Energy storage phase change concrete and preparation method thereof

Abstract

The invention discloses energy-storage phase-change concrete and a preparation method thereof, and relates to the technical field of building materials, the energy-storage phase-change concrete comprises the following raw materials: a cement base material, sand, aggregate, a water reducing agent and water; wherein the cement base material comprises cement, fly ash and rice hull ash, and the aggregate comprises phase change aggregate. The rice hull ash is added into a cement matrix material of the phase change concrete, and the interior of the rice hull ash has very high porosity and relatively high specific surface area, so that the rice hull ash has very good heat preservation and heat insulation performance. Therefore, after the phase change aggregate is introduced into the rice hull ash and fly ash doped cement matrix, the obtained rice hull ash-fly ash-phase change aggregate concrete can simultaneously utilize the latent heat of the phase change energy storage aggregate and the sensible heat of the rice hull ash-fly ash cement matrix to improve the heat insulation performance of the concrete in winter. Therefore, the energy storage phase change concrete provided by the invention can improve the heat insulation performance, so that the lowest indoor temperature in winter is improved, and the energy consumption related to heating is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to energy storage phase change concrete and a preparation method thereof. Background Art

[0002] As energy issues become increasingly prominent, energy conservation and improving energy efficiency are topics that need to be taken seriously. Globally, buildings consume about 40% of total energy consumption. A large part of the energy consumed by buildings is to adjust indoor temperature to improve thermal comfort. In order to maintain thermal comfort, HVAC consumes more than half of the total energy consumption. In winter, buildings located in cold areas need to consume huge amounts of energy to improve indoor comfort. The building materials of the external envelope structure have a great influence on the thermal insulation performance. Therefore, improving the thermal insulation performance of building materials can reduce energy consumption.

[0003] The thermal insulation performance of energy storage phase change concrete has attracted widespread attention at home and abroad. Phase change aggregate concrete can improve temperature damping, reduce the amplitude of temperature changes, and reduce energy demand due to the characteristics of phase change materials absorbing latent heat. Similarly, the latent heat released by phase change materials can reduce indoor temperature fluctuations in winter. Although phase change materials are added, the thermal properties of the cement matrix still affect the thermal properties of the concrete enclosure structure. Improving the thermal properties of the cement matrix and thus improving the thermal properties of concrete in combination with phase change aggregates is a meaningful topic. Summary of the invention

[0004] The main purpose of the invention is to provide an energy storage phase change concrete and a preparation method thereof, aiming to improve the thermal insulation performance of building materials.

[0005] To achieve the above object, the present invention provides an energy storage phase change concrete, which includes the following raw materials: cement base material, sand, aggregate, water reducing agent and water;

[0006] The cement matrix includes cement, fly ash and rice husk ash, and the aggregate includes phase change aggregate.

[0007] In one embodiment, the energy storage phase change concrete comprises the following raw materials, measured in parts by mass:

[0008] 380-440 parts of cement;

[0009] Rice husk ash 27.5-82.5 parts;

[0010] 55-82.5 parts of fly ash;

[0011] 620-660 parts of sand;

[0012] Aggregate 336-560 parts;

[0013] 5-6 parts of water reducing agent;

[0014] 176-192 parts of water.

[0015] In one embodiment, the phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate.

[0016] In one embodiment, in the phase change aggregate, the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is (2-5): (2-5): (2-5).

[0017] In one embodiment, the aggregate further comprises crushed stone.

[0018] The present invention also provides a method for preparing the energy storage phase change concrete as described above, comprising the following steps:

[0019] Divide the water into two parts;

[0020] Mix cement, rice husk ash and fly ash once;

[0021] Add the first part of water and water reducing agent for secondary mixing;

[0022] adding the phase change aggregate and the second portion of water and mixing for three times to obtain a mixed raw material;

[0023] The mixed raw materials are placed in a mold, and the mold is placed in a constant temperature and humidity chamber for curing to obtain energy storage phase change concrete.

[0024] In one embodiment, the time of the first mixing is 60 to 80 seconds.

[0025] In one embodiment, the secondary mixing time is 120 to 140 seconds.

[0026] In one embodiment, the time for the three mixing steps is 120 to 140 seconds.

[0027] In one embodiment, before the step of mixing cement, rice husk ash and fly ash, the following steps are also included:

[0028] The rice husk is burned at a temperature of 600-800°C and ground for 90-120 minutes to obtain rice husk ash.

