Thermal insulation concrete as well as preparation method and application thereof

Abstract

The invention relates to the technical field of building materials, in particular to thermal insulation concrete and a preparation method and application thereof. The heat insulation concrete is prepared from the following raw materials in parts by weight: 210 to 260 parts of cement, 140 to 190 parts of fly ash microbeads, 0 to 35 parts of silica fume, 280 to 350 parts of medium sand, 30 to 40 parts of light sand, 130 to 160 parts of light coarse aggregate, 1 to 4 parts of fiber material, 0.1 to 0.5 part of thickening agent, 3 to 8 parts of water reducing agent, 2 to 6 parts of early strength agent, 0.05 to 0.15 part of expanding agent, 0.07 to 0.12 part of air entraining agent, 0 to 4 parts of crystalline flake graphite and 180 to 240 parts of water. The heat insulation concrete has good heat insulation performance, certain mechanical property and durability.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to a heat-insulating concrete, a preparation method thereof, and an application thereof. Background Art

[0002] The construction industry emits about half of the greenhouse gases, which mainly come from fossil fuels used in heating, cooling, power supply, and construction processes; in order to reduce greenhouse gas emissions, green, low-carbon, safe, comfortable, and highly energy-efficient buildings with low operating energy consumption, high comfort, and high durability have become one of the target directions for building development. In highly energy-efficient buildings, the energy consumption of the thermal bridge part is particularly significant. Focusing on protecting the thermal bridge part can effectively reduce the overall energy consumption of the building. Since the thermal conductivity coefficients of concrete and brick masonry are relatively high, a thermal bridge will be formed at the part of the foundation beam or masonry strip foundation where the bottom of the inner partition wall on the first floor of the building is in direct contact with the soil. Due to the long length of the inner partition wall, the thermal bridge energy consumption formed is huge, and it is necessary to perform thermal bridge treatment on it to reduce energy consumption.

[0003] The methods for thermal bridge treatment include setting a continuous thermal insulation layer upward or downward along the wall at the thermal bridge to reduce thermal conductivity. In the prior art, when treating the thermal bridge of the inner partition wall on the first floor of a building, the method of setting a continuous thermal insulation layer is mostly selected, such as the method of wrapping a thermal insulation board at the bottom, or pasting vacuum boards or laying thermal insulation mortar on both sides of the inner partition wall. However, the method of wrapping a thermal insulation board has high construction difficulty, high cost, long construction period, and certain safety hazards; the method of pasting vacuum boards or laying thermal insulation mortar also has the defect of high cost, will affect the interior finish layer, and there is a risk of bulging and failure of the vacuum board after using for a certain period of time. If starting from the concrete itself, when meeting the strength requirements of the application scenario, reducing its thermal conductivity coefficient will be able to solve the above problems. Existing concretes cannot meet the usage requirements in terms of both strength and heat insulation performance at the same time. For example, the thermal conductivity coefficient of ceramsite aerated concrete is relatively low, but its internal pores are mainly open pores, with high water absorption rate, small softening coefficient, and the masonry strength is easily affected. Summary of the Invention

[0004] Therefore, the present invention provides a heat-insulating concrete, a preparation method thereof, and an application thereof, and uses a specific raw material ratio to obtain a heat-insulating concrete with a low thermal conductivity coefficient and certain mechanical properties, which can be applied in building structures to reduce the energy consumption at the thermal bridge.

[0005] For this purpose, the present invention provides the following technical solutions.

[0006] The present invention provides a heat-insulating concrete, which comprises raw materials in the following parts by weight: 210-260 parts of cement, 140-190 parts of fly ash microspheres, 0-35 parts of silica fume, 280-350 parts of medium sand, 30-40 parts of light sand, 130-160 parts of light coarse aggregate, 1-4 parts of fiber material, 0.1-0.5 parts of thickening agent, 3-8 parts of water-reducing agent, 2-6 parts of early strength agent, 0.05-0.15 parts of expansion agent, 0.07-0.12 parts of air-entraining agent, 0-4 parts of flake graphite, and 180-240 parts of water.

