Low-magnetism concrete

Abstract

The invention relates to the technical field of concrete, in particular to low-magnetism concrete. The low-magnetism concrete is prepared from the following raw materials: Portland cement, ash, fine aggregate, aluminum oxide modified coarse aggregate, an additive, graphene oxide modified basalt fiber and water, wherein the particle size of the fine aggregate comprises the following components in percentage by weight: 20%-50% of the particle size of 1-3mm, 20%-50% of the particle size of 3-5.5 mm and 0%-60% of the particle size of 5.5-10mm; the additive is obtained by compounding a water reducing agent and sodium gluconate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete, in particular to a low magnetic concrete. BACKGROUND

[0002] Low magnetic concrete is a kind of special concrete which significantly reduces magnetic permeability and residual magnetism through material modification, and plays a crucial role in the fields of astronomical observation, precision measurement, medical facilities, geological exploration and national defense science and technology development; but there are few studies on low magnetic concrete at present.

[0003] The related prior art prepares a low magnetic concrete by selecting and proportioning specific raw materials such as low magnetic cement and admixtures, combined with non-magnetic mixing blades; but it has strict requirements for the selection of raw materials, and due to the unstable magnetism of the raw materials, it is easy to cause the magneticity of the concrete to exceed the standard, so that a stable low magnetic environment cannot be realized. In addition, the low magnetic performance of the concrete often needs to sacrifice part of the mechanical properties.

[0004] Therefore, it is urgent to provide a low magnetic concrete with excellent comprehensive performance to meet market demand. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a low magnetic concrete which has low magnetic performance, with the magnetic field value at 5cm after magnetization controlled to be ≤40nT, the magnetic field value at 15cm after magnetization controlled to be ≤10nT, and the magnetic field value at 30cm after magnetization controlled to be ≤3nT; it also has excellent compressive strength (≥65MPa), flexural strength (≥9Mpa) and splitting tensile strength (≥6Mpa), and can be used as a building or pavement material in the fields of astronomical observation, precision measurement, medical facilities, geological exploration and national defense science and technology development.

[0006] The present application also proposes a preparation method of the low magnetic concrete.

[0007] The present application also proposes an application of the low magnetic concrete in preparing a building or pavement material.

[0008] In the first aspect of the present application, a low magnetic concrete is provided, and the preparation raw materials of the low magnetic concrete include the following components:

[0009] portland cement, ash, fine aggregate, alumina modified coarse aggregate, admixture, graphene oxide modified basalt fiber and water;

[0010] The particle size of the fine aggregate includes the following particle size by weight percentage: 1-3mm 20-50%, 3-5.5mm 20-50%, 5.5-10mm 0-60%;

[0011] The additive is compounded by a water reducing agent and sodium gluconate.

[0012] The low-magnetic concrete according to the embodiment of the application has at least the following beneficial effects:

[0013] The coating of alumina can introduce a non-magnetic insulating layer to reduce the magnetic permeability of the concrete. The application selects alumina to modify the coarse aggregate instead of adding nano-alumina, because the added nano-alumina is easy to cause agglomeration, which is not conducive to the insulating effect and the mechanical properties of the concrete. The modification of the coarse aggregate can greatly improve the agglomeration of the nano-alumina and improve the uniformity of the distribution, because the dispersion performance of the coarse aggregate is good. The alumina modified coarse aggregate has a large particle size range, resulting in a large gap and uneven internal quality. Therefore, the application adopts fine aggregate with different particle sizes to fully fill the gap of the alumina modified coarse aggregate, which significantly enhances the mechanical properties of the concrete.

[0014] The application selects basalt fibers, which have strong toughness and low magnetism, so that the crack resistance can be improved while avoiding the magnetic interference caused by traditional steel fibers. Further, the graphene oxide modified basalt fibers are uniformly distributed in the concrete. The graphene oxide can interfere with the magnetic field conduction by forming a barrier. At the same time, the conductive network of the graphene oxide can dissipate the external alternating magnetic field energy through the eddy current effect, thereby reducing the overall magnetic permeability. In addition, the alumina-graphene oxide heterostructure can produce a local electromagnetic field offset effect to further reduce the magnetism of the concrete.

[0015] The additive of the application is compounded by a water reducing agent and sodium gluconate, which can adjust the setting time, improve the construction performance, and improve the dispersity of the raw materials during the construction process, thereby improving the mechanical properties and durability of the concrete.

[0016] In some embodiments of the application, the Portland cement is selected from at least one of P.II 42.5 Portland cement, P.O 42.5R ordinary Portland cement, P.W 42.5 white Portland cement, and P.W 52.5 white Portland cement.

