct debugging of the stirring equipment and magnetic field setting:

[0042] a. Debug the mechanical stirring equipment to ensure the stability and controllability of the stirring speed, and be able to accurately control it within the predetermined stirring speed range.

[0043] b. Through a precise magnetic field intensity measuring instrument, ensure that the magnetic field intensity inside the stirring container is within 2300 Gauss - 18000 Gauss, and the uniformity of the magnetic field distribution meets the technical requirements.

[0044] When the kaolin slurry is in this magnetic field environment, the trace magnetic components in kaolin particles (such as magnetic impurities like iron and manganese, although the content is small, but sufficient to be affected by the magnetic field) will be affected by the magnetic field force. Although the metakaolin particles themselves have weak magnetism, they will also generate a magnetic dipole moment under the action of the magnetic field, prompting them to be arranged orderly along the magnetic field direction. This oriented arrangement greatly promotes the contact probability and adsorption effect between particles, further strengthening the micro-gel effect and making the micro-gel structure more stable and perfect.

[0045] The magnetic field can be arranged as follows: at the bottom of the stirring container, the S pole and N pole are alternately arranged in a ring, so that the magnetic field direction formed at the bottom of the container will be perpendicular to the bottom surface upward or downward; on the side wall of the stirring container, the magnets are arranged in a staggered up and down manner, so that the magnetic field direction surrounds along the side wall. The magnetic blocks on the stirring arm are arranged according to the rotation direction of the stirring arm. When the stirring arm rotates clockwise, the polarities of the magnetic blocks are arranged in a certain order in turn, so that the magnetic field force continuously acts on the kaolin particles during stirring, guiding the orderly movement of the particles. This enables the metakaolin particles to always be affected by a stable and effective magnetic field force during the entire stirring process, maximizing the orderly arrangement of the trace magnetic components in the particles, and then strengthening the micro-gel effect.

[0046] Placing a magnet on the stirring rod enables the stirring rod to directly apply a magnetic field force to the surrounding kaolin particles during rotation. When the stirring rod rotates, the magnetic field around it will also rotate, generating a dynamic magnetic field effect on the particles. This dynamic magnetic field can more effectively prompt the rotation and migration of trace magnetic components within the kaolin particles, accelerating the directional arrangement of the particles. Compared with only setting magnets on the wall and bottom of the stirring container, the magnet on the stirring rod can act on the particles at a closer distance, enhancing the influence effect of the magnetic field on the particles. The particles near the stirring rod will align along the magnetic field direction faster, and driven by the stirring rod, the mixing of the particles is more sufficient, further increasing the contact probability and adsorption effect between the particles, enabling the micro-gelation structure to form faster, more stably, and more perfectly during the stirring process.

[0047] In addition, in order to obtain an ultra-high magnetic flux with a smaller volume, the magnetic blocks are arranged in the form of a Halbach Array. Through special S and N pole settings, the magnetic field on one side can be significantly enhanced to more than 18,000 Gauss.

[0048] It is worth noting that due to reasons such as containing a small amount of metal ions, the slurry has a certain micro-conductivity. When the stirring rod cuts the magnetic induction line, it will carry charges or even generate a micro-current; the charged particles in the slurry play a positive role in the formation of micro-gelation in the magnetic field. The charged particles will be affected by the Lorentz force in the magnetic field, which will change the movement trajectory of the particles, making the collisions between the particles more orderly and frequent. This orderly collision can increase the opportunity of chemical bonding between the particles, contributing to the faster and more uniform formation of micro-gel. At the same time, the electrostatic interaction between the charged particles can also adjust the dispersion state of the particles, making it easier to aggregate and form a stable micro-gel structure in the magnetic field environment, thereby promoting the formation and growth of micro-gel and improving the quality and performance of micro-gel.

[0049] Concrete preparation and performance testing:

[0050] The prepared micro-gelated metakaolin slurry is added to the ordinary concrete mix proportion according to a certain dosage ratio to prepare test concrete specimens. At the same time, a group of blank control specimens without adding micro-gelated kaolin slurry are prepared.

[0051] All concrete specimens are cured under standard conditions. After curing to the specified ages (such as 3 days, 7 days, 28 days, 90 days, etc.), the performance indicators of the concrete specimens, such as compressive strength, flexural strength, impermeability, and chloride ion erosion resistance, are tested respectively. Record and analyze the test data to verify the enhancement effect of the micro-gelated kaolin slurry on the concrete performance.