[0007] Among them, the medium sand is the medium sand in Zone II specified in GB / T 14684-2022 "Sand for construction".

[0008] The light sand is a material that conforms to GB / T 17431.1-2010 "Lightweight aggregates and their test methods - Part 1: Lightweight aggregates", and the particle size is below 4.75 mm.

[0009] The light coarse aggregate is a material that conforms to GB / T 17431.1-2010 "Lightweight aggregates and their test methods - Part 1: Lightweight aggregates", and the particle size is above 4.75 mm.

[0010] Fly ash microspheres are a new type of ultra-fine powder material, which is a sub-micron, regular spherical powder material selected and processed from high-quality fly ash through a unique process. Its chemical components are silicon dioxide and alumina, with pozzolanic activity and relatively low thermal conductivity.

[0011] Optionally, the above heat-insulating concrete comprises raw materials in the following parts by weight: 210-260 parts of cement, 140-190 parts of fly ash microspheres, 15-30 parts of silica fume, 280-350 parts of medium sand, 30-40 parts of light sand, 130-160 parts of light coarse aggregate, 1-4 parts of fiber material, 0.1-0.5 parts of thickening agent, 3-8 parts of water-reducing agent, 2-6 parts of early strength agent, 0.05-0.15 parts of expansion agent, 0.10-0.11 parts of air-entraining agent, 2-4 parts of flake graphite, and 180-240 parts of water.

[0012] Optionally, the heat-insulating concrete satisfies at least one of the following conditions:

[0013] (1) The light sand includes at least one of expanded perlite and expanded vitrified microspheres;

[0014] (2) The light coarse aggregate includes clay ceramsite; optionally, the clay ceramsite includes clay silt ceramsite;

[0015] (3) The fiber material includes at least one of polypropylene fiber and basalt fiber; optionally, the length of the fiber material is 6-9 mm;

[0016] (4) The thickener includes hydroxypropyl methylcellulose;

[0017] (5) The water reducing agent includes polycarboxylate water reducing agent; Naphthalene series water reducing agent and sulfonate series water reducing agent have relatively high energy consumption and formaldehyde risk, and their application scope is limited. Without special necessity, they are not used here;

[0018] (6) The early strength agent includes nanocrystalline nuclei;

[0019] (7) The expansive agent includes plastic expansive agent;

[0020] (8) The air entraining agent includes sodium dodecylbenzenesulfonate air entraining agent.

[0021] Typically and non - restrictively, the cement includes ordinary portland cement and portland cement, with a strength grade of 42.5 MPa.

[0022] The present invention provides a method for preparing the above - mentioned heat - insulating concrete, which includes the following steps: taking raw materials according to weight parts, mixing, pouring, vibrating and compacting, and curing to obtain the heat - insulating concrete.

[0023] Optionally, the vibration frequency of the vibrating and compacting is 80 - 100 Hz, the time is 10 - 15 s, and the number of times is 1 - 3 times.

[0024] Optionally, the curing includes static stopping at 20 - 30 °C for 2 - 6 h, heating to 50 - 60 °C at a heating rate of 10 - 20 °C / h, heat - preserving for 4 - 8 h, and cooling to 20 - 30 °C at a cooling rate of 10 - 20 °C / h.

[0025] The present invention provides a heat - insulating wall, which is formed on a building base. The building base includes a horizontally extending building support member and a horizontally laid building support layer. The heat - insulating wall includes: a heat - insulating layer, which is located above the building support layer and is laid along the building support layer; a wall body, which includes a first section and a second section. The second section is fixedly arranged on the upper side of the first section. The first section is formed on the building support member and is in contact with the building support member. The heat - insulating layer is in contact with the first section; The first section includes the above - mentioned heat - insulating concrete or the heat - insulating concrete prepared by the above - mentioned preparation method. The second section is fixedly arranged on the upper side of the first section and extends upward, such as extending to between the top beam or the bottom plate of the first floor of the building.

[0026] Among them, the building support layer includes a building floor support layer and a building ground support layer. The building support layer is provided with a rammed earth layer, a leveling layer, etc.; The building support member can be a ground beam or a rigid strip foundation located below the elevation of the building ground waterproof layer. The second section is a wall body in the general sense in the art.

