A heat storage foam concrete and a preparation method thereof

Abstract

The present application relates to a kind of heat storage foam concrete and its preparation method, wherein, heat storage foam concrete, which is made of the following raw material composition by weight parts: cement 450~900 parts, auxiliary cementitious material 200~400 parts, phase change material 50~100 parts, water 150-300 parts, water reducing agent 2~4 parts, thickening agent 0.1-0.2 parts, plant fiber 4~6 parts and foam 12~28 parts.It has beneficial effects that, using sheet phase change material directly mixes with concrete, foam and other materials, saves the step of encapsulating phase change material, improves the heat storage effect of phase change material, selects expanded vermiculite as the carrier of phase change material, enhances the bonding strength between foam concrete interfaces, thereby achieving the effect of improving the strength of foam concrete.

Description

Technical Field

[0001] This invention relates to the field of building energy conservation technology, and in particular to a heat-storing foamed concrete and its preparation method. Background Technology

[0002] With the rapid development of the construction industry, reducing building energy consumption and improving the living environment have received widespread attention. Building operating energy consumption is caused by various factors such as ambient temperature and building performance characteristics. Studies show that walls account for about one-quarter of a building's operating energy consumption. Therefore, to achieve building energy conservation, it is necessary to utilize or store the energy lost in the building envelope.

[0003] Phase change materials (PCMs), as heat storage materials, can absorb a large amount of heat without significantly increasing the temperature of objects. Foamed concrete, on the other hand, is a good lightweight thermal insulation material and is widely used as a lightweight wall structure in buildings. Therefore, incorporating PCMs into foamed concrete can increase the heat storage capacity of building walls and reduce indoor temperature fluctuations to achieve energy conservation. However, PCMs are prone to liquid leakage during solid-liquid phase transitions, causing inconvenience in practical applications. Currently, to solve this problem, PCMs are encapsulated, for example, using microcapsules. However, the encapsulation process is complex and costly. The presence of these polymer films affects the heat conduction process, reducing the heat storage effect of the PCMs. At the same time, the poor interfacial bonding between the polymer film and foamed concrete leads to a decrease in the strength performance of the concrete, making it unsuitable for heat storage building materials with high strength requirements.

[0004] Therefore, there is a need to provide a new type of thermal storage foamed concrete to overcome the above-mentioned technical defects. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a thermal storage foam concrete and its preparation method, which solves the technical problems of poor thermal storage effect and low building strength performance of existing thermal storage foam concrete.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0009] In a first aspect, embodiments of the present invention provide a heat-storing foamed concrete, which is made from a composition of the following raw materials in parts by weight: 450-900 parts of cement, 200-400 parts of auxiliary cementitious material, 50-100 parts of phase change material, 150-300 parts of water, 2-4 parts of water-reducing agent, 0.1-0.2 parts of thickener, 4-6 parts of plant fiber and 12-28 parts of foam.

[0010] Cement provides strength support; auxiliary cementitious materials reduce the heat of hydration, lowering the risk of early cracking in foamed concrete and promoting later strength growth. Phase change materials primarily function as heat storage, improving the overall energy-saving performance of foamed concrete. Water-reducing agents reduce water content and increase concrete strength. Foam provides thermal insulation and reduces material weight. Thickeners primarily adjust the viscosity of the slurry, preventing phase change materials from floating and also improving the stability of foam within the slurry to some extent. Plant fibers, widely available, can enhance the tensile strength of concrete and reduce shrinkage cracking; compared to chemical fibers, plant fibers have higher tensile strength.

[0011] According to a preferred embodiment of the present invention, the heat storage foam concrete has a phase change material in sheet form, wherein each part by weight of phase change material includes, by weight: 170-240 parts of porous matrix material and 85-170 parts of phase change agent adsorbed inside the porous matrix material.

[0012] Phase change materials are pressed into sheets, which can be square, round, or other irregular shapes. Pressing can prevent leakage of the internal phase change agent during the solid-liquid phase change process without the need for encapsulation. The sheet-like phase change material is evenly distributed in concrete and can also act as a lightweight aggregate, which is beneficial to improving the strength of concrete.