[0029] In the technical solution provided by the present invention, rice husk ash is added to the cement material of the phase change concrete. The rice husk ash has a high porosity and a high specific surface area, so that the rice husk ash has good thermal insulation performance. However, the addition of rice husk ash reduces the working performance of concrete, so the present application introduces fly ash to improve the working performance of concrete. Therefore, the cement matrix doped with rice husk ash and fly ash in the present application, after the phase change aggregate is introduced, the obtained rice husk ash-fly ash-phase change aggregate concrete can simultaneously utilize the latent heat of the phase change energy storage aggregate and the sensible heat of the rice husk ash-fly ash cement matrix to improve the winter thermal insulation performance of the concrete. Therefore, the energy storage phase change concrete provided by the present invention can improve the thermal insulation performance, thereby increasing the minimum indoor temperature in winter and reducing the energy consumption related to heating. DETAILED DESCRIPTION

[0030] To make the purpose, technical scheme and advantages of the embodiment of the present invention clearer, the technical scheme in the embodiment of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiment, it is carried out according to the normal conditions or the conditions recommended by the manufacturer. If the reagents or instruments used do not specify the manufacturer, they are all conventional products that can be purchased commercially. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes, taking "A and / or B" as an example, including scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, the technical schemes between the various embodiments can be combined with each other, but must be based on the ability of ordinary technicians in the field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that the combination of such technical solutions does not exist, and is not within the scope of protection required by the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present invention.

[0031] As energy issues become increasingly prominent, energy conservation and improving energy efficiency are topics that need to be taken seriously. Globally, buildings consume about 40% of total energy consumption. A large part of the energy consumed by buildings is to adjust indoor temperature to improve thermal comfort. In order to maintain thermal comfort, HVAC consumes more than half of the total energy consumption. In winter, buildings located in cold areas need to consume huge amounts of energy to improve indoor comfort. The building materials of the external envelope structure have a great influence on the thermal insulation performance. Therefore, improving the thermal insulation performance of building materials can reduce energy consumption.

[0032] The thermal insulation performance of energy storage phase change concrete has attracted widespread attention at home and abroad. Phase change aggregate concrete can improve temperature damping, reduce the amplitude of temperature changes, and reduce energy demand due to the characteristics of phase change materials absorbing latent heat. Similarly, the latent heat released by phase change materials can reduce indoor temperature fluctuations in winter. Although phase change materials are added, the thermal properties of the cement matrix still affect the thermal properties of the concrete enclosure structure. Improving the thermal properties of the cement matrix and thus improving the thermal properties of concrete in combination with phase change aggregates is a meaningful topic.

[0033] In view of this, the present invention proposes an energy storage phase change concrete and a preparation method thereof, which can improve the thermal insulation performance of the phase change concrete, thereby increasing the minimum indoor temperature in winter and reducing energy consumption related to heating.

[0034] The energy storage phase change concrete provided by the present invention comprises the following raw materials: cement base material, sand, aggregate, water reducing agent and water; wherein the cement base material comprises cement, fly ash and rice husk ash, and the aggregate comprises phase change aggregate.

[0035] In the technical solution provided by the present invention, rice husk ash is added to the cement matrix material of the phase change concrete. The rice husk ash has a high porosity and a high specific surface area, so that the rice husk ash has good thermal insulation performance. However, the addition of rice husk ash reduces the working performance of concrete, so the present application introduces fly ash to improve the working performance of concrete. Therefore, the cement matrix doped with rice husk ash and fly ash in the present application, after the phase change aggregate is introduced, the obtained rice husk ash-fly ash-phase change aggregate concrete can simultaneously utilize the latent heat of the phase change energy storage aggregate and the sensible heat of the rice husk ash-fly ash cement matrix to improve the winter thermal insulation performance of the concrete. Therefore, the energy storage phase change concrete provided by the present invention can improve the thermal insulation performance, thereby increasing the indoor temperature in winter and reducing the energy consumption related to heating.

[0036] Furthermore, the following raw materials are included in parts by mass: 380-440 parts of cement; 27.5-82.5 parts of rice husk ash; 55-82.5 parts of fly ash; 620-660 parts of sand; 336-560 parts of aggregate; 5-6 parts of water reducer; 176-192 parts of water. The use of the above raw materials in parts by mass can better improve the thermal insulation performance. Preferably, 385 parts of cement, 82.5 parts of rice husk ash, 82.5 parts of fly ash, 652 parts of sand, 560 parts of aggregate, 5.5 parts of water reducer and 176 parts of water are used as raw materials to obtain energy storage phase change concrete with better thermal insulation performance.