[0027] The heat-insulating wall is arranged inside the building structure and can be used as an interior partition wall or a strip foundation of the building. By using heat-insulating materials in the first section, the first section located at the lower part of the wall body itself has heat-insulating function. The first section and the thermal insulation layer together constitute the heat-insulating barrier at the bottom of the wall. Their combined action is used to isolate a large number of thermal bridges generated by direct contact with the soil or foundation, so as to weaken the thermal bridges. By arranging the first section including heat-insulating materials, the construction step of covering the thermal insulation and waterproof layer at the foundation part of the wall can be cancelled during construction. Moreover, the first section that can weaken the thermal bridge can be directly laid on site during construction. Before laying the second section, the heat-insulating wall first lays the first section with heat-insulating materials at a certain height at the bottom, and then lays the second section with ordinary bricks on it. By using the first section to partially weaken the thermal bridge transmitted from the wall foundation, the construction efficiency at this place can be greatly improved, and the construction difficulty and cost can be reduced.

[0028] Optionally, the first section further includes waterproof materials. The first section penetrates through the thermal insulation layer and extends to the bottom of the thermal insulation layer, enabling the first section to have both heat-insulating and waterproof functions, and can save the construction step of specially setting a waterproof layer below the wall, thereby improving the construction efficiency as a whole.

[0029] Optionally, it further includes a waterproof layer. The waterproof layer is arranged on the building support layer, at the bottom of the thermal insulation layer and in contact with the first section. On the basis that the first section further includes waterproof materials, the contact between the waterproof layer and the first section can form a complete and continuous waterproof process on the building base to ensure the waterproof function. For example, waterproof mortar can be used at the bottom of the first section, and the waterproof layer is in contact with the waterproof mortar, which can not only help the first section bond more closely with the building support member, but also make the waterproof layer continuous to ensure the waterproof function.

[0030] Optionally, it further includes a decorative layer. The decorative layer is located on the side of the second section and extends downward to cover the side of the first section to improve the aesthetic degree of the exterior of the wall body.

[0031] The present invention provides a building structure, including the above-mentioned heat-insulating concrete or the heat-insulating concrete prepared by the above-mentioned preparation method, or the above-mentioned heat-insulating wall. Since the building structure includes a heat-insulating wall and has the same effect as the heat-insulating concrete or the heat-insulating wall, it will not be elaborated here.

[0032] The beneficial effects of the present invention are:

[0033] The heat-insulating concrete provided by the present invention comprises raw materials in the following parts by weight: 210-260 parts of cement, 140-190 parts of fly ash microspheres, 0-35 parts of silica fume, 280-350 parts of medium sand, 30-40 parts of light sand, 130-160 parts of light coarse aggregate, 1-4 parts of fiber material, 0.1-0.5 part of thickening agent, 3-8 parts of water reducing agent, 2-6 parts of early strength agent, 0.05-0.15 part of expansive agent, 0.07-0.12 part of air-entraining agent, 0-4 parts of flake graphite, and 180-240 parts of water. The dry apparent density of the heat-insulating concrete can reach 850 kg / m 3 Hereinafter, the thermal conductivity is below 0.15 W / (m·K), the compressive strength ≥ 6.3 MPa, the softening coefficient ≥ 0.8, and it has good heat-insulating performance, certain mechanical properties and durability. Among them, the fly ash microspheres, light coarse aggregate, light sand used in this application, and the foamed cement slurry formed after adding the air-entraining agent are mostly closed porous structures, which can improve the heat preservation performance of the material. And the relatively high content of closed porous structures makes the material absorb less water and the strength is less affected by humidity; that is, this heat-insulating concrete reduces the moisture intrusion path through the coordinated design of high-closed-cell materials and closed-cell bubbles, making the heat-insulating concrete have strong mechanical stability. The use of the thickening agent can improve the state of the concrete and is beneficial to the air-entraining agent to play its role. The addition of silica fume can further reduce the thermal conductivity of the heat-insulating concrete and improve its heat preservation and insulation performance. Flake graphite can help reduce the thermal conductivity of the concrete while maintaining the mechanical properties of the concrete. The combination of the dosages of cement, fly ash microspheres, silica fume, medium sand, light sand, and light coarse aggregate can reduce the dry apparent density of the heat-insulating concrete, and at the same time, the introduction of uniform and fine bubbles can be achieved only by adding the air-entraining agent without the use of additional foaming agents, saving the raw material dosage.