[0013] According to a preferred embodiment of the present invention, the heat storage foam concrete has a sheet-like phase change material with an equivalent diameter of 8-12 mm and a thickness of 3-4 mm; the porous matrix material is expanded vermiculite; and the phase change agent is at least one of fatty acids, alkanes, polyols, alcohols, and esters.

[0014] The equivalent diameter of the sheet-like phase change material is 8-12 mm, and the thickness is 3-4 mm, which facilitates mixing with other slurries and allows for optimal heat storage. If the equivalent diameter or thickness is below these ranges, i.e., the sheet is too small, the risk of internal phase change agent leakage increases. Furthermore, due to the large specific surface area of ​​the porous matrix material, more slurry needs to be coated, leading to a decrease in the workability of the concrete. If the equivalent diameter or thickness is above these ranges, i.e., the sheet is too large, it will affect the overall compressive strength of the concrete. Additionally, to facilitate the pressing of the sheet-like phase change material (generally using a circular mold), it can be made into circular sheets with a diameter of 8-12 mm and a thickness of 3-4 mm.

[0015] According to a preferred embodiment of the present invention, the thermal storage foam concrete uses silicate cement as the cement; the auxiliary cementitious material is silica fume with a SiO2 content greater than 90%; the water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate greater than 25%; the thickener is hydroxypropyl methylcellulose with a viscosity of 80,000 to 100,000; and the plant fiber is coconut shell fiber with a length of 15-17 mm and an aspect ratio of 38-40.

[0016] Adding silica fume with a SiO2 content greater than 90% as an auxiliary cementitious material reduces the amount of cement used, resulting in a lower density phase change thermal storage foam concrete while maintaining the same strength. Hydroxypropyl methylcellulose has a viscosity of 80,000-100,000, ensuring uniform distribution of the phase change material in the slurry. If the viscosity is too low, the phase change material tends to float and aggregate, affecting the overall thermal storage performance; if the viscosity is too high, the concrete's workability deteriorates, making construction difficult. Coconut shell fiber is widely available and low-cost; using coconut shell fiber of the aforementioned size facilitates mixing and dispersion.

[0017] According to a preferred embodiment of the present invention, the heat storage foam concrete has a porous matrix material of modified expanded vermiculite with a particle size of 30-300 μm and a phase change agent of decanoic acid.

[0018] Vermiculite possesses excellent thermal conductivity and chemical stability. Modified expanded vermiculite exhibits a significantly increased interlayer spacing in its layered structure, resulting in a correspondingly larger volume expansion ratio. This allows for the stable adsorption of large amounts of phase change agents, thereby enhancing the heat storage performance of phase change thermal storage materials. Furthermore, vermiculite exhibits minimal morphological changes after expansion, maintaining its macroscopic solid state during the solid-liquid conversion of the phase change agent, effectively preventing leakage.

[0019] According to a preferred embodiment of the present invention, the heat-storing foamed concrete contains nano-foam with a foam density of 25-40 kg / m³. 3 .

[0020] The density of the foam should preferably not exceed 40 kg / m³. 3 To prevent foam from collapsing due to excessively high density; if the foam density is below 25 kg / m³, the foam should be kept within acceptable limits. 3 This can affect the molding of thermal storage foamed concrete; nano-sized foam has better stability. The advantage of directly adding foam instead of a foaming agent is its simple process and the elimination of the need for autoclaving, allowing for conventional curing. However, foamed concrete prepared by directly adding foam has mostly independent, closed pores, while directly adding a foaming agent creates interconnected pores, resulting in a relatively higher water absorption rate and making it unsuitable for applications in high-humidity environments.

[0021] Secondly, embodiments of the present invention provide a method for preparing thermal storage foamed concrete, comprising the following steps:

[0022] S1. Pretreatment of porous matrix material: Modify the porous matrix material, and then heat it to expand it to obtain a modified expanded porous matrix material.

