High-strength low-heat-conductivity self-compacting concrete and preparation method thereof

Abstract

The invention relates to the technical field of concrete, and particularly discloses high-strength low-heat-conductivity self-compacting concrete and a preparation method thereof. The high-strength low-heat-conductivity self-compacting concrete can maintain ideal strength performance while improving the heat insulation performance, so that the high-strength low-heat-conductivity self-compacting concrete is more suitable for being applied to occasions sensitive to temperature, such as underground spaces and external walls in severe cold areas. In addition, the ceramsite provided by the invention also provides a new consumption way for the vanadium slag, and can effectively realize recycling of wastes.

Description

Technical Field

[0001] This application relates to the technical field of concrete, and more specifically, it relates to a high-strength and low-thermal-conductivity self-compacting concrete and its preparation method. Background Art

[0002] With the development of social economy and the acceleration of urbanization, people have put forward higher requirements for the functionality and aesthetics of buildings. Traditional concrete has been restricted in the application of modern construction projects due to its limited strength and relatively high thermal conductivity. In recent years, researchers have been committed to developing new types of high-performance concrete to meet these needs. Among them, self-compacting concrete has received extensive attention due to its good fluidity and filling properties. However, existing self-compacting concrete often neglects the research and optimization of its thermal conductivity.

[0003] Currently, the main technical means to improve the heat insulation performance of concrete include adding lightweight aggregates or foaming agents. For example, foam concrete forms closed pores by incorporating foaming agents. Although this means can significantly reduce the thermal conductivity, its compressive strength will also be greatly affected, making it difficult to meet the requirements of load-bearing structures. Autoclaved aerated concrete has the characteristics of light weight and low thermal conductivity, but its surface strength is low, it is easy to be damaged, and its waterproof performance is poor, requiring additional strengthening and protective layer treatment.

[0004] Regarding the above-mentioned related technologies, the inventor believes that although the current means can reduce the thermal conductivity of concrete to a certain extent, it is often difficult to maintain its mechanical properties while reducing the thermal conductivity. Especially in some temperature-sensitive application scenarios (such as underground spaces, exterior walls in cold regions), traditional concrete is difficult to meet the requirements of both mechanical properties and thermal performance at the same time. Summary of the Invention

[0005] In related technologies, it is often difficult to maintain the mechanical properties of concrete while reducing its thermal conductivity, which limits the application of concrete in scenarios such as underground spaces and exterior walls in cold regions. To improve this defect, this application provides a high-strength and low-thermal-conductivity self-compacting concrete and its preparation method.

[0006] In the first aspect, this application provides a high-strength and low-thermal-conductivity self-compacting concrete, adopting the following technical solution: A high-strength and low-thermal-conductivity self-compacting concrete, comprising the following components in parts by weight: 330 - 355 parts of cement, 125 - 135 parts of mineral admixture, 25 - 30 parts of glass microspheres, 380 - 420 parts of fine aggregate, 500 - 520 parts of coarse aggregate, 115 - 125 parts of water, 10 - 12 parts of water reducer, 25 - 30 parts of shrinkage-reducing agent, 28 - 35 parts of ceramic fiber; the fine aggregate includes light sand, the coarse aggregate includes ceramsite, steel slag and porous basalt gravel, the ceramsite is calcined from green balls, and the green balls contain 55 - 60wt% of vanadium slag.

[0007] By adopting the above technical solutions, the application optimizes the raw material ratio of concrete, realizes the self-compaction of the concrete mixture, and further optimizes the raw material types on this basis. Among the raw materials selected in the application, aggregates such as light sand, ceramsite, steel slag, and porous basalt gravel all have a porous structure, and can hinder the transfer of heat through the air sealed in the pores. The sizes of the light sand and ceramic fiber are relatively small, and can fill the voids between the coarse aggregates such as ceramsite, steel slag, and porous basalt gravel, thereby jointly dividing the heat conduction path. At the same time, the ceramic fiber itself has a low thermal conductivity and can produce a synergistic heat insulation effect with the above-mentioned coarse and fine aggregates. The main component of the ceramsite in the application is vanadium slag, and an enamel layer will be formed on the surface after calcination, making the ceramsite have a high strength. The ceramic fiber can prevent the formation and expansion of microcracks inside the concrete. Coupled with the fact that the steel slag and porous basalt gravel themselves have a high strength, the enhancement of the concrete is realized synergistically. The high-strength and low-thermal-conductivity self-compacting concrete of the application can maintain an ideal strength performance while improving the heat insulation performance, and is thus more suitable for applications in temperature-sensitive occasions such as underground spaces and exterior walls in cold regions. In addition, the ceramsite in the application also provides a new consumption way for vanadium slag, and can effectively realize the recycling of waste.