[0034] The heat-insulating wall provided by the present invention is formed on a building base. The building base includes a horizontally extending building support member and a horizontally laid building support layer. The heat-insulating wall includes: a heat preservation layer, located above the building support layer and laid along the building support layer; a wall body, which includes a first section and a second section, the second section is fixedly arranged on the upper side of the first section, the first section is formed on the building support member and is in contact with the building support member, and the heat preservation layer is in contact with the first section; the first section includes the above-mentioned heat-insulating concrete or the heat-insulating concrete prepared by the above-mentioned preparation method. The above-mentioned heat-insulating concrete or the heat-insulating concrete prepared by the above-mentioned preparation method plays a role in filling and heat preservation and insulation. The first section including them also has the function of heat insulation. The first section and the heat preservation layer can jointly form a heat-insulating barrier to isolate the heat bridge generated by the contact between the wall and the soil or the base, and thus the covering of the lower heat-insulating layer of the wall can be omitted, reducing the construction difficulty and construction cost. Description of the Drawings

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a schematic structural diagram of the heat-insulating wall provided in Embodiment 18 of the present invention.

[0037] Explanation of reference numerals: 1, thermal insulation layer; 2, first section; 3, second section; 4, waterproof layer; 5, decorative layer; 6, building support member. Specific embodiments

[0038] The following embodiments are provided to better further understand the present invention, which is not limited to the best embodiment, and does not limit the content and protection scope of the present invention. Any product that is the same as or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features falls within the protection scope of the present invention.

[0039] For those not specifying specific experimental steps or conditions in the embodiments, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments not indicating the manufacturer, they are all conventional reagent products that can be obtained through commercial purchase.

[0040] Experimental raw materials

[0041] Cement: commercially available P·O 42.5 ordinary Portland cement.

[0042] Silica fume: commercially available SF90-R silica fume.

[0043] Fiber material: commercially available polypropylene fiber with a length of 6 mm.

[0044] Thickening agent: commercially available hydroxypropyl methyl cellulose with a viscosity of 40000 Pa·s.

[0045] Water reducing agent: standard polycarboxylate high-performance water reducing agent with a water reducing rate of not less than 25%.

[0046] Expansive agent: commercially available azo compound plastic expansive agent, with a yellow powder appearance.

[0047] Medium sand: commercially available medium sand in Zone II.

[0048] Flake graphite: commercially available 200-mesh flake graphite.

[0049] Light sand: commercially available expanded vitrified microspheres, with a bulk density of 120 kg / m 3。

[0050] Fly ash microspheres: commercially available, bulk density 2390 kg / m 3 , particle size D50 ≤ 15 μm.

[0051] Early strength agent: The crystal nucleus type early strength agent produced by Hebei Sankai Shenfa Technology Co., Ltd., the crystal nucleus type early strength agent prepared by the method of Example 7 in the patent application number CN202211009448.0.

[0052] Light coarse aggregate: The particle size of the silt clay ceramsite is 5 - 10 mm (passing through a 4.75 mm square hole sieve, taking the sieve residue), bulk density 300 kg / m 3 。

[0053] Air-entraining agent: Commercially available dodecylbenzenesulfonic acid sodium air-entraining agent.

[0054] Examples 1 - 15

[0055] Examples 1 - 15 provide a heat-insulating concrete and its preparation method. Among them, expanded vitrified microspheres are used as the light sand, silt clay ceramsite is used as the light coarse aggregate, polypropylene fiber is used as the fiber material, hydroxypropyl methylcellulose is used as the thickening agent, polycarboxylate superplasticizer is used as the water-reducing agent, nano crystal nucleus early strength agent is used as the early strength agent, calcium oxide-based concrete expansion agent is used as the expansion agent, and dodecylbenzenesulfonic acid sodium air-entraining agent is used as the air-entraining agent. The size of the cast component is length × width × height: 600 mm × 200 mm × 200 mm.

