Anti-crack concrete
Through the combination of modified hollow microbeads and calcium aluminate powder, the crack problems caused by temperature difference and load of concrete are solved, and the crack resistance and early strength of concrete are improved.
Patent Information
- Application Number
- CN202510478130.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2025-07-18
AI Technical Summary
Concrete is prone to enter water vapor by the sea or in places with abundant rainfall due to small cracks, affecting the stability of the building structure.
The modified hollow microbeads and calcium aluminate powder are used to improve the lipophilicity of the hollow microbeads through organic and inorganic modification treatment, and combined with the early strength enhancement effect of calcium aluminate powder, it reduces temperature difference shrinkage and internal voids, and enhances the crack resistance of concrete.
Effectively inhibit the temperature loss of concrete surface, reduce temperature difference shrinkage cracks, improve early strength and tensile strength, and enhance the overall crack resistance of concrete.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of concrete, and more particularly, to a crack-resistant concrete. Background Art
[0002] Concrete, abbreviated as "concrete", is a general term for engineering composite materials in which aggregates are bonded into a whole by cementitious materials. The term concrete usually refers to cement as a cementitious material, sand and stone as aggregates, and water and other raw materials mixed in a certain proportion and obtained by mixing. Concrete is widely used in civil engineering due to its advantages such as easy availability of raw materials, abundant raw materials and excellent performance.
[0003] In real life, concrete is everywhere, such as roads, bridges, ports, docks, etc. Due to its structural characteristics, concrete has a large number of small cracks inside. When concrete is used at the seaside or in places with heavy rain, a large amount of water vapor often enters the concrete through these cracks, causing the concrete to crack, which in turn affects the building structure and needs to be improved. Summary of the invention
[0004] In order to improve the problem of a large number of small cracks inside concrete, the present application provides a crack-resistant concrete.
[0005] The present application provides a crack-resistant concrete adopting the following technical solution:
[0006] A crack-resistant concrete comprises the following raw materials in parts by weight: 550-750 parts of coarse aggregate, 380-550 parts of fine aggregate, 190-260 parts of cement, 100-130 parts of water, 60-80 parts of modified hollow microspheres and 45-70 parts of fly ash;
[0007] The preparation method of the modified hollow microspheres is as follows: an organic acid modifier and petroleum ether are mixed, the hollow microspheres are added to the petroleum ether containing the organic acid modifier at room temperature, the mass ratio of the hollow microspheres, the organic acid modifier and the petroleum ether is 1:0.5:15, ultrasonic dispersion is performed for 20-30 minutes, stirring, and finally centrifugal separation and drying are performed to obtain the modified hollow microspheres.
[0008] By adopting the above technical scheme, the main components of the hollow microspheres are SiO2 and AL2O3, the surface is coated with a certain thickness of mullite phase and there is a certain amount of hydroxyl group, the surface of the hollow microspheres is modified by an organic acid modifier, so that the surface polarity of the hollow microspheres is reduced, and the surface lipophilicity of the hollow microspheres is improved. After mixing, the modified hollow microspheres are adsorbed on the surface of concrete. Since the hollow microspheres have a hollow structure and a low thermal conductivity, they have good thermal insulation properties, can inhibit the temperature loss of the concrete surface, reduce the temperature difference between the inside and outside of the concrete, thereby reducing the formation of cracks caused by temperature difference shrinkage, and improving the anti-cracking effect of the concrete.
[0009] Preferably, the preparation method of the modified hollow microspheres is as follows: Add hollow microspheres to distilled water at room temperature, with the mass ratio of hollow microspheres to distilled water being 1:15. Ultrasonically disperse for 20 - 30 min, stir, and at this time, the pH meter reading is 8.1. Add Ca(OH)₂ solution and stir, with the pH meter reading being 13.2. Then, keep it in a constant temperature water bath at 50 °C and stir for 60 - 80 min. Intermittently introduce CO₂ at a certain ventilation rate. When the pH meter reading is 8.6, stop introducing CO₂ and continue to stir for 60 - 80 min. Cool to room temperature, filter by suction. After washing the powder with water multiple times, dry it in vacuum for 12 h;
[0010] Mix the organic acid modifier and petroleum ether. Add the dried powder to the petroleum ether containing the organic acid modifier at room temperature. The mass ratio of the dried powder, organic acid modifier, and petroleum ether is 1:0.5:15. Ultrasonically disperse for 20 - 30 min, stir, and finally centrifuge and dry to obtain the modified hollow microspheres.