[0008] Preferably, the ceramsite is prepared according to the following method: (1) Mix vanadium slag, clay, calcium carbonate, and fly ash, grind the mixture, then add water and roll it into balls, and dry to obtain green balls for standby; (2) Transfer the green balls to a sintering furnace for preheating. After the preheating is completed, continue heating to the sintering temperature, naturally cool after heat preservation calcination, and obtain ceramsite.

[0009] By adopting the above technical solutions, while using vanadium slag as the main raw material of the ceramsite, the application also adds clay as a binder, uses fly ash as an aluminum source to adjust the silicon-aluminum ratio, and uses calcium carbonate as a pore-forming agent. During the calcination process, mineral phases such as quartz, plagioclase, and albite are formed inside the ceramsite, and the calcium oxide generated after the decomposition of calcium carbonate can react with quartz to produce wollastonite, and wollastonite can cooperate with other mineral phases synergistically, which helps to fully improve the strength of the ceramsite.

[0010] Preferably, in step (1) of preparing the ceramsite, glass powder is also mixed with vanadium slag, clay, calcium carbonate, and fly ash.

[0011] By adopting the above technical solutions, the sodium oxide in the glass powder has a fluxing effect, promoting the combination between the raw material powders, and the addition of the glass powder also makes the ceramsite contain more glass bodies, thus being able to improve the mechanical properties of the ceramsite and helping to maintain a high strength while improving the heat insulation performance of the concrete.

[0012] Preferably, in step (2) of preparing the ceramsite, the calcination temperature is 1130 - 1170 °C.

[0013] By adopting the above technical solution, the present application optimizes the calcination temperature of the ceramsite, which can provide favorable conditions for the reaction between various raw materials, improve the mechanical properties of the ceramsite, and help maintain a relatively high strength while improving the heat insulation performance of the concrete.

[0014] Preferably, in step (2) of preparing the ceramsite, the calcination time is 20 - 30 min.

[0015] By adopting the above technical solution, the present application optimizes the calcination time of the ceramsite, which helps the full reaction between various raw materials.

[0016] Preferably, the light sand includes at least one of aerated concrete crushed materials and power plant bottom slag.

[0017] By adopting the above technical solution, the present application uses aerated concrete crushed materials and power plant bottom slag as light sand, realizes the recycling of waste, and can make full use of the advantages of the low thermal conductivity of aerated concrete and power plant bottom slag, which helps to improve the heat insulation performance of the concrete.

[0018] Preferably, the mineral admixture includes class F grade I fly ash.

[0019] By adopting the above technical solution, the present application optimizes class F grade I fly ash as the mineral admixture. Class F grade I fly ash has relatively high reactivity, which helps to improve the strength performance of the concrete.

[0020] Preferably, the mineral admixture includes bentonite, and the weight of the bentonite accounts for 25 - 30% of the total weight of the mineral admixture.

[0021] By adopting the above technical solution, the present application optimizes bentonite as the mineral admixture and optimizes the dosage range of bentonite. By using the water absorption - water release characteristics of bentonite, the workability of the mortar is improved, the hydration of cement is made more sufficient, and thus the heat insulation performance and mechanical properties of the concrete are improved.

[0022] Preferably, the mineral admixture further includes metakaolin.