[0017] In some embodiments of the application, the ash material includes at least one selected from silica fume, metakaolin, and slag powder, and fly ash; preferably, the ash material includes silica fume and fly ash; more preferably, the mass ratio of the at least one selected from silica fume, metakaolin, and slag powder, and fly ash is 1:2-6, for example, 1:2-4, 1:2-3, or 1:2.5-4.

[0018] The filling and pozzolanic effect of silica ash make it an effective additional cementitious material, which can enhance the physical and mechanical properties of concrete, improve the bleeding and cohesiveness of fresh concrete, increase the strength of concrete, and improve the impermeability, abrasion resistance, and air-erosion resistance of concrete. When silica ash is added to cement concrete, the SiO2 in the silica ash and the hydration product Ca(OH)2 of cement rapidly undergo secondary hydration reaction to generate hydrated calcium silicate gel, which can make the cement stone dense. Fly ash contains a large amount of SiO2 and Al2O3, which are active oxides. When the fly ash is added to cement, it can undergo secondary reaction with the hydration product Ca(OH)2 to generate stable hydrated calcium silicate gel, which has obvious strengthening effect. In addition, like water reducing agents, fly ash also has a certain water reducing effect. For example, the particles of grade fly ash are fine, which can be uniformly distributed in concrete, so that the total porosity of the cement stone is reduced, the hardened concrete is more dense, and the strength of the concrete is also improved.

[0019] In some embodiments of the present application, the fly ash is selected from at least one of grade I, grade II, grade III, ultra-fine F-class or C-class fly ash.

[0020] In some embodiments of the present application, the fly ash accounts for 2wt% to 10wt% of the preparation raw materials, for example, 2wt% to 9wt%, 2wt% to 8wt%, 2wt% to 7wt%, 2wt% to 6wt%, 2wt% to 5wt%, 2wt% to 4wt%, 2wt% to 3wt%, 3wt% to 9wt%, 3wt% to 8wt%, 3wt% to 7wt%, 3wt% to 6wt%, 3wt% to 5wt%, 3wt% to 4wt%.

[0021] In some embodiments of the present application, the fine aggregate is selected from at least one of river sand, quartz sand, and machine-made sand.

[0022] In some embodiments of the present application, the particle size of the fine aggregate, by weight percentage, includes the following particle size: 1-3mm 20%-40%, 3-5.5mm 20%-40%, and 5.5-10mm 20%-60%; preferably, includes the following particle size: 1-3mm 30%-40%, 3-5.5mm 30%-40%, and 5.5-10mm 20%-40%.

[0023] In some embodiments of the present application, the coarse aggregate in the alumina-modified coarse aggregate is selected from at least one of quartzite, granite, and basalt.

[0024] In some embodiments of the present application, the particle size of the coarse aggregate in the alumina-modified coarse aggregate is 10-20mm.

[0025] In some embodiments of the present application, the alumina-modified coarse aggregate is obtained by stirring, drying and sintering the coarse aggregate with an aluminum salt solution.

[0026] In some embodiments of the present application, the method for preparing the alumina-modified coarse aggregate specifically comprises the following steps:

[0027] S1, adding a first aluminum salt solution to the coarse aggregate, stirring for 2-5 hours, and then drying at 100-120°C;

[0028] S2, adding a second aluminum salt solution to the dried sample of step S1, stirring for 2-5 hours, filtering, washing with water, and then drying at 100-120°C, and finally sintering at 500-750°C for 0.5-2 hours.

[0029] Preferably, the first aluminum salt solution and the second aluminum salt solution are both aluminum chloride solutions.

[0030] Preferably, in step S1, the concentration of the first aluminum chloride solution is 1-2 mol / L, and the mass-volume ratio of the coarse aggregate to the first aluminum chloride solution is 1:(4-5) g / mL.

[0031] Preferably, in step S2, the concentration of the second aluminum chloride solution is 0.5-1 mol / L, and the mass-volume ratio of the dried sample to the second aluminum chloride solution is 1:(1-3) g / mL.

[0032] In some embodiments of the present application, the length of the basalt fiber in the graphene oxide-modified basalt fiber is 3-10 mm, for example, 3-8 mm, 3-5 mm, 4-8 mm, and / or the diameter is 5-15 μm, for example, 5-12 μm, 5-10 μm, 6-12 μm, 6-10 μm, 7-9 μm.

[0033] In some embodiments of the present application, the graphene oxide-modified basalt fiber is obtained by grafting graphene oxide onto the surface of the basalt fiber under the action of a coupling agent.