[0011] By adopting the above technical solution, the mullite phase on the surface of the hollow microspheres has certain chemical inertness, making the surface activity of the hollow microspheres relatively low. The calcium hydroxide system has an excitation effect on the surface of the hollow microspheres. Heating causes Ca(OH)₂ to react with the excited active SiO₂ and Al₂O₃ in a CO₂ environment to generate CaCO₃. CaCO₃ deposits and grows on the surface of the hollow microsphere particles. CaCO₃ has certain activity on the surface of the hollow microsphere particles, making it easier to be adsorbed by the polar groups of the modifier. Therefore, first performing inorganic modification on the surface of the hollow microspheres and then using an organic acid modifier to modify the hollow microspheres can increase the modification amount, further improve the lipophilicity of the surface of the modified hollow microspheres, enable more modified hollow microspheres to adsorb on the concrete surface, improve the heat insulation effect, further reduce the temperature difference inside and outside the concrete, and reduce temperature difference cracks, thereby obtaining a better crack resistance effect.
[0012] Preferably, by weight, the raw materials further include 8 - 12 parts of calcium aluminate powder.
[0013] By adopting the above technical solution, calcium aluminate powder can form calcium aluminate hydrate, and this hydrate can effectively increase the early strength of cement, thereby improving the early strength of concrete. For concrete with high early strength, its tensile strength and stiffness will increase. Under the action of load, the deformation ability of concrete will decrease, and the possibility of crack generation will also be correspondingly reduced. Moreover, the bonding force between concrete particles will be enhanced, reducing the porosity inside the concrete, thereby further reducing the possibility of cracks generated inside the concrete and comprehensively improving the crack resistance performance of concrete.
[0014] Preferably, by weight, the raw materials further include 10 - 15 parts of magnesium oxide.
[0015] By adopting the above technical solution, magnesium oxide reacts with water to form magnesium hydroxide. This process not only generates volume expansion but also absorbs part of the hydration heat, thereby alleviating the temperature rise inside the concrete. This expansion effect helps the concrete structure maintain stability during the cooling process to a certain extent, reduces the generation of cracks, and improves the crack resistance effect of the concrete.
[0016] Preferably, the coarse aggregate includes 25wt%-35wt% of gravel with a particle size of 5mm-15mm and 65wt%-75wt% of gravel with a particle size of 15mm-30mm, and the fine aggregate is river sand with a particle size of 0.5mm-5mm.
[0017] By adopting the above technical solution, the coarse aggregate and the fine aggregate are matched according to the size of the aggregate particle size, so that the strength of the prepared concrete after solidification is greater and the crack resistance performance is stronger.
[0018] Preferably, the organic acid modifier is octadecyl methacrylate.
[0019] In summary, the present application has the following beneficial effects:
[0020] 1. In the present application, the hollow microspheres are surface-modified by an organic acid modifier to improve the surface lipophilicity of the hollow microspheres. After mixing, the modified hollow microspheres are adsorbed on the surface of the concrete. Due to the good heat insulation performance of the hollow microspheres, the heat dissipation on the surface of the concrete can be inhibited, the temperature difference inside and outside the concrete can be reduced, and thus the formation of cracks caused by temperature difference shrinkage can be reduced, and the crack resistance effect of the concrete is improved.
[0021] 2. In the present application, the surface of the hollow microspheres is first inorganically modified and then modified by an organic acid modifier. This can increase the modification amount, further improve the surface lipophilicity of the modified hollow microspheres, enable more modified hollow microspheres to be adsorbed on the surface of the concrete, improve the heat insulation effect, further reduce the temperature difference inside and outside the concrete, and reduce temperature difference cracks, thereby obtaining a better crack resistance effect.
[0022] 3. The present application preferably uses calcium aluminate powder. The calcium aluminate powder can form calcium aluminate hydrate, and this hydrate can effectively increase the early strength of the cement, and then improve the early strength of the concrete, thereby improving the crack resistance performance of the concrete. Detailed Embodiments
[0023] The following further elaborates on the present application with reference to embodiments.