[0023] By adopting the above technical solution, a large amount of cross - linked ettringite can be generated after the co - hydration of metakaolin and fly ash, and it can also promote the hydration reaction on the surface of the steel slag aggregate, enhancing the bonding force between the cement paste and the steel slag aggregate, which helps to improve the compressive strength of the concrete.

[0024] In a second aspect, the present application provides a method for preparing high-strength and low-thermal-conductivity self-compacting concrete, adopting the following technical solution.

[0025] A method for preparing high-strength and low-thermal-conductivity self-compacting concrete, comprising the following steps: (1) Mix cement, mineral admixture, glass microspheres, fine aggregate, coarse aggregate, and ceramic fiber to obtain dry materials for standby; mix water, water reducer, and shrinkage-reducing agent to obtain an admixture solution for standby; (2) Add the admixture solution to the dry materials and stir to obtain a concrete mixture, and carry out in-mold curing on the concrete mixture. After reaching the specified age, high-strength and low-thermal-conductivity self-compacting concrete is obtained.

[0026] By adopting the above technical solution, in the present application, dry materials and an admixture solution are first prepared separately, and then the dry materials and the admixture solution are used to mix the concrete mixture. After curing, high-strength and low-thermal-conductivity self-compacting concrete can be obtained.

[0027] To sum up, the present application has the following beneficial effects: 1. The high-strength and low-thermal-conductivity self-compacting concrete of the present application can maintain ideal strength performance while improving the heat insulation performance, and is thus more suitable for applications in temperature-sensitive occasions such as underground spaces and exterior walls in cold regions. In addition, the ceramsite of the present application also provides a new consumption route for vanadium slag, and can effectively realize the recycling of waste.

[0028] 2. While using vanadium slag as the main raw material of ceramsite, the present application also adds clay as a binder, uses fly ash as an aluminum source to adjust the silica-aluminum ratio, and uses calcium carbonate as a pore-forming agent. During the calcination process, mineral phases such as quartz, plagioclase, and albite are formed inside the ceramsite, and calcium oxide generated after the decomposition of calcium carbonate can react with quartz to produce wollastonite, and wollastonite can cooperate with other mineral phases to help fully improve the strength of the ceramsite.

[0029] 3. The present application preferably uses bentonite as a mineral admixture and preferably selects the dosage range of bentonite. The water absorption and water release characteristics of bentonite are used to improve the workability of the mortar, make the hydration of cement more sufficient, and thus improve the heat insulation performance and mechanical properties of the concrete. Specific embodiments

[0030] The present application will be further described in detail below with reference to examples, preparation examples, and comparative examples. The raw materials involved in the present application can all be obtained commercially.

[0031] Preparation example of ceramsite The following takes Preparation Example 1 as an example for illustration.

[0032] Preparation Example 1 In this preparation example, the main component contents of vanadium slag, clay, and fly ash are shown in Table 1 (expressed in terms of oxide composition, not all listed).

[0033] Table 1 Main component contents of vanadium slag, clay, and fly ash (wt%) Sample <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[K2O]]> <![CDATA[Na2O]]> LOI Vanadium slag 76.56 1.17 1.10 4.33 0.26 0.43 0.16 6.22 Clay 57.68 13.31 6.42 1.54 1.79 2.84 1.09 10.31 Fly ash 44.95 28.36 6.9 5.44 1.31 0.85 0.17 4.96 In this preparation example, the ceramsite is prepared according to the following method: (1) Mix vanadium slag, clay, calcium carbonate, and fly ash, grind the mixture, then add water equivalent to 18% of the dry material weight and roll it to obtain green balls with an average particle size of 10 mm, and set aside; in this step, vanadium slag accounts for 55% of the total weight of the green balls, calcium carbonate accounts for 5% of the total weight of the green balls, fly ash accounts for 20% of the total weight of the green balls, and the balance is made up with clay to 100%; (2) Transfer the green balls to a sintering furnace, heat them up to 400 °C at a rate of 5 °C / min, preheat them at 400 °C for 30 min, after the preheating is completed, heat them up to the sintering temperature of 1100 °C at a rate of 10 °C / min, and after holding and calcining for 15 min, cool them naturally to obtain the ceramsite.