[0056] Weigh the raw materials according to the raw material ratios (unit: kg / m 3 ) given in Tables 1 and 2 for standby. In Examples 1 - 15, the total amount of the binder materials (cement, fly ash microspheres, silica fume) is fixed at 410 kg / m 3 , among which the fly ash microspheres are fixed at 160 kg / m 3 , and the water-binder ratio is 0.52. The preparation is carried out according to the following method:

[0057] (1) Mix all the raw materials to obtain a concrete mixture, carry out the embedding operation. After the embedding is completed, carry out the casting. The cast component is vibrated and compacted by a vibrating table, the vibration frequency is 90 Hz, the time is 15 s, and it is repeated 1 - 3 times until there are no bubbles on the surface of the concrete.

[0058] (2) Keep the vibrated and compacted component in a static area at 25°C for 4 h, then send it to the curing room, heat it up to 55°C at a rate of 15°C / h, keep it warm for 5 h, and then cool it down to 25°C at a rate of 15°C / h to obtain the heat-insulating concrete.

[0059] Table 1

[0060] Cement Fly ash microspheres Silica fume Medium sand Light sand Light coarse aggregate Fiber material Example 1 250 160 0 300 36 150 3 Example 2 235 160 15 300 36 150 3 Example 3 230 160 20 300 36 150 3 Example 4 225 160 25 300 36 150 3 Example 5 220 160 30 300 36 150 3 Example 6 215 160 35 300 36 150 3 Example 7 225 160 25 300 36 150 3 Example 8 225 160 25 300 36 150 3 Example 9 225 160 25 300 36 150 3 Example 10 225 160 25 300 36 150 3 Example 11 225 160 25 300 36 150 3 Example 12 225 160 25 300 36 150 3 Example 13 225 160 25 300 36 150 3 Example 14 225 160 25 300 36 150 3 Example 15 225 160 25 300 36 150 3 Example 16 215 190 0 350 30 160 1 Example 17 260 140 35 280 40 130 4 Comparative Example 1 210 160 40 300 36 150 3 Comparative Example 2 225 160 25 300 36 150 3 Comparative Example 3 225 160 25 300 36 150 3 Comparative Example 4 225 160 25 300 36 150 3 Comparative Example 5 200 200 35 270 55 120 9 Comparative Example 6 270 120 0 360 20 170 0

[0061] Table 2

[0062] Thickening agent Water reducing agent Early strength agent Expansion agent Air entraining agent Flake graphite Water Example 1 0.3 5 4 0.13 0.10 2 213.2 Example 2 0.3 5 4 0.13 0.10 2 213.2 Example 3 0.3 5 4 0.13 0.10 2 213.2 Example 4 0.3 5 4 0.13 0.10 2 213.2 Example 5 0.3 5 4 0.13 0.10 2 213.2 Example 6 0.3 5 4 0.13 0.10 2 213.2 Example 7 0.3 5 4 0.13 0.07 2 213.2 Example 8 0.3 5 4 0.13 0.08 2 213.2 Example 9 0.3 5 4 0.13 0.09 2 213.2 Example 10 0.3 5 4 0.13 0.10 2 213.2 Example 11 0.3 5 4 0.13 0.11 2 213.2 Example 12 0.3 5 4 0.13 0.12 2 213.2 Example 13 0.3 5 4 0.13 0.10 0 213.2 Example 14 0.3 5 4 0.13 0.10 3 213.2 Example 15 0.3 5 4 0.13 0.10 4 213.2 Example 16 0.5 3 6 0.05 0.12 2 240 Example 17 0.1 8 2 0.15 0.08 4 180 Comparative Example 1 0.3 5 4 0.13 0.1 2 213.2 Comparative Example 2 0.3 5 4 0.13 0.05 2 213.2 Comparative Example 3 0.3 5 4 0.13 0.15 2 213.2 Comparative Example 4 0.3 5 4 0.13 0.1 6 213.2 Comparative Example 5 0.3 5 4 0.13 0.10 2 213.2

[0063]

[0064] Examples 16 - 17

[0065] Examples 16 - 17 provide a heat - insulating concrete and its preparation method. The difference from Example 1 is only that the raw material ratio is different. The raw material ratios in Examples 16 - 17 are shown in Tables 1 and 2 (unit: kg / m 3 ).