[0024]
[0025]
[0026] Except as otherwise specified, the raw materials used in the following embodiments are all commercially available, and wt% refers to weight percentage.
[0027] Preparation Example of Modified Hollow Microspheres
[0028] Preparation Example 1
[0029] The preparation method of the modified hollow microspheres is as follows: Mix an organic acid modifier and petroleum ether. The organic acid modifier is octadecyl methacrylate. At room temperature, add hollow microspheres to the petroleum ether containing the organic acid modifier. The mass ratio of the hollow microspheres, the organic acid modifier, and petroleum ether is 1:0.5:15. Ultrasonically disperse for 20 - 30 min, stir, and finally perform centrifugal separation and drying to obtain the modified hollow microspheres.
[0030] Preparation Example 2
[0031] The preparation method of the modified hollow microspheres is as follows: At room temperature, add hollow microspheres to distilled water. The mass ratio of the hollow microspheres to distilled water is 1:15. Ultrasonically disperse for 20 - 30 min and stir. At this time, the pH meter reading is 8.1. Add Ca(OH)2 solution and stir. The pH meter reading is 13.2. Then, keep it in a constant temperature water bath at 50 °C and stir for 60 - 80 min. Intermittently introduce CO2 at a certain ventilation rate. When the pH meter reading is 8.6, stop introducing CO2 and continue to stir for 60 - 80 min. Cool to room temperature, perform suction filtration. After washing the powder with water multiple times, vacuum dry for 12 h;
[0032] Mix an organic acid modifier and petroleum ether. The organic acid modifier is octadecyl methacrylate. At room temperature, add the dried powder to the petroleum ether containing the organic acid modifier. The mass ratio of the dried powder, the organic acid modifier, and petroleum ether is 1:0.5:15. Ultrasonically disperse for 20 - 30 min, stir, and finally perform centrifugal separation and drying to obtain the modified hollow microspheres.
[0033] Examples
[0034] Example 1
[0035] This application discloses a crack - resistant concrete, which includes the following raw materials by weight: 550 parts of coarse aggregate, 380 parts of fine aggregate, 190 parts of cement, 100 parts of water, 60 parts of modified hollow microspheres, and 45 parts of fly ash.
[0036] Among them, the coarse aggregate includes 25 wt% of crushed stones with a particle size of 5 mm - 15 mm and 75 wt% of crushed stones with a particle size of 15 mm - 30 mm. The fine aggregate is river sand with a particle size of 0.5 mm - 5 mm. The modified hollow microspheres are prepared from Preparation Example 1.
[0037] Example 2
[0038] The present application discloses a crack-resistant concrete, which comprises the following raw materials by weight: 750 parts of coarse aggregate, 550 parts of fine aggregate, 260 parts of cement, 130 parts of water, 80 parts of modified hollow microspheres and 70 parts of fly ash.
[0039] Among them, the coarse aggregate includes 35 wt% of crushed stones with a particle size of 5 mm - 15 mm and 65 wt% of crushed stones with a particle size of 15 mm - 30 mm. The fine aggregate is river sand with a particle size of 0.5 mm - 5 mm, and the modified hollow microspheres are prepared from Preparation Example 1.
[0040] Example 3
[0041] The present application discloses a crack-resistant concrete, which comprises the following raw materials by weight: 650 parts of coarse aggregate, 460 parts of fine aggregate, 230 parts of cement, 120 parts of water, 70 parts of modified hollow microspheres and 60 parts of fly ash.
[0042] Among them, the coarse aggregate includes 30 wt% of crushed stones with a particle size of 5 mm - 15 mm and 70 wt% of crushed stones with a particle size of 15 mm - 30 mm. The fine aggregate is river sand with a particle size of 0.5 mm - 5 mm, and the modified hollow microspheres are prepared from Preparation Example 1.
[0043] Example 4
[0044] The difference from Example 1 is that the modified hollow microspheres are prepared from Preparation Example 2.
[0045] Example 5
[0046] The difference from Example 1 is that the raw materials further include 8 parts of calcium aluminate powder.
[0047] Example 6
[0048] The difference from Example 1 is that the raw materials further include 10 parts of magnesium oxide.
[0049] Example 7
[0050] The present application discloses a crack-resistant concrete, which comprises the following raw materials by weight: 550 parts of coarse aggregate, 380 parts of fine aggregate, 190 parts of cement, 100 parts of water, 60 parts of modified hollow microspheres, 45 parts of fly ash, 8 parts of calcium aluminate powder and 10 parts of magnesium oxide.