[0034] Preparation Example 2 The difference between this preparation example and Preparation Example 1 is that vanadium slag accounts for 57% of the total weight of the green balls.

[0035] Preparation Example 3 The difference between this preparation example and Preparation Example 1 is that vanadium slag accounts for 60% of the total weight of the green balls.

[0036] Preparation Example 4 In this preparation example, the main oxide composition of the glass powder is shown in Table 2 (minor impurities not included).

[0037] Table 2 Main component content of glass powder (wt%) Sample <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[Na2O]]> Vanadium slag 72.8 2.0 0.12 6.62 4.13 14.26 The difference between this preparation example and Preparation Example 1 is that in step (1) of preparing the ceramsite, the glass powder is also mixed with vanadium slag, clay, calcium carbonate, and fly ash, and the total of fly ash and vanadium slag accounts for 55% of the total weight of the green balls, the proportions of other components remain unchanged, and the weight ratio of fly ash to glass powder is 3:1.

[0038] Preparation Example 5 The difference between this preparation example and Preparation Example 4 is that the calcination temperature is 1130 °C.

[0039] Preparation Example 6 The difference between this preparation example and Preparation Example 4 is that the calcination temperature is 1150 °C.

[0040] Preparation Example 7 This preparation example is different from Preparation Example 4 in that the calcination temperature is 1170 °C.

[0041] Preparation Example 8 This preparation example is different from Preparation Example 7 in that the calcination time is 20 min.

[0042] Preparation Example 9 This preparation example is different from Preparation Example 7 in that the calcination time is 25 min.

[0043] Preparation Example 10 This preparation example is different from Preparation Example 7 in that the calcination time is 30 min. Examples

[0044] Examples 1 - 5 The following takes Example 1 as an example for illustration.

[0045] Example 1 In this example, the cement is P.O62.5 portland cement, the mineral admixture is Class F Grade II fly ash, the average particle size of the glass microspheres is 0.14 mm, the fine aggregate is light sand with a fineness modulus of 2.7, and the light sand is crushed from A5.0 grade aerated concrete block waste; the coarse aggregate is composed of ceramsite, steel slag and porous basalt gravel mixed in a weight ratio of 3:2:5. The ceramsite is prepared according to the method of Preparation Example 1. The steel slag meets the continuous gradation of 5 - 20 mm, the crushing value is 12.3%, and the 24-hour water absorption rate of the steel slag is 1.72%; the porous basalt gravel meets the continuous gradation of 15 - 31.5 mm, the crushing value is 10.3%, and the 24-hour water absorption rate is 1.51%; the water reducer is an anti-clay type water reducer with a water reduction rate of 35.7%, and the shrinkage reducing agent is a polyether type shrinkage reducing agent SRA; the average diameter of the ceramic fiber is 3.0 μm, the average length is 20 mm, and the thermal conductivity is 0.173 W / (m·K).

[0046] This example provides a high-strength and low-thermal-conductivity self-compacting concrete, which includes the following components: 330 kg of cement, 125 kg of mineral admixture, 25 kg of glass microspheres, 380 kg of fine aggregate, 500 kg of coarse aggregate, 115 kg of water, 10 kg of water reducer, 25 kg of shrinkage reducing agent, and 28 kg of ceramic fiber.

[0047] This example provides a preparation method for a high-strength and low-thermal-conductivity self-compacting concrete, including the following steps: (1) Mix the cement, mineral admixture, glass microspheres, fine aggregate, coarse aggregate, and ceramic fiber to obtain dry materials for standby; mix the water, water reducer, and shrinkage reducing agent to obtain an admixture solution for standby; (2) Add the admixture solution to the dry materials and stir to obtain a concrete mixture. Carry out in-mold curing on the concrete mixture, and high-strength and low-thermal-conductivity self-compacting concrete is obtained after reaching the age of 28 days.

[0048] As shown in Table 3, the main difference between Examples 1-5 lies in the different raw material ratios of the concrete.