[0037] It should be noted that in the present application, the particle size of the rice husk ash is 70 μm to 75 μm, the particle size of the cement is 25 μm to 30 μm, and the particle size of the fly ash is 10 μm to 15 μm. When rice husk ash and fly ash are added to concrete materials as cement matrix materials to replace part of the cement, the different particle sizes of cement, fly ash and rice husk ash are beneficial to improving the pore system of concrete and increasing the density.

[0038] Rice husk is the main byproduct of rice production and processing. However, rice husk is an agricultural waste with little nutrition and lacks economic value. At present, the most commonly used disposal method is open-air burning, which has an adverse effect on the air environment. Another treatment method is to deposit it in the soil. These rice husks take about five years to decompose and release a large amount of methane. In recent years, many power plants have begun to use rice husks as biomass fuels for power generation and heating. However, if the rice husk ash after burning is not treated, it may pollute natural resources such as water and soil, and occupy a large amount of land resources. Therefore, using rice husk ash as a substitute for cement material can promote the progress of green building materials. Rice husk ash has a high porosity inside and a high specific surface area. Therefore, the present application uses rice husk ash as one of the raw materials of phase change concrete to make the concrete have good thermal insulation properties. However, the addition of rice husk ash reduces the working performance of concrete, so fly ash is introduced to improve its working performance. Therefore, the addition amount of rice husk ash and fly ash affects the performance of concrete. As the mass fraction of rice husk ash increases, the compressive strength and thermal insulation properties of the obtained phase change concrete are gradually improved. However, when the mass fraction of rice husk ash is too high, although the thermal insulation performance will still be improved, the compressive strength of the concrete will be reduced. Therefore, when the mass fraction of the rice husk ash is within the above range, a phase change concrete with both compressive strength and thermal insulation properties can be obtained.

[0039] Fly ash can play an active role in concrete, undergoing secondary hydration reaction with cement hydration products to generate more hydration products, making the gap between cement and fly ash smaller, thereby improving the density and strength of concrete; fly ash can fill the micropores and gaps in concrete, increase the structural density, and improve the microstructure of concrete. If the amount of fly ash added is too much, the compressive strength of concrete will be reduced. Therefore, when the mass fraction of the fly ash is within the above range, a phase change concrete with better compressive strength can be obtained.

[0040] The mass proportion of the rice husk ash and the mass proportion of the fly ash can be set separately or simultaneously, and the present invention does not limit this. When they are set simultaneously, the obtained phase change concrete can have higher compressive strength and better thermal insulation performance. Preferably, when the mass proportion of the rice husk ash in the cement base material is 10% and the mass proportion of the fly ash is 15%, the obtained phase change concrete can have higher compressive strength and good thermal insulation performance.

[0041] It should be noted that the aggregate may also include crushed stone, the high hardness and crystallization mode of crushed stone enable it to withstand various stresses in concrete, thereby improving the overall strength of concrete, and crushed stone can effectively fill the voids in concrete, reduce the porosity of concrete, thereby improving the compactness and strength of concrete, so crushed stone can improve the mechanical properties of concrete, such as compressive strength and tensile strength. In addition, the pore structure of crushed stone can absorb and withstand a part of the freeze-thaw stress, improve the freeze-thaw resistance of concrete, and the crushed stone fills the voids of concrete, reducing the destructive force generated when water freezes, thereby protecting the stability and durability of the concrete structure. However, the thermal insulation effect of crushed stone is poor, so in some embodiments of the present application, phase change aggregate is used to replace the crushed stone in the aggregate, which can not only make concrete have better mechanical properties, but also improve the thermal insulation performance of concrete. Preferably, when the aggregate is composed of the phase change aggregate, the obtained phase change concrete can have better thermal insulation performance.

[0042] The phase change aggregate refers to an aggregate that can achieve phase transition within a certain temperature range, such as solid to liquid or liquid to solid, and they can undergo phase change when absorbing or releasing heat. Among them, paraffin phase change aggregate has a higher latent heat of phase change, and can absorb or release a large amount of heat during the phase change process; paraffin phase change aggregate also has good chemical stability and is not easy to react chemically with other substances. At the same time, it is non-toxic and non-corrosive, has good compatibility with metal containers and other equipment, and can be safely used in various occasions; paraffin phase change aggregate has no supercooling and precipitation phenomenon during the phase change process, which ensures the stability and reliability of its performance; the phase change process of paraffin phase change aggregate is solid-liquid phase change, which is easy to operate and control.