[0051] Among them, the coarse aggregate includes 25 wt% of crushed stones with a particle size of 5 mm - 15 mm and 75 wt% of crushed stones with a particle size of 15 mm - 30 mm. The fine aggregate is river sand with a particle size of 0.5 mm - 5 mm, and the modified hollow microspheres are prepared from Preparation Example 2.
[0052] Example 8
[0053] The present application discloses a crack-resistant concrete, which comprises the following raw materials in parts by weight: 750 parts of coarse aggregate, 550 parts of fine aggregate, 260 parts of cement, 130 parts of water, 80 parts of modified hollow microspheres, 70 parts of fly ash, 12 parts of calcium aluminate powder and 15 parts of magnesium oxide.
[0054] Among them, the coarse aggregate comprises 35 wt% of gravel with a particle size of 5 mm - 15 mm and 65 wt% of gravel with a particle size of 15 mm - 30 mm, the fine aggregate is river sand with a particle size of 0.5 mm - 5 mm, and the modified hollow microspheres are prepared by Preparation Example 2.
[0055] Example 9
[0056] The present application discloses a crack-resistant concrete, which comprises the following raw materials in parts by weight: 650 parts of coarse aggregate, 460 parts of fine aggregate, 230 parts of cement, 120 parts of water, 70 parts of modified hollow microspheres, 60 parts of fly ash, 10 parts of calcium aluminate powder and 13 parts of magnesium oxide.
[0057] Among them, the coarse aggregate comprises 30 wt% of gravel with a particle size of 5 mm - 15 mm and 70 wt% of gravel with a particle size of 15 mm - 30 mm, the fine aggregate is river sand with a particle size of 0.5 mm - 5 mm, and the modified hollow microspheres are prepared by Preparation Example 2.
[0058] Example 10
[0059] The difference from Example 5 is that the calcium aluminate powder is replaced by fly ash.
[0060] Comparative Example
[0061] Comparative Example 1
[0062] The difference from Example 1 is that the concrete without adding modified hollow microspheres in the raw materials is used as the blank control group.
[0063] Comparative Example 2
[0064] The difference from Example 1 is that the modified hollow microspheres are replaced by hollow microspheres.
[0065] Performance Detection Test
[0066] Crack resistance test: The concrete prepared in Examples 1 - 10 and Comparative Examples 1 - 2 was made into concrete blocks with specifications of 150 mm × 150 mm × 150 mm as test specimens. After curing for 28 days, the compressive strength and splitting compressive strength of the test specimens were tested with reference to GB / T 50081 - 2002 "Standard Test Method for Mechanical Properties of Ordinary Concrete". The test results are shown in Table 1 below.
[0067] Table 1 Test Result Table of Each Example and Comparative Example
[0068]
[0069]
[0070] In summary:
[0071] 1. By combining Example 1 and Comparative Examples 1-2 and referring to Table 1, it can be seen that adding modified hollow microspheres to concrete can improve the crack resistance of concrete. The reason may be that: through surface modification of hollow microspheres with an organic acid modifier, the surface polarity of hollow microspheres is reduced, the surface lipophilicity of hollow microspheres is improved, and the modified hollow microspheres are adsorbed on the concrete surface after mixing. Due to the good heat insulation performance of hollow microspheres, the temperature dissipation on the concrete surface can be inhibited, the temperature difference between the inside and outside of the concrete can be reduced, and thus the formation of cracks caused by temperature difference shrinkage can be reduced, improving the crack resistance effect of concrete.
[0072] 2. By combining Examples 1 and 4, it can be seen that first performing inorganic modification on the surface of hollow microspheres and then using an organic acid modifier to modify the hollow microspheres can further improve the crack resistance of concrete. The reason may be that: the mullite phase on the surface of hollow microspheres has certain chemical inertness, making the surface activity of hollow microspheres relatively low. The calcium hydroxide system has an excitation effect on the surface of hollow microspheres. Heating causes Ca(OH)2 to react with the excited active SiO2 and Al2O3 in a CO2 environment to form CaCO3. CaCO3 deposits and grows on the surface of hollow microsphere particles. CaCO3 has certain activity on the surface of hollow microsphere particles, making it easier to be adsorbed by the polar groups of the modifier. Therefore, first performing inorganic modification on the surface of hollow microspheres and then using an organic acid modifier to modify the hollow microspheres can increase the modification amount, further improve the surface lipophilicity of modified hollow microspheres, make more modified hollow microspheres adsorbed on the concrete surface, improve the heat insulation effect, further reduce the temperature difference between the inside and outside of the concrete, reduce temperature difference cracks, and thus obtain a better crack resistance effect.