[0049] Table 3 Raw material ratios of the concrete Sample Example 1 Example 2 Example 3 Example 4 Example 5 Cement / kg 330 335 345 350 355 Mineral admixture / kg 125 128 130 132 135 Glass microspheres / kg 25 26 28 29 30 Fine aggregate / kg 380 390 400 410 420 Coarse aggregate / kg 500 505 510 515 520 Water / kg 115 118 120 122 125 Water reducing agent / kg 10 10.5 11 11.5 12 Shrinkage reducing agent / kg 25 26 28 29 30 Ceramic fiber / kg 28 30 31 33 35 As shown in Table 4, the difference between Examples 5-14 lies in the different preparation examples of the ceramsite.

[0050] Table 4 Preparation examples of the ceramsite Example 15 The difference between this example and Example 14 is that the light sand is composed of broken aerated concrete and bottom ash from the power plant furnace mixed in a weight ratio of 3:2, and the bulk density of the bottom ash from the power plant furnace is 640 kg / m 3 .

[0051] Example 16 The difference between this example and Example 15 is that the mineral admixture is Class F Grade I fly ash.

[0052] Example 17 The difference between this example and Example 16 is that the mineral admixture also includes bentonite, and the weight of bentonite accounts for 25% of the total weight of the mineral admixture.

[0053] Example 18 The difference between this example and Example 17 is that the weight of bentonite accounts for 28% of the total weight of the mineral admixture.

[0054] Example 19 The difference between this example and Example 17 is that the weight of bentonite accounts for 30% of the total weight of the mineral admixture.

[0055] Example 20 The difference between this example and Example 19 is that the mineral admixture also includes metakaolin, and the weight of metakaolin accounts for 15% of the total weight of the mineral admixture.

[0056] Example 21 The difference between this example and Example 19 is that all the fly ash is replaced by metakaolin.

[0057] Comparative example Comparative example 1 In this comparative example, P.O62.5 Portland cement is selected, the light sand is shale ceramsite sand, with a bulk density of 644 kg / m 3 , the cylinder compressive strength is 5.4 MPa, the 24-hour water absorption rate is 1.82%, the bulk density of the lightweight aggregate is 672 kg / m 3 , the cylinder compressive strength is 8.3 MPa, the 24-hour water absorption rate is 1.45%, and the fineness modulus of the river sand is 2.7; the water reducing rate of the functional admixture is 36.2%; the composite admixture is composed of S95 slag powder, class F II fly ash and silica fume. Among them, the weight ratio of fly ash to slag is 1:1, and the weight ratio of fly ash to silica fume is 10:1; the average diameter of the polypropylene fiber is 3.5 μm, the average length is 2.6 mm, the average particle size of the glass beads is 0.14 mm, and the shrinkage reducing agent is polyether type shrinkage reducing agent SRA.

[0058] This comparative example provides a high crack-resistant lightweight high-strength self-compacting concrete, including the following components: 330 kg of cement, 125 kg of water, 200 kg of light sand, 180 kg of river sand, 490 kg of lightweight aggregate, 125 kg of composite admixture, 9.8 kg of functional admixture, 15 kg of glass beads, 24 kg of shrinkage reducing agent, and 1.8 kg of polypropylene fiber.

[0059] The preparation method of the high crack-resistant lightweight high-strength self-compacting concrete includes the following steps: (1) Mix the cement, light sand, river sand, lightweight aggregate, composite admixture, glass beads, and polypropylene fiber to obtain dry materials for standby; mix the water, functional admixture, and shrinkage reducing agent to obtain an admixture solution for standby; (2) Add the admixture solution to the dry materials and stir to obtain a concrete mixture, and perform in-mold curing on the concrete mixture. After reaching the 28-day age, high crack-resistant lightweight high-strength self-compacting concrete is obtained.

[0060] Comparative Example 2 The difference between this comparative example and Example 1 is that the coarse aggregate only includes ceramsite.

[0061] Comparative Example 3 The difference between this comparative example and Example 1 is that the coarse aggregate only includes steel slag.

[0062] Comparative Example 4 The difference between this comparative example and Example 1 is that the coarse aggregate only includes porous basalt gravel.