[0066] Comparative Examples 1 - 6

[0067] Comparative Examples 1 - 6 provide a heat - insulating concrete and its preparation method. The difference from Example 1 is only that the raw material ratio is different. The raw material ratios in Comparative Examples 1 - 6 are shown in Tables 1 and 2 (unit: kg / m 3 ).

[0068] Example 18

[0069] This example provides a heat - insulating wall. The following refers to Figure 1 describe the heat - insulating wall provided in this example.

[0070] The heat - insulating wall provided in this example can be a wall structure at the bottom that needs to be thermally bridged, such as the inner wall on the first floor of an energy - saving building, the inner partition wall at the separation between the energy - saving and non - energy - saving floors of a building. The heat - insulating wall is formed on a building base. The building base includes a horizontally extending building support member 6 and a horizontally laid building support layer. The heat - insulating wall includes: a thermal insulation layer 1, which is located above the building support layer and is laid along the building support layer; a wall body, which includes a first section 2 and a second section 3. The second section 3 is fixedly arranged on the upper side of the first section 2. The first section 2 is formed on the building support member 6 and is in contact with the building support member 6. The thermal insulation layer 1 is in contact with the first section 2. The first section 2 includes the heat - insulating concrete prepared in Examples 1 - 17. Specifically, the building support layer includes a building floor support layer and a building ground support layer. The building support layer is provided with a rammed earth layer, a leveling layer, etc., and can be a ground cushion layer. The building support member 6 can be a ground beam or a rigid strip foundation below the elevation of the building ground waterproof layer 4, and its thickness is greater than the thickness of the first section 2. The second section 3 is a wall body in the general sense in the art.

[0071] The heat - insulating wall is arranged in a building structure and is applied in building inner partitions and strip foundations. Among them, the thermal insulation layer 1 is arranged under the ground to isolate the thermal bridge between floors; the first section 2 is arranged at the bottom of the wall to isolate the thermal bridge at the bottom of the wall.

[0072] In some embodiments, the first section 2 further includes a waterproof material. The first section 2 penetrates through the insulation layer 1 and extends to the bottom of the insulation layer 1, enabling the first section 2 to have the functions of heat insulation and waterproofing simultaneously, which can eliminate the construction step of specially setting a waterproof layer 4 below the wall body, thereby improving the construction efficiency as a whole.

[0073] In some embodiments, a waterproof layer 4 is further included. The waterproof layer 4 is disposed above the building support layer. The waterproof layer 4 is located at the bottom of the insulation layer 1 and is in contact with the first section 2. On the basis that the first section 2 further includes a waterproof material, the contact between the waterproof layer 4 and the first section 2 can form a complete and continuous waterproof process on the building base to ensure the waterproof function. For example, waterproof mortar can be used at the bottom of the first section 2, and the waterproof layer 4 is in contact with the waterproof mortar, which can not only help the first section 2 bond more closely with the building support member 6, but also make the waterproof layer 4 continuous to ensure the waterproof function.

[0074] In some embodiments, a decorative layer 5 is further included. The decorative layer 5 is located on the side of the second section 3 and extends downward to cover the side of the first section 2 to improve the aesthetic degree of the exterior of the wall body.