[0052] After experimental verification, after incorporating 5-15% (relative to the cement dosage) of the micro-cemented metakaolin slurry, the flexural strength and compressive strength of the concrete can be increased by more than 30% under standard curing conditions, and in extreme cases, it can even reach 150%.

[0053] For example: When preparing concrete using a general brand of P.O42.5 cement (concrete mix ratio: cement 1: water 0.49: natural sand 0.92: machine sand 2.76: crushed stone 4.87: fly ash 20.0%: slag powder 21.0%: admixture 1.9%: micro-cemented metakaolin slurry 5%, where the ratios of cement, water, natural sand, machine sand, and crushed stone are by mass, while fly ash, slag powder, admixture, and micro-cemented metakaolin slurry are ratios relative to the cement dosage, this is the commonly used formulation expression in the industry), we mix the micro-cemented metakaolin slurry and the cement in the concrete at a ratio of 5:100, and use the standard curing method (temperature 20±2°C, relative humidity above 95%) for curing times of 3 / 7 / 28 days, and the test results are as Figures 1-3 shown. In addition, at 56 days of curing, we compared the compressive strength of the specimen with the specimen without adding the micro-cemented metakaolin slurry, and found that the compressive strength of the specimen after adding the micro-cemented metakaolin slurry increased by more than 80%, and the flexural strength increased by more than 30%. It can be seen that the micro-cemented metakaolin slurry has an obvious effect on improving the comprehensive performance of the concrete.

[0054] Although the embodiments of the present invention have been disclosed as above, it is not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A concrete reinforcing agent, characterized in that: The slurry of the concrete reinforcing agent contains a large amount of micro-gels formed by kaolin particles; after the micro-gels in the concrete reinforcing agent slurry are added to concrete, the micro-gel structure forms uniformly distributed micro-reinforcement points inside the concrete, and these micro-reinforcement points fill the tiny pores inside the concrete, reduce the porosity of the concrete, and improve the density of the concrete. At the same time, during the coagulation and hardening process of the concrete, the micro-gels interact with the hydration products of the concrete to form a tighter chemical bond, which significantly improves the comprehensive performance of the concrete; The concrete reinforcing agent is in the form of a paste, and the microgel is formed by 200-2000 mesh high-precision particles and water, and the microgel is in a suspended state in the paste.

2. A method for preparing the concrete reinforcing agent according to claim 1, characterized in that: The following steps are involved: S1. Mixing metakaolin and water in a ratio of (0.5-1):1 so that the metakaolin particles are in a suitable dispersion system; S2. Put kaolin and water into high-speed mixing equipment for mixing. The mixing speed of the concrete enhancer is controlled at 50 rpm to 1100 rpm and the speed is controlled according to time periods. The mixing is continued for 60-180 minutes.

3. The method for preparing a concrete reinforcing agent according to claim 2, characterized in that: In S1, the SiO2 content of the metakaolin is 45%-55%, the Al2O3 content is 40%-48%, and the activity is 112-128.

4. The method for preparing a concrete reinforcing agent according to claim 3, characterized in that: The particle size of the metakaolin is 200-2000 mesh.

5. The method for preparing a concrete reinforcing agent according to claim 2, characterized in that: In S2, the initial stirring speed is no more than 100 rpm, and then the stirring speed is gradually increased.

6. The method for preparing a concrete reinforcing agent according to claim 2, characterized in that: In S2, the temperature of the slurry is controlled at 20°C-45°C during stirring.

7. The method for preparing a concrete reinforcing agent according to claim 2, characterized in that: In S2, a magnetic field is created inside the stirring container and the magnetic field strength is not less than 2300 Gauss, so as to significantly affect the trace magnetic components in the kaolin particles during stirring.

8. The method for preparing a concrete reinforcing agent according to claim 7, characterized in that: The magnetic field strength is within a range of 2300 gauss to 18000 gauss.

9. The method for preparing a concrete reinforcing agent according to claim 7, characterized in that: A strong magnet is arranged on the stirring arm of the high-speed stirring device.

10. The method for preparing a concrete reinforcing agent according to claim 9, characterized in that: A strong magnet is arranged on the bottom or side wall of the inner side or outer side of the stirring container of the stirring device.

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