[0023] S2. Adsorption of phase change agent: The phase change agent is dissolved in an organic solvent to prepare a phase change agent / organic solvent mixture, and then a modified expanded porous matrix material is added. The mixture is vacuum impregnated for 1-5 hours and then dried to obtain a modified expanded porous matrix material adsorbed with the phase change agent.

[0024] S3. Phase change material compression molding: The modified expanded porous matrix material adsorbed with phase change agent is continuously compressed under a pressure of 4-6 MPa to obtain sheet-like phase change material.

[0025] S4. Slurry preparation: First, mix cement, auxiliary cementitious materials and flaky phase change materials evenly, then add water, water-reducing agent and thickener and mix evenly to obtain slurry.

[0026] S5. Preparation of thermal storage foam concrete: Add alkali-treated plant fibers to the slurry and mix well, then add foam and mix well, pour into a mold and cure to obtain thermal storage foam concrete.

[0027] In the pressing process of sheet-like phase change materials, a pressure of 4-6 MPa is used to complete the extrusion molding of the phase change material, ensuring that the phase change agent does not leak during the phase change process. If the pressure is too low, molding is difficult; if the pressure is too high, it will affect the internal structure of the molded phase change material and cause leakage of the phase change agent.

[0028] According to a preferred embodiment of the present invention, the method for preparing the thermal storage foamed concrete,

[0029] In S1, the process of modifying the porous matrix material is as follows: the porous matrix material is placed in an inorganic salt solution, stirred for 1-2 hours, and then filtered to obtain the modified porous matrix material.

[0030] The heating and expansion process involves heating and expanding the modified porous matrix material at 700-800℃.

[0031] According to a preferred embodiment of the present invention, the method for preparing the thermal storage foamed concrete,

[0032] In S2, the organic solvent is ethanol; the drying conditions are: drying at 20-30℃.

[0033] In S5, the curing process is as follows: curing for 6-8 days at a temperature of 20-25℃ and a relative humidity of 85-90%.

[0034] According to a preferred embodiment of the present invention, the method for preparing the thermal storage foamed concrete,

[0035] In S3, the modified expanded porous matrix material adsorbed with phase change agent is subjected to a pressure of 4 MPa for 1.5 min to obtain a sheet-like phase change material with an equivalent diameter of 10 mm.

[0036] (III) Beneficial Effects

[0037] The beneficial effects of this invention are as follows: The thermal storage foamed concrete and its preparation method of this invention use sheet-like phase change materials to directly mix with concrete, foam and other materials, eliminating the step of encapsulating the phase change materials. Compared with the prior art, this simplifies the production process, saves production costs, and improves the thermal storage effect of the phase change materials. At the same time, the use of expanded vermiculite as a carrier for the phase change materials enhances the bonding strength of the interfaces between foamed concrete, thereby improving the strength of the foamed concrete.

[0038] Expanded vermiculite, as a carrier of phase change materials, has good thermal conductivity and chemical stability. Under the combined effect of inorganic salt modification and thermal activation, the interlayer spacing in its layered structure increases significantly, and the volume expansion factor increases accordingly. A large amount of phase change agent can be stably adsorbed through vacuum impregnation, thereby improving the heat storage effect of phase change thermal storage materials.

[0039] Vermiculite undergoes minimal morphological changes after expansion, maintaining its macroscopic solid form throughout the solid-liquid transition process of the phase change agent. Furthermore, by continuously pressing the modified expanded vermiculite with the phase change agent under pressure into sheets, leakage of the phase change agent can be prevented.

[0040] Vermiculite is a lightweight inorganic mineral material with strong bonding ability with foamed concrete matrix. It effectively solves the problem of poor compatibility between phase change heat storage materials and foamed concrete matrix, ensuring the mechanical properties of foamed concrete, while not affecting the lightweight characteristics of foamed concrete.