[0075] According to this embodiment, another method further provides a building structure, including the heat-insulating concrete prepared in Embodiments 1 to 17 or the above-mentioned heat-insulating wall. The building structure can be a basement structure, a building structure, or any structure with a wall. For example, when the heat-insulating wall is a heat-insulating interior partition wall, this kind of interior partition wall structure is applicable to any part of the first-floor interior partition wall that can be a structure with or without a basement, the interior partition wall part in the building, etc., where heat bridge breaking treatment is required for indoor walls. The first section 2 in the heat-insulating wall can be constructed by using heat-insulating concrete on-site during construction. When constructing the heat-insulating wall, by first using heat-insulating concrete to build the first section 2 at the bottom, and then building the second section 3 with ordinary bricks on the first section 2, the heat bridge brought by the bottom of the wall is weakened by using the first section 2, which can improve the overall construction efficiency of the heat-insulating wall and reduce the construction cost.

[0076] Test Example 1

[0077] Test the dry apparent density, 28-day compressive strength, thermal conductivity, and softening coefficient of the final products obtained in Test Examples 1 to 17. Among them, the test methods for the dry apparent density and softening coefficient refer to the test method in Appendix B of JGJ / T 12-2021 "Technical Standard for Application of Lightweight Aggregate Concrete". The test method for the thermal conductivity refers to the test method given in GB / T 10294-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Guarded Hot Plate Method". The test method for the 28-day compressive strength refers to the test method given in GB / T 50081-2019 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The obtained data are shown in Table 3.

[0078] Table 3

[0079]

[0080]

[0081] It can be seen from Table 3 that with the increase of the silica fume content, the thermal conductivity of the final product concrete continuously decreases, but the 28-day compressive strength first increases and then decreases. When the silica fume content increases from 25 parts in Example 4 to 30 parts in Example 5, the 28-day compressive strength decreases by 4%. When the silica fume content increases from 30 parts in Example 5 to 35 parts in Example 6, the thermal conductivity does not change significantly, while the 28-day compressive strength decreases by about 6%. Therefore, the silica fume content should be maintained within 35 parts. An excessive silica fume content has no further effect on the reduction of the thermal conductivity, but will significantly reduce the 28-day compressive strength of the final product concrete. Comparing with Comparative Example 1 again, with the silica fume content up to 40 parts, the dry apparent density of the concrete further decreases, but this simultaneously causes the generation of microcracks inside the concrete, resulting in a significant decrease in the 28-day compressive strength and an increase in the thermal conductivity.

[0082] With the increase of the air-entraining agent content, both the thermal conductivity and the 28-day compressive strength of the final product concrete gradually decrease. The amount of the air-entraining agent in Example 11 is 0.11 part, and the amount of the air-entraining agent in Example 12 is 0.12 part. It can be seen from the data of the two that in Examples 11 and 12, with the increase of the air-entraining agent content, the thermal conductivity does not decrease further, while the 28-day compressive strength decreases significantly. Therefore, the air-entraining agent content should be maintained within 0.12 parts, otherwise it will significantly reduce the 28-day compressive strength of the final product concrete and will not further reduce the thermal conductivity at the same time. In Comparative Example 2, 0.05 part of the air-entraining agent is used, which is 0.05 part less than that in Example 10. The concrete strength increases, but the internal pores decrease and the thermal conductivity increases. In Comparative Example 3, 0.15 part of the air-entraining agent is used. The excessive air-entraining agent seriously affects the concrete performance. There are connected pores inside the hardened concrete surface, which is conducive to heat transfer, resulting in an increase in the thermal conductivity. At the same time, the connected pores increase the water absorption of the concrete and the softening coefficient becomes smaller.

[0083] Flake graphite can effectively reduce the thermal conductivity of concrete, and the higher the content of flake graphite, the lower the thermal conductivity of concrete, as shown in Examples 10, 13, 14, and 15. However, the incorporation of flake graphite will inevitably affect the compressive strength of concrete and needs to be added as appropriate. In Comparative Example 4, the output of flake graphite is as high as 6 parts. Excessive flake graphite causes defects inside the concrete and reduces its compressive strength.

[0084] For Comparative Examples 5 and 6 where the proportions of cement, fly ash microspheres, medium sand, light sand, light coarse aggregate, and fiber material are not within the scope specified in this application, due to improper proportions among the raw materials, the 28-day compressive strength in Comparative Example 5 is relatively low, being 5.8 MPa, and in Comparative Example 6, the thermal conductivity is as high as 0.156 W / (m·K), so it cannot be used as thermal insulation concrete.

