Concrete reinforcing agent and method of making same

Abstract

The present application relates to a kind of concrete reinforcing agent and its preparation method, the slurry of the concrete reinforcing agent contains a large number of microgel formed by metakaolin particles;After the microgel in the slurry of concrete reinforcing agent is incorporated into concrete, the microgel structure forms evenly distributed micro-reinforcement points in the interior of concrete, these micro-reinforcement points fill the small pores in the interior of concrete, reduce the porosity of concrete, improve the density of concrete, at the same time, in the process of concrete setting and hardening, microgel interacts with concrete hydration product, forms more compact chemical bonding, significantly improves the comprehensive performance of concrete, reduces cost, has good application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building materials, and particularly relates to a concrete reinforcing agent and a preparation method thereof. BACKGROUND

[0002] In the construction industry, concrete is one of the most commonly used building materials, and its performance directly affects the quality and service life of the building. Traditional concrete is difficult to meet the demand for high bearing capacity of some super high-rise buildings, large bridges, etc. in terms of strength; in terms of durability, its service life is often short in the face of harsh natural environments (such as acid rain erosion, freeze-thaw cycle) and complex use scenarios (such as chemical corrosion in chemical construction). Therefore, it is of great practical significance to develop efficient concrete reinforcing technology.

[0003] A C30 high impermeability concrete with low cementitious material dosage and a preparation method thereof are disclosed in Chinese patent CN111704409A, which comprises the following components per m3 of concrete: cement 140-170 parts, fly ash 40-60 parts, mineral powder 70-90 parts, silica fume 15-25 parts, stone powder 20-30 parts, modified metakaolin 18-22 parts, machine-made sand 490-520 parts, river sand 335-350 parts, gravel 990-1020 parts, polycarboxylic acid water reducer 5.1-6.1 parts, water 165-175 parts, and anti-cracking fiber 15-25 parts. The modified metakaolin is prepared by excitation modification with gypsum, epoxy silane, and modified polystyrene. The C30 high impermeability concrete with low cementitious material dosage provided by the invention has good impermeability. Overall, there is still room for improvement in the performance of the C30 high impermeability concrete with low cementitious material dosage.

[0004] A water glass-containing compression-resistant, impermeability-resistant, wear-resistant reinforced concrete drainage pipe and a preparation method thereof are disclosed in Chinese patent CN106810186A. The pipe is prepared from fly ash, slag powder, metakaolin, gypsum, sodium sulfate, naphthalene-based superplasticizer, sand, gravel, bisphenol A type epoxy resin E-44, benzoyl peroxide, acrylic acid, N,N-dimethyl ethanolamine, organic montmorillonite, cement, steel fiber, calcined diatomite, steel reinforcement, urea, sodium methylsilanol, potassium dichromate, and water glass. The invention prepares a water-based epoxy resin through graft copolymerization, obtaining a network structure in which the polymer and the cement matrix material interpenetrate. At the same time, a unidirectional distribution of steel fiber concrete is prepared by applying a uniform magnetic field to the steel fiber concrete mixture, with high fiber utilization rate and good reinforcing effect. The invention has relatively high cost, and the steel fiber strengthening method has application limitations.

[0005] Therefore, it is necessary to provide a concrete material with better performance, or to provide a concrete comprehensive performance enhancer which can better improve the comprehensive performance of concrete. SUMMARY

[0006] The purpose of the present application is to provide a concrete enhancer which can significantly improve the comprehensive performance of concrete and a preparation method thereof.

[0007] To solve the above technical problems, the present application discloses a concrete enhancer, which contains a large number of micro-agglomerates formed by metakaolin particles in the slurry; after the micro-agglomerates in the concrete enhancer slurry are mixed into concrete, the micro-agglomerate structure forms uniformly distributed micro-enhancing points in the concrete, which fill the small pores in 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-agglomerates interact with the hydration products of the concrete to form tighter chemical bonds, thereby significantly improving the comprehensive performance of the concrete.

[0008] The concrete enhancer is in paste form, and the micro-agglomerates are formed by 200-2000 mesh metakaolin particles and water, and the micro-agglomerates are in a suspended state in the slurry.

[0009] A preparation method of a concrete enhancer, comprising 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 50-1100 rpm; continue stirring for 60-180 minutes.

[0012] Preferably, in S1, the SiO2 content of the metakaolin is 45%-55%, the Al2O3 content is 40%-48%, and the activity is 112-128.

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

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

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

[0016] Preferably, in S2, a magnetic field with a strength not less than 2300 Gauss is present in the stirring container to have a significant effect on the trace magnetic components in the metakaolin particles during stirring.