[0063] Comparative Example 5 The difference between this comparative example and Example 1 is that the raw materials of the concrete do not include ceramic fibers.

[0064] Comparative Example 6 ​The difference between this comparative example and Example 1 is that the light sand is replaced with river sand (fineness modulus 2.7) of the same weight.

[0065] Performance testing methods I. Thermal conductivity The thermal conductivity was tested in accordance with GB / T 32064-2015 "Transient plane heat source method for testing thermal conductivity and thermal diffusivity of building materials". After the test, based on the thermal conductivity measured in Comparative Example 1, the ratio of the thermal conductivity of each example and comparative example to the thermal conductivity of Comparative Example 1 was calculated, and this ratio was recorded as the relative thermal conductivity. The results are shown in Table 5.

[0066] II. Compressive strength The compressive strength was tested with reference to GB / T 50081-2019 "Standard for test methods of physical and mechanical properties of concrete". After the test, based on the compressive strength measured in Comparative Example 1, the ratio of the compressive strength of each example and comparative example to the compressive strength of Comparative Example 1 was calculated, and this ratio was recorded as the relative strength. The results are shown in Table 6.

[0067] Table 6 Test results Combined with Examples 1-5 and Comparative Example 1 and in combination with Table 5, it can be seen that the relative thermal conductivity measured in Examples 1-5 is lower and the relative strength is higher, indicating that the high-strength and low-thermal-conductivity self-compacting concrete of the present application has improved heat insulation performance while also having increased compressive strength, and its comprehensive performance is superior to that of conventional heat-insulating concrete.

[0068] Combined with Example 1 and Comparative Examples 2-4 and in combination with Table 5, it can be seen that when the coarse aggregate is compounded in the manner of the present application, the heat insulation and compressive strength of the concrete are more ideal. When only ceramsite is selected as the coarse aggregate, although the thermal conductivity of the concrete is lower, the compressive strength is also lower at the same time; when only steel slag or porous basalt gravel is selected as the coarse aggregate, although the compressive strength is higher, the thermal conductivity is also higher at the same time.

[0069] Combined with Example 1 and Comparative Example 5 and in combination with Table 5, it can be seen that when ceramic fiber is missing in the raw materials of the concrete, due to the fact that the heat transfer path cannot be fully segmented, the formation and expansion of microcracks cannot be effectively hindered, and the stress cannot be effectively dispersed, so the compressive strength of the concrete is lower and the thermal conductivity is higher, and the comprehensive performance is poor.

[0070] Combining Example 1 and Comparative Example 6 and referring to Table 5, it can be seen that when replacing the light sand with river sand, although the compressive strength of the concrete has increased, since the total weight of the fine aggregate remains unchanged while the density of the river sand is larger, the overall volume of the fine aggregate decreases, affecting the filling effect of the fine aggregate on the gaps between the coarse aggregates, resulting in the inability to effectively divide the heat transfer path. Coupled with the relatively large thermal conductivity of the river sand, the thermal conductivity of the concrete is relatively high and the thermal insulation effect is poor.

[0071] Combining Examples 5 - 7 and Example 8 and referring to Table 5, it can be seen that the relative strength measured in Example 8 is higher. This is because sodium oxide in the glass powder has a fluxing effect, promoting the combination between the raw material powders, and the addition of glass powder also makes the ceramsite contain more glassy bodies, thus being able to improve the mechanical properties of the ceramsite and helping to maintain a relatively high strength while improving the thermal insulation performance of the concrete.

[0072] Combining Example 8, Examples 9 - 14 and referring to Table 5, it can be seen that ceramsite calcined at 1130 - 1170 °C for 20 - 30 min is more conducive to improving the compressive strength of the concrete.

[0073] Combining Example 14 and Example 15 and referring to Table 5, it can be seen that autoclaved aerated concrete crushed materials and power plant bottom slag help to further improve the thermal insulation performance of the concrete.

[0074] Combining Example 15 and Example 16 and referring to Table 5, it can be seen that selecting Class F Grade I fly ash as a mineral admixture can more effectively improve the compressive strength of the concrete.