[0043] In addition, the melting point of the paraffin phase change aggregate can be adjusted according to different types of paraffin. Therefore, in some embodiments of the present application, the phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate. The phase change temperature of dodecane aggregate is -12.8°C, the phase change temperature of tridecane aggregate is -7.8°C, and the phase change temperature of tetradecane aggregate is 4.3°C. Dodecane aggregate, tridecane aggregate and tetradecane aggregate have different phase change temperatures. The use of a mixture of the three can enhance the adaptability of the phase change aggregate to changes in external temperature. In the process of temperature drop, tetradecane aggregate, tridecane aggregate and dodecane aggregate will release latent heat in turn, thereby increasing the minimum temperature, so as to meet the winter temperature of major cities in northwest China.

[0044] Furthermore, in the phase change aggregate, the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is (2-5): (2-5): (2-5). Specifically, the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate can be 4:3:3, 5:2:3, 3:5:2, 2:3:5, etc. Within the above range, a phase change concrete with better compressive strength can be obtained.

[0045] In phase change concrete, sensible heat performance is mainly used to adjust the temperature fluctuation of concrete, while latent heat performance is achieved through the phase change process of phase change materials to achieve more efficient energy storage and release, thereby improving the energy regulation efficiency of concrete. In this application, the sensible heat performance of concrete can be improved by adding rice husk ash, while the latent heat performance of concrete can be improved by using the above-mentioned phase change aggregate, thereby jointly improving the thermal insulation performance of concrete.

[0046] The present invention also provides a method for preparing the energy storage phase change concrete as described above, and the method for preparing the energy storage phase change concrete comprises the following steps:

[0047] Divide the water into two parts; the volume ratio of the first part of water to the second part of water can be 2:1 to 1:2, preferably, the volume ratio of the first part of water to the second part of water is 1:1.

[0048] The cement, rice husk ash and fly ash are mixed once; it should be noted that when crushed stone is added, the cement, rice husk ash, fly ash and crushed stone are mixed once. The time of the once mixing is 60 to 80 seconds, and the purpose of the once mixing is to mix the cement matrix.

[0049] Add the first part of water and water reducer for secondary mixing; the time of the secondary mixing is 120 to 140 seconds, and the purpose of the secondary mixing is to mix water with cement, rice husk ash and fly ash evenly. Among them, the water reducer has adsorption and dispersion effects, so that the surface of cement particles carries the same charge, and the repulsive force separates the cement particles, releasing flocculation structure free ions, increasing the fluidity of the concrete. Therefore, the addition of water reducer can reduce the amount of mixing water without affecting the slump of concrete, thereby improving the workability and performance of concrete. Specifically, in some embodiments, a polycarboxylic acid-based high-performance water reducer can be used.

[0050] Phase change aggregate and the second part of water are added and mixed three times to obtain a mixed raw material; the time for the three mixings is 120 to 140 seconds, and the purpose of the three mixings is to mix all the raw materials to obtain a mixed raw material.

[0051] The mixed raw materials are placed in a mold, and the mold is placed in a constant temperature and humidity chamber for curing to obtain energy storage phase change concrete.

[0052] Before the step of mixing cement, rice husk ash and fly ash, the method further includes preparing rice husk ash, which includes the following steps: burning rice husk at a temperature of 600-800° C. and grinding for 90-120 minutes to obtain rice husk ash.

[0053] Burning rice husks at a temperature range of 600-800°C can effectively decompose the organic matter in the rice husks and convert it into carbon. In this process, the organic components of the rice husks undergo high-temperature pyrolysis to generate solid residues with carbon as the main component, namely rice husk ash. The choice of burning temperature has an important influence on the properties of rice husk ash. Within the appropriate temperature range, a large amount of amorphous silica will be produced after burning rice husks, which will increase the volcanic ash effect of rice husk ash, thereby benefiting the strength of concrete.

[0054] The rice husk ash obtained after incineration needs to be ground to remove large particles and incompletely carbonized substances and improve its purity and uniformity. The grinding time of 90 to 120 minutes can ensure that the rice husk ash is fully refined and increase its surface area and reactivity. It should be noted that the average particle size of the ground rice husk ash can be 72.86 μm and the specific surface area can be 7697 cm 2 / g.

[0055] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention, and are not used to limit the present invention.

[0056] Example 1

[0057] Provided is an energy storage phase change concrete, the energy storage phase change concrete comprising the following raw materials in parts by mass: 440 parts of cement, 27.5 parts of rice husk ash, 82.5 parts of fly ash, 652 parts of sand, 560 parts of phase change aggregate, 5.5 parts of water reducer and 176 parts of water;

[0058] The phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate, and the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is 4:3:3.