[0017] Preferably, the magnetic field strength is within a range of 2300 Gauss to 18000 Gauss.

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

[0019] Preferably, a strong magnet is provided on the bottom or side wall of the inner or outer side of the stirring container of the stirring device.

[0020] The concrete reinforcing agent and preparation method thereof of the present invention have at least the following advantages:

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

[0022] 2. The magnetic field-assisted microgelation preparation method is highly efficient and pollution-free. It not only effectively promotes the formation of the microgelation effect, but also avoids the environmental pollution problems that may be caused by traditional chemical additives, which is in line with the development trend of green building materials.

[0023] 3. Just add a small amount of concrete enhancer to the concrete (only 10-30kg per cubic meter of concrete) to significantly improve the performance of the concrete, without much increase in the project cost budget. The raw materials used in concrete enhancers are widely available and the cost is relatively low. It has a high cost-effectiveness and is easy to promote and apply on a large scale in the construction industry. It has broad market prospects and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Fig. 1 This is the inspection result of a sample cured for 3 days.

[0025] Fig. 2 This is the inspection result of a sample cured for 7 days.

[0026] Fig. 3 This is the inspection result of a sample cured for 28 days. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below through examples so that those skilled in the art can implement the invention with reference to the description.

[0028] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0029] A concrete reinforcing agent, which contains a large number of micro-aggregates formed by metakaolin particles in the paste; after the micro-aggregates in the concrete reinforcing agent paste are incorporated into the concrete, the micro-aggregate structure forms uniformly distributed micro-reinforcement points in the concrete, which fill the small pores in 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-aggregates interact with the hydration products of the concrete to form tighter chemical bonds, significantly improving the overall performance of the concrete. The concrete reinforcing agent is in paste form, and the micro-aggregates are in a suspended state in the paste. In addition, the dense structure of the concrete caused by the micro-aggregates can effectively block the intrusion of harmful media such as external water, chloride ions, and sulfate ions, slow down the corrosion rate of the steel bars inside the concrete, and prolong the service life of the concrete structure.

[0030] The principle of the reinforcing agent is that when the cement undergoes hydration reaction, a large amount of hydration heat is released, and the metakaolin micro-aggregates can play a certain buffering role in the concrete. The presence of micro-aggregates can spatially block the hydration reaction of cement particles, reducing the probability of direct contact and reaction between cement particles. The metakaolin micro-aggregates can adsorb part of the free water involved in the hydration reaction, thereby slowing down the hydration rate of the cement. Because the generation rate of hydration heat is closely related to the hydration speed of the cement, this method can effectively reduce the generation rate of hydration heat and avoid cracks and other defects caused by excessive temperature in the concrete.

[0031] In addition, the metakaolin micro-aggregates can store a certain amount of water. During the setting and hardening process of the concrete, as the internal humidity decreases, the water in the micro-aggregates will gradually be released. This slowly released water can provide the necessary conditions for the continuous hydration of the cement, playing a self-curing role.

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

[0033] A preparation method of a concrete reinforcing agent, 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, with the stirring speed controlled at 50-1100 rpm; the stirring is continued for 60-180 minutes. The specific operation is as follows: the prepared metakaolin powder is slowly added to water according to the predetermined proportion, the mechanical stirring device is started and the rotating speed is adjusted. During the stirring process, the changes in the temperature, viscosity and other parameters 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 microgelation process. After the predetermined stirring time, the stirring is stopped and the prepared microgelated metakaolin slurry is sampled for detection. For example, a microscope is used to observe the microstructure integrity of the microgel, a particle size analyzer is used to detect the particle size distribution, and a Zeta potential measuring instrument is used to measure the surface charge characteristics, to ensure that the key indicators of the microgel meet the predetermined technical standards.

[0036] In S1, the SiO2 content of the metakaolin is 45%-55%, the Al2O3 content is 40%-48%, and the activity is 112-128. The above-mentioned ultrafine powder metakaolin has unique physical and chemical properties and can provide a good basis for the subsequent microgelation process.