[0034] In some embodiments of the present application, the method for preparing the graphene oxide-modified basalt fiber specifically comprises the following steps:

[0035] In a solvent, adding a coupling agent and basalt fiber, drying after reaction, to obtain pretreated basalt fiber; then adding an aqueous solution of graphene oxide, adjusting the pH to 2-4, and reacting at 75-85°C, and then washing and drying.

[0036] In some embodiments of the present application, the solvent is a 50-75% ethanol solution.

[0037] In some embodiments of the present application, the mass ratio of the coupling agent to the basalt fiber is 1:2-5.

[0038] In some embodiments of the present application, the reaction time is 2-4h.

[0039] In some embodiments of the present application, the drying temperature is 80-120℃.

[0040] In some embodiments of the present application, the concentration of the aqueous solution of graphene oxide is 0.5-2g / L.

[0041] In some embodiments of the present application, the mass of the pretreated basalt fiber to the volume of the aqueous solution of graphene oxide is 10-30g / L.

[0042] In some embodiments of the present application, the mass ratio of the water reducing agent to sodium gluconate is 1-6:1, for example, 1-4:1, 1-3:1, 1-2.5:1, 1-2:1.

[0043] In some embodiments of the present application, the water reducing agent is selected from at least one of polycarboxylic acid type water reducing agent, naphthalene type water reducing agent, anthracene type water reducing agent, aminosulfonate type water reducing agent, and lignin sulfonate type water reducing agent; preferably, the water reducing agent is polycarboxylic acid type water reducing agent.

[0044] In some embodiments of the present application, the preparation raw materials of the low-magnetic concrete include the following components in terms of weight fraction:

[0045]

[0046]

[0047] In some preferred embodiments of the present application, the preparation raw materials of the low-magnetic concrete include the following components in terms of weight fraction:

[0048]

[0049] In the second aspect of the present application, a method for preparing the low-magnetic concrete is provided, which comprises mixing the preparation raw materials to obtain the low-magnetic concrete.

[0050] According to the preparation method of the embodiments of the present application, at least the following beneficial effects are achieved:

[0051] The preparation method of the low-magnetic concrete of the present application is simple and suitable for industrial production.

[0052] In some embodiments of the present application, the preparation method specifically comprises the following steps:

[0053] S1, according to the weight parts, the Portland cement, ash and graphene oxide modified basalt fiber are mixed, then the admixture and 50%-90% water are added and mixed to obtain a primary mixture;

[0054] S2, the fine aggregate, the alumina modified coarse aggregate and the remaining 10%-50% water are mixed and added into the primary mixture, and then stirred uniformly.

[0055] In a third aspect, the application provides the use of the low-magnetic concrete in preparing building or pavement materials.

[0056] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. DETAILED DESCRIPTION

[0057] The concept and the technical effects of the present application will be described in detail below in combination with the embodiments, so as to fully understand the purposes, features and effects of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0058] The words "preferably", "more preferably" and the like in the present application mean the embodiments of the present application which can provide certain beneficial effects in certain cases. However, in the same or other cases, other embodiments can also be preferred. In addition, the description of one or more preferred embodiments does not mean that other embodiments are not available, nor is it intended to exclude other embodiments from the scope of the present application.

[0059] When a numerical range is disclosed herein, the above range is considered to be continuous, and includes the minimum value and the maximum value of the range, and every value between the minimum value and the maximum value. Further, when the range refers to an integer, every integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges incorporated therein.

[0060] In the description of the present application, the reference term "and / or" includes all and any combinations of one or more related listed items.

[0061] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0062] In the description of the present application, "about" means that the allowable error is within ±10%, and further, within ±5%.

[0063] Unless otherwise noted, the specific conditions in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be purchased on the market.

[0064] Example 1

[0065] The present embodiment provides a low-magnetic concrete and a preparation method thereof. The preparation raw material of the low-magnetic concrete is the following components according to the weight fraction:

[0066]

[0067] The P.W42.5 white cement is purchased from Albortland (Anqing) Co., Ltd., and the whiteness is 89%.

[0068] The fly ash is grade II fly ash purchased from Hebei Kexu Building Material Co., Ltd., and the specific surface area is about 300 m 2 / kg.

[0069] The silica ash is purchased from Shifeng Mining Processing Factory in Lingshou County, and the SiO2 content is about 98 wt%, and the specific surface area is about 18000 m 2 / kg.

[0070] The natural river sand includes the following different particle size aggregates, and the weight percentage is: 1-3 mm 30%-40%, 3-5.5 mm 30%-40%, 5.5-10 mm 20%-40%.