[0041] The heat-storing foamed concrete prepared by this invention has a dry density of 800-1500 kg / m³. 3 It has a compressive strength of 6-32 MPa and a thermal conductivity of 0.15-1.1 W / (m·K). Detailed Implementation

[0042] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to specific embodiments.

[0043] This invention proposes a thermal storage foamed concrete and its preparation method, which addresses the technical problems of poor thermal storage effect and low building strength performance of existing thermal storage foamed concrete. It uses sheet-like phase change materials to be directly mixed with concrete, foam and other materials, eliminating the step of encapsulating the phase change materials. Compared with the prior art, it can simplify the production process, save production costs, improve the thermal storage effect of the phase change materials, and enhance the bonding strength of the interfaces between foamed concrete, thereby improving the strength of the foamed concrete.

[0044] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0045] Example 1

[0046] This embodiment provides a method for preparing phase change thermal storage foamed concrete, the specific steps of which are as follows:

[0047] Step 1: Take 170 parts of vermiculite according to the mass ratio and put them into a sodium chloride modification solution with a concentration of 1.5 mol / L. Stir continuously for 1 hour, then filter dry to obtain modified vermiculite. Then place the modified vermiculite in a muffle furnace and heat at 750℃ for 1 hour to obtain modified expanded vermiculite.

[0048] Step 2: Add 85 parts of decanoic acid (99% purity) to 200 parts of ethanol (99.8% purity), stir for 0.5 h until the decanoic acid is fully dissolved to obtain a decanoic acid / ethanol mixed solution; then add modified expanded vermiculite to the mixed solution and vacuum impregnate for 1 h to obtain a blend.

[0049] Step 3: Place the blend in an oven and dry at 20°C for 1 hour to obtain decanoic acid / expanded vermiculite phase change material;

[0050] Step 4: The decanoic acid / expanded vermiculite phase change material is placed in a press and subjected to a pressure of 4 MPa for 2 minutes to obtain a circular sheet-shaped phase change material with a diameter of 10 mm and a thickness of 4 mm.

[0051] Step 5: For each cubic meter volume, pour 450 parts of ordinary silicate 42.5 cement, 200 parts of silica fume (SiO2 content 93%), and 50 parts of shaped phase change material into a mixer and stir for 1 minute to obtain a uniformly mixed dry material; then pour 160 parts of water, 2 parts of polycarboxylate superplasticizer (water reduction rate 30%), and 0.13 parts of hydroxypropyl methylcellulose (viscosity 100,000) into the dry material and continue stirring for 1 minute to obtain a uniformly mixed slurry;

[0052] Step 6: Add 4 parts of coconut shell fiber (pre-soaked in 0.5 mol / L NaOH solution for 1 hour and then dried) to the slurry and stir for 1.5 min; then add 26 parts of nano-scale foam (density 28 kg / m³) prepared by foaming with modified ionic foaming agent. 3 Stir again for 1.5 minutes to obtain a uniformly mixed phase change thermal storage foam concrete slurry.

[0053] Step 7: Pour the phase change thermal storage foam concrete slurry into the mold, and after molding, cure it for 6 days at a temperature of 20℃ and a relative humidity of 85% to obtain the phase change thermal storage foam concrete.

[0054] The test results of phase change thermal storage foamed concrete are as follows:

[0055] According to the dry density test conducted in accordance with JG / T 266-2011 "Foamed Concrete", the dry density of the phase change thermal storage foamed concrete prepared by the above method is 820 kg / m³. 3 .

[0056] The compressive strength of the phase change thermal storage foam concrete prepared by the above method was tested according to JG / T 266-2011 "Foamed Concrete". The compressive strength was 6.5 MPa after 28 days.

[0057] The thermal conductivity of the phase change thermal storage foamed concrete prepared by the above method was measured to be 0.194 W / (m·K) using a concrete thermal conductivity instrument, in accordance with the "Foamed Concrete" standard JG / T 266-2011.