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

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

[0039] In S2, the temperature of the slurry is controlled at 20-45°C during stirring. At a low stirring speed (such as 50 rpm), the metakaolin particles move slowly in the slurry, the collision frequency is low, the adsorption between particles is weak, and the formed microgel particles are large and less in number. With the stirring speed increased to more than 800 rpm (for example, 1100 rpm), the particles move quickly and collide frequently, the adsorption between particles is enhanced, and the formed microgel particles are small and more in number. The stirring time also has a significant effect on the formation of microgel. When the stirring time is 60 minutes, the microgel begins to form, but the structure is not perfect; when the stirring time is extended to 180 minutes, the microgel structure is more compact and stable, and the particle distribution is more uniform. Temperature has a key influence on the formation of microgel. When the temperature is at a low level of 20°C, the molecular thermal motion is relatively slow, and the chemical reaction rate between metakaolin particles also decreases. This not only slows down the formation speed of microgel, but also makes the structure of the generated microgel not compact enough, the binding force between particles is weak, and finally affects the stability and performance of the microgel.

[0040] With the temperature rising to 45℃, the molecular thermal motion intensifies, the collision frequency and reaction activity between particles significantly improve, which can accelerate the formation speed of microgel and make the microgel structure more compact. However, when the temperature exceeds 45℃, it can cause the water in the slurry to evaporate too quickly, change the rheological properties of the slurry, destroy the dispersion state of kaolin particles, and further affect the uniformity of the microgel, which cannot effectively promote the formation of microgel with microstructure.

[0041] In S2, the magnetic field with a strength not less than 2300 Gauss is formed inside the stirring container to have a significant effect on the trace magnetic components in the kaolin particles during stirring. In the specific operation, the stirring equipment needs to be debugged and the magnetic field needs to be set:

[0042] a. The mechanical stirring equipment is debugged to ensure the stability and controllability of the stirring speed, which can be accurately controlled within the predetermined stirring speed range.

[0043] b. The magnetic field strength measuring instrument is used to ensure that the magnetic field strength inside the stirring container is within 2300-18000 Gauss, and the magnetic field distribution uniformity meets the technical requirements.

[0044] When the kaolin slurry is in this magnetic field environment, the trace magnetic components (such as magnetic impurities of iron and manganese, although the content is small, but enough to be affected by the magnetic field) in the kaolin particles will be affected by the magnetic field force. Although the kaolin particles themselves have weak magnetism, they will also generate magnetic dipole moments under the action of the magnetic field, which will promote the ordered arrangement of the particles along the magnetic field direction. This directional arrangement greatly promotes the contact probability and adsorption effect between particles, further strengthens the microgel effect, and makes the microgel structure more stable and perfect.

[0045] The magnetic field can be arranged as follows: at the bottom of the stirring container, the S and N poles are alternately arranged in a ring shape, so that the magnetic field direction formed at the bottom of the container is perpendicular to the bottom surface and upward or downward; on the side wall of the stirring container, the magnets are arranged in an up-and-down staggered manner, so that the magnetic field direction circulates 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 polarity of the magnetic blocks is arranged in a certain order, so that the magnetic field force continuously acts on the kaolin particles during stirring and guides the ordered movement of the particles. This makes the kaolin particles always subject to stable and effective magnetic field force during the entire stirring process, maximally promotes the ordered arrangement of the trace magnetic components in the particles, and further strengthens the microgel effect.

[0046] The magnet is placed on the stirring rod, which can directly exert a magnetic field force on the surrounding kaolin particles during rotation. When the stirring rod rotates, the magnetic field around it also rotates, exerting a dynamic magnetic field on the particles. This dynamic magnetic field can more effectively promote the rotation and migration of trace magnetic components within the kaolin particles, accelerating the directional arrangement of the particles. Compared to placing magnets only on the walls and bottom of the stirring container, the magnet on the stirring rod can act more closely on the particles, enhancing the effect of the magnetic field on the particles. The particles near the stirring rod will arrange more quickly along the direction of the magnetic field, and under the driving of the stirring rod, the mixing of the particles is more thorough, further improving the contact probability and adsorption effect between the particles, making the microgel structure form faster and more stable and perfect during the stirring process.

[0047] In addition, in order to obtain ultra-high magnetic flux with a smaller volume, the magnets are arranged in a Halbach Array manner, which can greatly enhance the magnetic field on one side to above 18000 Gauss through special S and N pole settings.

[0048] It is worth noting that due to the presence of trace amounts of metal ions and other reasons, the slurry has a certain micro-conductivity. When the stirring rod cuts the magnetic induction lines, it will charge and even generate a micro-current; the charged particles in the slurry have a positive effect on the formation of microgel in the magnetic field. Charged particles in the magnetic field will be affected by the Lorentz force, which will change the trajectory of the particles, making the collision between particles more orderly and frequent. This orderly collision can increase the chances of chemical bonding between particles, helping to form microgel more quickly and uniformly. At the same time, the electrostatic interaction between charged particles can also adjust the dispersion state of the particles, making them more easily aggregate to form stable microgel structures in a magnetic field environment, thereby promoting the formation and growth of microgel and improving the quality and performance of microgel.