[0059] Example 2

[0060] Provided is an energy storage phase change concrete, the energy storage phase change concrete comprising the following raw materials in parts by mass: 412.5 parts of cement, 55 parts of rice husk ash, 82.5 parts of fly ash, 652 parts of sand, 560 parts of phase change aggregate, 5.5 parts of water reducer and 176 parts of water;

[0061] The phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate, and the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is 4:3:3.

[0062] Example 3

[0063] Provided is an energy storage phase change concrete, the energy storage phase change concrete comprising the following raw materials in parts by mass: 385 parts of cement, 82.5 parts of rice husk ash, 82.5 parts of fly ash, 652 parts of sand, 560 parts of phase change aggregate, 5.5 parts of water reducer and 176 parts of water;

[0064] The phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate, and the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is 4:3:3.

[0065] Example 4

[0066] Provided is an energy storage phase change concrete, the energy storage phase change concrete comprising the following raw materials in parts by mass: 412.5 parts of cement, 55 parts of rice husk ash, 82.5 parts of fly ash, 620 parts of sand, 560 parts of phase change aggregate, 6 parts of water reducer and 182 parts of water;

[0067] The phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate, and the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is 4:3:3.

[0068] Example 5

[0069] Provided is an energy storage phase change concrete, the energy storage phase change concrete comprising the following raw materials in parts by mass: 412.5 parts of cement, 55 parts of rice husk ash, 82.5 parts of fly ash, 660 parts of sand, 560 parts of phase change aggregate, 5 parts of water reducer and 192 parts of water;

[0070] The phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate, and the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is 4:3:3.

[0071] Example 6

[0072] Provided is an energy storage phase change concrete, the energy storage phase change concrete comprising the following raw materials in parts by mass: 412.5 parts of cement, 55 parts of rice husk ash, 82.5 parts of fly ash, 652 parts of sand, 560 parts of phase change aggregate, 5.5 parts of water reducer and 176 parts of water;

[0073] The phase change aggregate only includes dodecane aggregate.

[0074] Example 7

[0075] Provided is an energy storage phase change concrete, the energy storage phase change concrete comprising the following raw materials in parts by mass: 412.5 parts of cement, 55 parts of rice husk ash, 82.5 parts of fly ash, 652 parts of sand, 560 parts of phase change aggregate, 5.5 parts of water reducer and 176 parts of water;

[0076] The phase change aggregate only includes tridecane aggregate.

[0077] Example 8

[0078] Provided is an energy storage phase change concrete, the energy storage phase change concrete comprising the following raw materials in parts by mass: 412.5 parts of cement, 55 parts of rice husk ash, 82.5 parts of fly ash, 652 parts of sand, 560 parts of phase change aggregate, 5.5 parts of water reducer and 176 parts of water;

[0079] The phase change aggregate only includes tetradecane aggregate.

[0080] The mass fractions of some raw materials of the energy storage phase change concrete provided in Examples 1 to 8 are shown in Table 1.

[0081] Table 1: Partial mass fractions of raw materials in Examples 1 to 8

[0082]

[0083]

[0084] Comparative Example 1

[0085] Provided is an energy storage phase change concrete, wherein the cement base material does not contain rice husk ash and the mass fraction of the cement base material is the same as that of Example 1, and other raw materials and mass fractions are the same as those of Example 1.

[0086] That is, the energy storage phase change concrete includes the following raw materials in parts by mass: 467.5 parts of cement, 82.5 parts of fly ash, 652 parts of sand, 560 parts of phase change aggregate, 5.5 parts of water reducer and 176 parts of water;

[0087] The cement base material includes cement and fly ash, and the mass ratio of cement to fly ash is 85:15;

[0088] The phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate, and the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is 4:3:3.

[0089] Comparative Example 2

[0090] Provided is an energy storage phase change concrete, wherein the cement base material does not contain rice husk ash and fly ash and the mass fraction of the cement base material is the same as that of Example 1, and other raw materials and mass fractions are the same as those of Example 1.

[0091] That is, the energy storage phase change concrete includes the following raw materials in parts by mass: 550 parts of cement, 652 parts of sand, 560 parts of phase change aggregate, 5.5 parts of water reducer and 176 parts of water;

[0092] The phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate, and the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is 4:3:3.