[0058] Example 1, as the preferred embodiment, shows that when the dry density of phase change thermal storage foam concrete is low, it significantly improves the compressive strength compared to lightweight phase change thermal storage foam concrete with a compressive strength of less than 4 MPa, while maintaining the thermal conductivity within a relatively small range. This makes it more suitable for applications requiring higher compressive strength, such as for use as an interior partition wall.

[0059] Vermiculite, a lightweight inorganic mineral material, is selected as the carrier for the phase change material. It exhibits strong bonding with the foamed concrete matrix, effectively solving the problem of poor compatibility between the phase change thermal storage material and the foamed concrete matrix. This ensures the mechanical properties of the foamed concrete without affecting its lightweight characteristics. Furthermore, the combined effects of modification with sodium chloride solution and thermal activation significantly increase the interlayer spacing and volume expansion of vermiculite's layered structure. Vacuum impregnation further stabilizes and adsorbs a large amount of phase change agent, thereby enhancing the thermal storage effect of the phase change thermal storage material.

[0060] The added plant fiber is selected from coconut shell fibers with a length of 17mm and an aspect ratio of 40, which facilitates mixing and dispersion. At the same time, an alkaline solution is used to remove the biomass components and excess impurities from the plant fiber, thereby increasing the surface roughness of the fiber and strengthening its bonding ability with the paste, which is beneficial to improving the strength of the concrete.

[0061] Example 2-3

[0062] The differences between Examples 2-3 and Example 1 are detailed in Tables 1 and 2:

[0063] Table 1

[0064]

[0065] Table 2

[0066] Test Results Example 2 Example 3 <![CDATA[Dry density (kg / m 3 )]]> 822 825 Compressive strength (MPa) 6.0 6.2 Thermal conductivity (W / (m·K)) 0.201 0.210

[0067] The optimal mass ratio of the phase change agent decanoic acid to vermiculite is 1:2, and the optimal equivalent diameter of the sheet-shaped phase change material is 10 mm. When the amount of vermiculite is fixed, simply increasing the amount of decanoic acid or changing the diameter and thickness of the disc-shaped phase change material will not promote the reduction of thermal conductivity or the increase of compressive strength of phase change thermal storage concrete.

[0068] Examples 4-5

[0069] The differences between Examples 4-5 and Example 1 are detailed in Tables 3 and 4:

[0070] Table 3

[0071]

[0072]

[0073] Table 4

[0074] Test Results Example 4 Example 5 <![CDATA[Dry density (kg / m 3 )]]> 836 842 Compressive strength (MPa) 5.8 5.7 Thermal conductivity (W / (m·K)) 0.190 0.181

[0075] A comparative analysis of Examples 4 and 5 with Example 1 shows that as the content of shaped phase change material increases, the thermal conductivity decreases, meaning that the heat storage effect of phase change thermal storage foam concrete is better when the content of shaped phase change material increases; however, the compressive strength decreases. Therefore, in order to ensure compressive performance, the amount of shaped phase change material added should not be too much.

[0076] Examples 5-6

[0077] The differences between Examples 5-6 and Example 4 are detailed in Tables 5 and 6:

[0078] Table 5

[0079] Components in step 5 Example 6 Example 7 Ordinary silicate 42.5 cement 640 copies 900 copies silica ash 280 copies 400 copies water 230 copies 300 copies Polycarboxylate superplasticizer 2.75 copies 4 copies Hydroxypropyl methylcellulose 0.18 copies 0.2 copies Coconut shell fiber 5 copies 6 copies Foam 20 copies 12 copies

[0080] Table 6

[0081]

[0082]

[0083] Comparative analysis of Examples 5 and 6 with Example 4 shows that as the amount of cement and other components added increases, the dry density of the phase change thermal storage foam concrete increases significantly, and the corresponding compressive strength also increases. However, the thermal conductivity increases significantly, meaning that the thermal storage performance of the phase change thermal storage foam concrete decreases significantly. A series of theoretical references are provided here, which can be used to determine the proportions of each component based on the required strength.