[0049] Concrete preparation and performance testing:

[0050] The prepared microgelized metakaolin slurry is added to the ordinary concrete mix in a certain proportion, and test concrete specimens are prepared. At the same time, a group of blank control specimens without microgelized metakaolin slurry are prepared.

[0051] All concrete specimens are subjected to standard curing, and after curing for a specified period (such as 3 days, 7 days, 28 days, 90 days, etc.), the performance indicators such as compressive strength, flexural strength, permeability, and chloride ion resistance are tested. Record and analyze the test data to verify the performance enhancement effect of microgelized metakaolin slurry on concrete.

[0052] It is verified by experiments that the flexural and compressive strengths of the concrete can be increased by more than 30% and even up to 150% in the case of extreme examples under the standard curing conditions after the micro-gelatinized metakaolin slurry is mixed in the concrete at a ratio of 5-15% (relative to the cement dosage).

[0053] For example, when the concrete is prepared by using the general brand P.O42.5 cement (the concrete mixing ratio: cement 1: water 0.49: natural sand 0.92: machine sand 2.76: gravel 4.87: fly ash 20.0%: mineral powder 21.0%: additive 1.9%: micro-gelatinized metakaolin slurry 5%, wherein the ratios of the cement, water, natural sand, machine sand and gravel are mass ratios, and the ratios of the fly ash, mineral powder, additive and micro-gelatinized metakaolin slurry are relative to the cement dosage, which is the conventional preparation expression in the industry), the micro-gelatinized metakaolin slurry is mixed with the cement in the concrete at a ratio of 5:100, and the standard curing method (temperature 20±2℃, relative humidity more than 95%) is used for curing for 3 / 7 / 28 days, and the test results are shown in Table 1. Figs. 1-3 In addition, when the curing time is 56 days, the compressive strength of the sample is compared with that of the sample without the addition of the micro-gelatinized metakaolin slurry, and it is found that the compressive strength of the sample after the addition of the micro-gelatinized metakaolin slurry is increased by more than 80%, and the flexural strength is increased by more than 30%. It can be seen that the micro-gelatinized metakaolin slurry has obvious effect on improving the comprehensive performance of the concrete.

[0054] Although the embodiments of the present application have been disclosed as above, they are not limited to the application listed in the specification and the embodiments, and can be fully applied to various fields suitable for the present application, and other modifications can be easily realized by those skilled in the art, and therefore the present application is not limited to the specific details and the examples shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A concrete reinforcing agent, characterized in that: The concrete reinforcing agent paste contains a large amount of microgels formed by metakaolin particles. After the microgels in the concrete reinforcing agent paste are added to concrete, the microgel structure forms evenly distributed micro-reinforcement points inside the concrete. These micro-reinforcement points fill the tiny pores inside the concrete, reducing the porosity of the concrete and improving the density of the concrete. At the same time, during the concrete setting and hardening process, the microgels interact with the concrete hydration products to form tighter chemical bonds, significantly improving the overall performance of the concrete. The concrete reinforcing agent is in the form of a paste, and the microgel is formed by metakaolin particles and water, and the microgel is in a suspended state in the paste; The preparation method of the concrete reinforcing agent comprises the following steps: S1. Mixing metakaolin and water in a ratio of (0.5-1):1 to form a suitable dispersion of metakaolin particles; S2. Metakaolin and water are added to a high-speed mixing device for mixing. The mixing speed of the concrete enhancer is controlled at 50 to 1100 rpm, and the speed is controlled according to the time period. The mixing is continued for 60 to 180 minutes. 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; The particle size of the metakaolin is 200-2000 mesh.

2. The concrete reinforcing agent according to claim 1, characterized in that In S1, the metakaolin has a SiO2 content of 45%-55%, an Al2O3 content of 40%-48%, and an activity index of 112-128.

3. The concrete reinforcing agent according to claim 1, characterized in that In S2, the initial stirring speed is no more than 100 rpm, and then the stirring speed is gradually increased.

4. The concrete reinforcing agent according to claim 1, characterized in that In S2, the temperature of the slurry is controlled at 20°C-45°C during stirring.

5. The concrete reinforcing agent according to claim 1, characterized in that The magnetic field strength is within a range of 2300 Gauss to 18000 Gauss.

6. The concrete reinforcing agent according to claim 1, characterized in that A strong magnet is provided on the stirring arm of the high-speed stirring device.

7. The concrete reinforcing agent according to claim 6, 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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