[0085] Obviously, the above embodiments are merely examples given for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, based on the above description, other different forms of changes or modifications can be made. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A thermal insulation concrete, characterized in that: The invention comprises the following raw materials in parts by weight: 210-260 parts of cement, 140-190 parts of fly ash beads, 0-35 parts of silica fume, 280-350 parts of medium sand, 30-40 parts of light sand, 130-160 parts of light coarse aggregate, 1-4 parts of fiber material, 0.1-0.5 parts of thickener, 3-8 parts of water reducer, 2-6 parts of early strength agent, 0.05-0.15 parts of expansion agent, 0.07-0.12 parts of air entraining agent, 0-4 parts of flake graphite, and 180-240 parts of water.

2. The thermal insulation concrete according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 210-260 parts of cement, 140-190 parts of fly ash beads, 15-30 parts of silica fume, 280-350 parts of medium sand, 30-40 parts of light sand, 130-160 parts of light coarse aggregate, 1-4 parts of fiber material, 0.1-0.5 parts of thickener, 3-8 parts of water reducer, 2-6 parts of early strength agent, 0.05-0.15 parts of expansion agent, 0.10-0.11 parts of air entraining agent, 2-4 parts of flake graphite, and 180-240 parts of water.

3. The thermal insulation concrete according to claim 1 or 2, characterized in that: At least one of the following conditions is met: (1) The light sand comprises at least one of expanded perlite and expanded vitrified microspheres; (2) The light coarse aggregate includes clay ceramsite; (3) The fiber material includes at least one of polypropylene fiber and basalt fiber; (4) The thickener comprises hydroxypropyl methylcellulose; (5) The water reducer includes a polycarboxylate water reducer; (6) The early strength agent includes at least one of a crystal nucleus type early strength agent and a calcium formate type early strength agent; (7) The expansion agent includes a plastic expansion agent; (8) The air-entraining agent includes at least one of sodium dodecylbenzene sulfonate air-entraining agent and triterpenoid saponin air-entraining agent.

4. A method for preparing the insulating concrete according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: taking raw materials according to weight proportions, mixing, pouring, vibrating and curing to obtain the heat-insulating concrete.

5. The preparation method according to claim 4, characterized in that: The vibration frequency of the compaction is 80-100 Hz, the time is 10-15 s, and the number of times is 1-3 times; And / or, the curing includes standing at 20-30°C for 2-6h, heating to 50-60°C at a heating rate of 10-20°C / h, keeping warm for 4-8h, and cooling to 20-30°C at a cooling rate of 10-20°C / h.

6. A heat-insulating wall, characterized in that: Formed on a building substrate, the building substrate includes horizontally extending building support members and a flatly arranged building support layer, the heat-insulating wall includes: A thermal insulation layer, located above the building support layer and laid along the building support layer; The wall body comprises a first section and a second section, wherein the second section is fixedly arranged on the upper side of the first section, the first section is formed on the building support member and contacts the building support member, and the thermal insulation layer contacts the first section; The first section includes the insulating concrete according to any one of claims 1 to 3 or the insulating concrete prepared by the preparation method according to claim 4 or 5.

7. The heat-insulating wall according to claim 6, characterized in that: The first section also includes waterproof material, and the first section penetrates the thermal insulation layer and extends to the bottom of the thermal insulation layer.

8. The heat-insulating wall according to claim 7, characterized in that: It also includes a waterproof layer, which is arranged on the building support layer. The waterproof layer is located at the bottom of the insulation layer and is in contact with the first section.

9. The heat-insulating wall according to any one of claims 6 to 8, characterized in that: The invention also comprises a decoration layer, which is located on the side surface of the second section and extends downward to cover the side surface of the first section.

10. A building structure, characterized in that: It comprises the insulating concrete as described in any one of claims 1 to 3 or the insulating concrete prepared by the preparation method as described in claim 4 or 5, or the insulating wall as described in any one of claims 6 to 9.

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