[0084] Comparative Example 1

[0085] The difference between this comparative example and Example 1 is that:

[0086] Step 4 is replaced by: encapsulating the obtained decanoic acid / expanded vermiculite phase change material with epoxy resin to obtain encapsulated phase change material. Furthermore, the encapsulated phase change material replaces the disc-shaped shaped phase change material in subsequent steps.

[0087] The phase change thermal storage foam concrete prepared in this comparative example was tested as follows:

[0088] According to the dry density test conducted in accordance with JG / T 266-2011 "Foamed Concrete", the dry density of the phase change thermal storage foamed concrete prepared by the above method is 830 kg / m³. 3 .

[0089] The compressive strength of the phase change thermal storage foam concrete prepared by the above method was 4.4 MPa after 28 days, according to the compressive strength test of "Foamed Concrete" JG / T 266-2011.

[0090] The thermal conductivity of the phase change thermal storage concrete was tested according to the standard JG / T 266-2011 "Foamed Concrete". The thermal conductivity of the concrete was measured to be 0.249 W / (m·K) using a concrete thermal conductivity instrument.

[0091] Analysis of Example 1 and Comparative Example 1 shows that the concrete compressive strength decreases significantly after the phase change material is encapsulated with epoxy resin. This is because the outer layer of organic matter covering the phase change material creates a weak interface between the material and the phase change thermal storage foam concrete slurry. During the concrete compression process, cracks easily propagate from this point, leading to a decrease in the concrete compressive strength.

[0092] Comparative Example 2

[0093] The difference between this comparative example and Example 1 is that:

[0094] In step 4, a circular sheet-shaped phase change material with a diameter of 5 mm and a thickness of 1 mm is obtained.

[0095] The test results of the phase change thermal storage foam concrete prepared in this comparative example are as follows:

[0096] According to the dry density test conducted in accordance with JG / T 266-2011 "Foamed Concrete", the dry density of the phase change thermal storage foamed concrete prepared by the above method is 820 kg / m3.

[0097] The compressive strength of the phase change thermal storage foam concrete prepared by the above method was 5.3 MPa after 28 days, according to the compressive strength test of "Foamed Concrete" JG / T 266-2011.

[0098] The thermal conductivity of the phase change thermal storage concrete was tested according to the standard JG / T 266-2011 "Foamed Concrete". The thermal conductivity of the concrete was measured to be 0.191 W / (m·K) using a concrete thermal conductivity instrument.

[0099] Analysis of Example 1 and Comparative Example 2 shows that when the diameter and thickness of the disc-shaped shaped phase change material are too small, the thermal conductivity of the phase change thermal storage foam concrete is not significantly affected, but the compressive strength is significantly reduced. This is because the porous matrix material has a large specific surface area, so more slurry needs to be wrapped, resulting in a decrease in the workability of the concrete. In addition, if the disc is too small, the risk of leakage of the internal phase change agent increases.

[0100] Comparative Example 3

[0101] The difference between this comparative example and Example 1 is that:

[0102] In step 5, the added hydroxypropyl methylcellulose has a viscosity of 70,000.

[0103] Test results of the phase change thermal storage foam concrete prepared in this comparative example:

[0104] According to the dry density test conducted in accordance with JG / T 266-2011 "Foamed Concrete", the dry density of the phase change thermal storage foamed concrete prepared by the above method is 818 kg / m³. 3 .

[0105] The compressive strength of the phase change thermal storage foam concrete prepared by the above method was 4.6 MPa after 28 days, according to the compressive strength test of "Foamed Concrete" JG / T 266-2011.

[0106] The thermal conductivity of the phase change thermal storage concrete was tested according to the standard JG / T 266-2011 "Foamed Concrete". The thermal conductivity of the concrete was measured to be 0.260 W / (m·K) using a concrete thermal conductivity instrument.