[0071] The alumina modified quartzite is prepared by the following steps:

[0072] Take 100 parts of dry quartzite coarse aggregate (particle size about 13-18 mm), add 1.5 mol / L AlCl3 solution according to the mass liquid ratio of 1:4 g / mL, stir for 4 h, and then dry at 100℃. Take the dried sample, add 1 mol / L AlCl3 solution according to the mass liquid ratio of 1:3 g / mL, stir for 4 h, wash with water after filtration, dry at 100℃, and finally sinter at 600℃ for 1 h to obtain alumina modified quartzite.

[0073] The polycarboxylic acid type water reducing agent is purchased from Guangdong Ruian Science and Technology Industrial Co., Ltd., and the solid content is about 20%.

[0074] The graphene oxide modified basalt fiber is prepared by the following steps:

[0075] Mix KH550 with an ethanol solution with a volume concentration of 70%, hydrolyze for 2 h, and prepare a KH550 solution with a content of 1.5%. Then add basalt fiber (Shandong Taicheng Fiber Co., Ltd., length about 5 mm, diameter about 8 μm) to the KH550 solution according to a proportion of 50 g / L, take out after stirring for 3 h, and dry in an 80℃ oven to prepare pretreated basalt fiber. Take GO, ultrasonically disperse for 1 h to prepare a graphene oxide solution with a concentration of 1.0 g / L, then add pretreated basalt fiber according to a proportion of 20 g / L, adjust the pH to 3 with concentrated hydrochloric acid, and perform water bath at 80℃ for 2 h. Wash the product with water, and then dry at 120℃ for 12 h to prepare graphene oxide modified basalt fiber.

[0076] Sodium gluconate is purchased from Suzhou Boguier Chemical Technology Co., Ltd.

[0077] The preparation method of the low-magnetic concrete of the present embodiment comprises:

[0078] According to the above weight fraction, first mix P.W42.5 white cement, fly ash, silica fume, and 50% graphene oxide modified basalt fiber, then add the remaining 50% graphene oxide modified basalt fiber, sodium gluconate, polycarboxylic acid type water reducing agent, and 80% water, mix to obtain a preliminary mixture; then mix fine aggregate, alumina modified coarse aggregate, and the remaining 20% water, and pour into the preliminary mixture, and stir uniformly to discharge.

[0079] Example 2

[0080] The present embodiment provides a low-magnetic concrete and a preparation method thereof, which are prepared according to the method in Example 1, and the only difference is that the preparation raw materials of the low-magnetic concrete comprise the following components according to the weight fraction:

[0081]

[0082] Example 3

[0083] This example provides a low magnetic concrete and a method for preparing the same, which is carried out according to Example 1, with the difference that the raw materials for preparing the low magnetic concrete comprise the following components, by weight fraction:

[0084]

[0085] Example 4

[0086] This example provides a low magnetic concrete and a method for preparing the same, which is carried out according to Example 1, with the difference that the raw materials for preparing the low magnetic concrete comprise the following components, by weight fraction:

[0087]

[0088] Example 5

[0089] This example provides a low magnetic concrete and a method for preparing the same, which is carried out according to Example 1, with the difference that the raw materials for preparing the low magnetic concrete comprise the following components, by weight fraction:

[0090]

[0091] Comparative Example 1

[0092] This comparative example provides a low magnetic concrete and a method for preparing the same, which is carried out according to Example 3, with the difference that the raw materials for preparing the low magnetic concrete comprise the following components, by weight fraction:

[0093]

[0094] Comparative Example 2

[0095] This comparative example provides a low magnetic concrete and a method for preparing the same, which is carried out according to Comparative Example 1, with the difference that the graphene oxide modified basalt fiber is replaced by steel fiber, i.e. the raw materials for preparing the low magnetic concrete comprise the following components, by weight fraction:

[0096]

[0097] Comparative Example 3

[0098] This comparative example provides a low magnetic concrete and a method for preparing the same, which is carried out according to Example 1, with the difference that the particle size of the fine aggregate is 1-3 mm.

[0099] Comparative Example 4

[0100] This comparative example provides a low magnetic concrete and a method for preparing the same, which is carried out according to Example 1, with the difference that it does not contain sodium gluconate, i.e. the raw materials for preparing the low magnetic concrete comprise the following components, by weight fraction:

[0101]

[0102]

[0103] Test Example 1: Mechanical property test

[0104] The concrete slurries obtained in Examples 1-5 and Comparative Examples 1-4 above were cast in molds (100 mm x 100 mm x 100 mm) to form concrete specimens, and the molds were removed after 24 hours. The obtained specimens were transferred to a curing room for standard curing for 28 days to obtain concrete test pieces A. Concrete test pieces B were prepared in the same manner using molds (150 mm x 150 mm x 600 mm).