[0073] 3. By combining Examples 1, 5, and 10, it can be seen that adding calcium aluminate powder to concrete can improve the crack resistance of concrete. The reason may be that: calcium aluminate powder can form calcium aluminate hydrate, and this hydrate can effectively increase the early strength of cement, thereby improving the early strength of concrete. For concrete with high early strength, its tensile strength and stiffness will be improved, the deformation ability of concrete under load will be reduced, the possibility of crack generation will also be correspondingly reduced, and the bonding force between concrete particles will be enhanced, reducing the porosity inside the concrete, thereby further reducing the possibility of cracks generated inside the concrete and comprehensively improving the crack resistance of concrete.
[0074] 4. It can be seen from Examples 1 and 6 that adding magnesium oxide to concrete can improve the crack resistance of concrete. The reason may be that magnesium oxide reacts with water to form magnesium hydroxide. This process not only produces volume expansion but also can absorb part of the hydration heat, thus alleviating the temperature rise inside the concrete. This expansion effect helps the concrete structure maintain stability to a certain extent during the cooling process, reduces the generation of cracks, and improves the crack resistance effect of the concrete.
[0075] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions according to needs, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.
Claims
1. An anti-cracking concrete, characterized in that, It comprises raw materials in the following parts by weight: 550 - 750 parts of coarse aggregate, 380 - 550 parts of fine aggregate, 190 - 260 parts of cement, 100 - 130 parts of water, 60 - 80 parts of modified hollow microspheres, and 45 - 70 parts of fly ash; The preparation method of the modified hollow microspheres is as follows: Mix an organic acid modifier and petroleum ether, and add the hollow microspheres to the petroleum ether containing the organic acid modifier at room temperature. The mass ratio of the hollow microspheres, the organic acid modifier, and petroleum ether is 1:0.5:
15. Ultrasonically disperse for 20 - 30 min, stir, and finally centrifuge and dry to obtain the modified hollow microspheres.
2. The crack-resistant concrete according to claim 1, wherein: The preparation method of the modified hollow microspheres is as follows: Add the hollow microspheres to distilled water at room temperature. The mass ratio of the hollow microspheres to distilled water is 1:
15. Ultrasonically disperse for 20 - 30 min and stir. At this time, the pH meter reading is 8.
1. Add a Ca(OH)2 solution and stir. The pH meter reading is 13.
2. Then keep it in a constant temperature water bath at 50 °C and stir for 60 - 80 min. Intermittently introduce CO2 at a certain ventilation rate. When the pH meter reading is 8.6, stop introducing CO2 and continue to stir for 60 - 80 min. Cool to room temperature, filter by suction. After washing the powder with water multiple times, vacuum dry for 12 h; Mix the organic acid modifier and petroleum ether, and add the dried powder to the petroleum ether containing the organic acid modifier at room temperature. The mass ratio of the dried powder, the organic acid modifier, and petroleum ether is 1:0.5:
15. Ultrasonically disperse for 20 - 30 min, stir, and finally centrifuge and dry to obtain the modified hollow microspheres.
3. The crack-resistant concrete according to claim 1, wherein: By weight, the raw materials further include 8 - 12 parts of calcium aluminate powder.
4. The crack-resistant concrete according to claim 1, characterized in that: By weight, the raw materials further include 10 - 15 parts of magnesium oxide.
5. The crack-resistant concrete according to claim 1, wherein: The coarse aggregate includes 25wt% - 35wt% of gravel with a particle size of 5 mm - 15 mm and 65wt% - 75wt% of gravel with a particle size of 15 mm - 30 mm. The fine aggregate is river sand with a particle size of 0.5 mm - 5 mm.
6. The crack-resistant concrete according to claim 1, wherein: The organic acid modifier is octadecyl methacrylate.