[0075] Combining Example 16, Examples 17 - 19 and referring to Table 5, it can be seen that when the mineral admixture contains 25 - 30% of bentonite, due to the water absorption - water release characteristics of bentonite improving the workability of the mortar and making the hydration of cement more sufficient, the concrete can thus have a relatively high compressive strength and a relatively low thermal conductivity.

[0076] Combining Example 19, Examples 20 - 21 and referring to Table 5, it can be seen that the compressive strength measured in Example 20 is higher than that in Example 19. This is because metakaolin can generate a large amount of cross - linked ettringite after co - hydrating with fly ash and can also promote the hydration reaction on the surface of the steel slag aggregate, thus helping to improve the compressive strength of the concrete. However, the compressive strength measured in Example 21 has decreased instead because the lack of fly ash leads to the inability to exert this synergistic effect, and only relying on metakaolin and bentonite cannot effectively improve the compressive strength of the concrete.

[0077] The above embodiments are merely explanations of the present application and do not limit the present application. After reading this specification, those skilled in the art can make modifications to the embodiments of the present application that do not contribute creatively, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A high-strength and low-thermal-conductivity self-compacting concrete, characterized in that It comprises components in the following parts by weight: 330 - 355 parts of cement, 125 - 135 parts of mineral admixture, 25 - 30 parts of glass microspheres, 380 - 420 parts of fine aggregate, 500 - 520 parts of coarse aggregate, 115 - 125 parts of water, 10 - 12 parts of water reducer, 25 - 30 parts of shrinkage reducing agent, 28 - 35 parts of ceramic fiber; the fine aggregate includes light sand, the coarse aggregate includes ceramsite, steel slag and porous basalt gravel, the ceramsite is calcined from green balls, and the green balls contain 55 - 60wt% of vanadium slag.

2. The high-strength and low-thermal-conductivity self-compacting concrete according to claim 1, wherein The ceramsite is prepared according to the following method: (1) Mix vanadium slag, clay, calcium carbonate and fly ash, grind the mixture, then add water and roll it into balls, and dry to obtain green balls for standby; (2) Transfer the green balls to a sintering furnace for preheating, continue heating to the sintering temperature after preheating is completed, and naturally cool after heat preservation calcination to obtain ceramsite.

3. The high-strength and low-thermal-conductivity self-compacting concrete according to claim 2, wherein, In step (1) of preparing the ceramsite, glass powder is also mixed with vanadium slag, clay, calcium carbonate and fly ash.

4. The high-strength and low-thermal-conductivity self-compacting concrete according to claim 2, wherein In step (2) of preparing the ceramsite, the calcination temperature is 1130 - 1170 °C.

5. The high-strength and low-thermal-conductivity self-compacting concrete according to claim 4, wherein, In step (2) of preparing the ceramsite, the calcination time is 20 - 30 min.

6. The high-strength and low-thermal-conductivity self-compacting concrete according to claim 1, wherein The light sand includes at least one of aerated concrete crushed materials and power plant bottom slag.

7. The high-strength and low-thermal-conductivity self-compacting concrete according to claim 1, characterized in that, The mineral admixture includes Class F Grade I fly ash.

8. The high-strength and low-thermal-conductivity self-compacting concrete according to claim 7, wherein The mineral admixture includes bentonite, and the weight of the bentonite accounts for 25 - 30% of the total weight of the mineral admixture.

9. The high-strength and low-thermal-conductivity self-compacting concrete according to claim 8, characterized in that, The mineral admixture also includes metakaolin.

10. The preparation method of the high-strength and low-thermal-conductivity self-compacting concrete according to any one of claims 1-9, characterized in that, It includes the following steps: (1) Mix cement, mineral admixture, glass microspheres, fine aggregate, coarse aggregate and ceramic fiber to obtain dry materials for standby; mix water, water reducer and shrinkage reducing agent to obtain an admixture solution for standby; (2) Add the admixture solution to the dry materials and stir to obtain a concrete mixture, and perform in - mold curing on the concrete mixture to obtain high - strength and low - thermal - conductivity self - compacting concrete after reaching the specified age.

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