[0105] The compressive strength, splitting tensile strength and flexural strength of the concrete of Examples 1-5 and Comparative Examples 1-4 above were tested according to the method described in the Standard Test Method for Mechanical Properties of Ordinary Concrete, and the results are shown in Table 1.

[0106] Table 1: Results of mechanical property test

[0107] Compressive strength (Mpa) Flexural strength (Mpa) Split tensile strength (Mpa) Example 1 70.8 10.4 7.2 Example 2 69.8 9.7 6.8 Example 3 70.1 10.8 7.3 Example 4 68.1 10.1 6.4 Example 5 70.2 10.5 7.2 Comparative Example 1 62.4 8.3 5.6 Comparative Example 2 66.7 8.8 5.2 Comparative Example 3 57.9 7.8 4.9 Comparative Example 4 60.5 8.3 5.4

[0108] As shown in Table 1, the concrete obtained in Examples 1-5 has excellent compressive strength, flexural strength and splitting tensile strength, while the mechanical properties of the concrete obtained in Comparative Examples 3 and 4 are significantly lower than those of Examples 1-5.

[0109] Test Example 2: Magnetic property test

[0110] According to the existing test method, the magnetic properties of the concrete of the above examples and comparative examples were tested as follows. A magnetometer was connected to a probe and fixed to the edge of a workbench so that the center point of the probe was fixed at the same height as the middle of the test piece or standard container. The verticality was adjusted. Three distances of 5 cm, 15 cm and 30 cm from the outer surface of the probe were measured on the workbench surface, and a straight line was drawn as a measurement distance mark. The power switch was turned on, and the probe was preheated for 5 minutes and adjusted to zero. The test piece or container was placed in the magnetizing device for magnetization without changing the direction and posture, and the magnetization time was 3 minutes. The test piece or container was accurately placed on the measurement mark, and the magnetic field values at different distances were measured in sequence. The results of the magnetic property test are shown in Table 2.

[0111] Table 2: Results of magnetic property test

[0112]

[0113] As is apparent from the results of Table 2, the concrete produced in Examples 1 to 4 has excellent low magnetic properties and can effectively prevent magnetic interference. Example 5, which has similar raw materials to Examples 1 to 4, is expected to have excellent low magnetic properties as well.

[0114] The above detailed description has been made for the embodiments of the present application, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present application. Furthermore, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A low magnetic concrete, characterized in that: The raw materials for preparation include the following components: Portland cement, ash, fine aggregate, alumina modified coarse aggregate, admixtures, graphene oxide modified basalt fiber and water; The particle size of the fine aggregate, by weight percentage, includes the following particle sizes: 1-3 mm 20%-50%, 3-5.5 mm 20%-50%, 5.5-10 mm 0%-60%; The admixture is obtained by compounding a water reducing agent and sodium gluconate.

2. The low magnetic concrete according to claim 1, characterized in that The silicate cement is selected from at least one of P.II42.5 silicate cement, P.O42.5R ordinary silicate cement, P.W42.5 white silicate cement, and P.W52.5 white silicate cement.

3. The low magnetic concrete according to claim 1, characterized in that The ash material includes at least one selected from silica fume, metakaolin, slag powder and fly ash; The fly ash accounts for 2 wt% to 10 wt% of the raw materials.

4. The low magnetic concrete according to claim 1, characterized in that The fine aggregate is selected from at least one of river sand, quartz sand and machine-made sand; The coarse aggregate in the alumina modified coarse aggregate is selected from at least one of quartzite, granite and basalt.

5. The low magnetic concrete according to claim 1, characterized in that The alumina modified coarse aggregate is obtained by mixing coarse aggregate with aluminum salt solution, drying and sintering; The particle size of the coarse aggregate in the alumina modified coarse aggregate is 10 to 20 mm.

6. The low magnetic concrete according to claim 1, characterized in that The graphene oxide modified basalt fiber is obtained by grafting graphene oxide onto the surface of the basalt fiber under the action of a coupling agent.

7. The low magnetic concrete according to claim 1, characterized in that The mass ratio of the water reducer to sodium gluconate is 1 to 6:

1.

8. The low magnetic concrete according to any one of claims 1 to 7, characterized in that The raw materials for preparation include the following components in parts by weight:

9. A method for preparing low magnetic concrete according to any one of claims 1 to 8, characterized in that: The method comprises mixing the above-mentioned raw materials.

10. Use of the low magnetic concrete according to any one of claims 1 to 8 in preparing building or pavement materials.

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