[0107] Analysis of Example 1 and Comparative Example 3 shows that adding hydroxypropyl methylcellulose with a viscosity of 100,000 as a thickener to adjust the viscosity of the slurry prevents the disc-shaped shaped phase change material from floating and can also improve the stability of the foam in the slurry to a certain extent. When its viscosity is low (70,000), the compressive strength of the prepared phase change thermal storage foam concrete decreases significantly and the thermal conductivity increases accordingly. This is due to the disc-shaped shaped phase change material floating and unevenly distributed during the mixing process.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat-storing foamed concrete, characterized in that, It is made from a composition of the following raw materials in parts by weight: 450-900 parts cement, 200-400 parts auxiliary cementitious material, 50-100 parts phase change material, 150-300 parts water, 2-4 parts water-reducing agent, 0.1-0.2 parts thickener, 4-6 parts plant fiber and 12-28 parts foam; The phase change material is in sheet form, wherein each part by weight of the phase change material includes, by weight: 170-240 parts of porous matrix material and 85-170 parts of phase change agent adsorbed inside the porous matrix material. The porous matrix material is expanded vermiculite, and the sheet-like phase change material is formed by pressing the porous matrix material adsorbed with phase change agent.

2. The heat-storing foamed concrete as described in claim 1, characterized in that, The sheet-like phase change material has an equivalent diameter of 8-12 mm and a thickness of 3-4 mm. The phase change agent is at least one of fatty acids, alkanes, polyols, alcohols, and esters.

3. The heat-storing foamed concrete as described in claim 1, characterized in that, The cement is silicate cement; The auxiliary cementing material is silica fume with a SiO2 content greater than 90%; The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate greater than 25%; The thickener is hydroxypropyl methylcellulose with a viscosity of 80,000-100,000. The plant fiber is coconut shell fiber with a length of 15-17mm and an aspect ratio of 38-40.

4. The heat-storing foamed concrete as described in claim 1 or 2, characterized in that, The porous matrix material is modified expanded vermiculite with a particle size of 30-300 μm; the phase change agent is decanoic acid.

5. The heat-storing foamed concrete as described in claim 1, characterized in that, The foam is nanofoam with a density of 25-40 kg / m³. 3 .

6. The method for preparing thermal storage foamed concrete according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Pretreatment of porous matrix material: Modify the porous matrix material, and then heat it to expand it to obtain a modified expanded porous matrix material. S2. Adsorption of phase change agent: The phase change agent is dissolved in an organic solvent to prepare a phase change agent / organic solvent mixture, and then a modified expanded porous matrix material is added. The mixture is vacuum impregnated for 1-5 hours and then dried to obtain a modified expanded porous matrix material adsorbed with the phase change agent. S3. Phase change material compression molding: The modified expanded porous matrix material adsorbed with phase change agent is continuously compressed under a pressure of 4-6 MPa to obtain sheet-like phase change material. S4. Slurry preparation: First, mix cement, auxiliary cementitious materials and flaky phase change materials evenly, then add water, water-reducing agent and thickener and mix evenly to obtain slurry. S5. Preparation of thermal storage foam concrete: Add alkali-treated plant fibers to the slurry and mix well, then add foam and mix well, pour into a mold and cure to obtain thermal storage foam concrete.

7. The method for preparing thermal storage foamed concrete as described in claim 6, characterized in that, In S1, the process of modifying the porous matrix material is as follows: the porous matrix material is placed in an inorganic salt solution, stirred for 1-2 hours, and then filtered to obtain the modified porous matrix material. The heating and expansion process involves heating and expanding the modified porous matrix material at 700-800℃.

8. The method for preparing thermal storage foamed concrete as described in claim 6, characterized in that, In S2, the organic solvent is ethanol; the drying conditions are: drying at 20-30℃. In S5, the curing process is as follows: curing for 6-8 days at a temperature of 20-25℃ and a relative humidity of 85-90%.

9. The method for preparing thermal storage foamed concrete as described in claim 6, characterized in that, In S3, the modified expanded porous matrix material adsorbed with phase change agent is subjected to a pressure of 4 MPa for 1.5 min to obtain a sheet-like phase change material with an equivalent diameter of 10 mm.

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