[0093] Comparative Example 3

[0094] Provided is an energy storage phase change concrete, wherein the raw materials do not contain phase change aggregate, and other raw materials and mass fractions are the same as those in Example 1.

[0095] Performance Testing

[0096] The performance of the energy storage phase change concrete prepared in the above-mentioned Examples 1 to 8 and Comparative Examples 1 to 3 was tested respectively, and the test items included compressive strength, thermal conductivity, thermal diffusion coefficient, and peak temperature. The test method is as follows:

[0097] Compressive strength: The compressive strength is tested according to GB / T 50081-2019 "Standard for Test Methods for Physical and Mechanical Properties of Concrete".

[0098] Thermal conductivity and thermal diffusivity: measured using a hotdisk instrument using the transient heat source method.

[0099] Temperature difference: obtained through temperature-time curve. The test is carried out in a temperature test chamber, and the minimum temperature is set to -18°C. A K-type thermocouple is placed in the concrete test block during pouring, and then the concrete test block is placed in the environmental chamber to obtain the curve of concrete internal temperature and time. The temperature difference is the maximum difference between the internal temperature of the concrete and the ambient temperature.

[0100] The test results are shown in Table 2.

[0101] Table 2 Test results of Examples 1 to 8 and Comparative Examples 1 to 3

[0102]

[0103] From the compressive strength data in Table 2, it can be seen that the strength of concrete increases after adding rice husk ash within a certain range. However, the strength of concrete with excessive rice husk ash decreases, which is 13.46% lower than that of the benchmark concrete. This may be due to the excessive amount of auxiliary cementitious materials replacing cement in concrete, which reduces the early hydration products and affects the formation of early strength of concrete. The reason for the decrease in strength is that as the amount of rice husk ash increases, the influence of replacing cement becomes greater. When the beneficial effect of rice husk ash on strength cannot offset the adverse effect of replacing cement on strength, the strength begins to decrease.

[0104] In the 28d strength, the maximum compressive strength of the concrete with rice husk ash added can reach 44.83MPa, which is 10.26% higher than that of the concrete without rice husk ash. When the amount of rice husk ash added is too large, the strength of the concrete decreases. After comparing the 7d strength and the 28d strength, it is found that with the addition of rice husk ash, the later strength growth is greater. This is because as the amount of rice husk ash added increases, the amorphous silica in the rice husk ash further undergoes hydration reaction with the hydration product, which increases the later strength of the concrete. Therefore, the sources of strength in concrete with rice husk ash can be divided into the compacting effect of rice husk ash and the volcanic ash effect.

[0105] The thermal performance of concrete is evaluated by thermal conductivity and thermal diffusivity. The thermal conductivity and thermal diffusivity of concrete directly affect the thermal conductivity. The lower the thermal conductivity and thermal diffusivity, the better the thermal insulation performance. It can be seen from the thermal conductivity data in Table 2 that as rice husk ash replaces cement, the thermal conductivity of concrete shows a downward trend. The more rice husk ash is added, the lower the thermal conductivity. The decrease in thermal conductivity after adding rice husk ash can be attributed to the large number of pores inside the rice husk ash, so rice husk ash has good thermal insulation properties. When rice husk ash replaces cement, the thermal conductivity of concrete decreases. Low thermal conductivity helps to improve the temperature damping and thermal insulation properties of concrete.

[0106] It can be seen from the temperature difference in Table 2 that the temperature difference of rice husk ash-fly ash-phase change aggregate concrete is larger, so the temperature drops more slowly in the same period of time. This is because the thermal response of concrete with added phase change aggregate is slower than that of ordinary concrete, and the phase change aggregate releases latent heat during the cooling process to offset the temperature drop of the concrete sample. In addition, the addition of composite phase change aggregate reduces the thermal conductivity of concrete, thereby changing the heat transfer during the cooling process. At the same time, the poor thermal conductivity of the rice husk ash-fly ash cement matrix also reduces the rate of temperature drop. It can be seen from the temperature difference data in Table 2 that the temperature of rice husk ash-fly ash-phase change aggregate concrete is 7.3℃-8℃ higher than the ambient temperature, showing good thermal insulation performance. Therefore, the energy storage phase change concrete provided by the present invention can improve the thermal insulation performance, thereby increasing the minimum indoor temperature in winter and reducing the energy consumption associated with heating.

[0107] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An energy storage phase change concrete, characterized in that: The energy storage phase change concrete comprises the following raw materials: Cementitious base material, sand, aggregate, water reducing agent and water; The cement matrix includes cement, fly ash and rice husk ash, and the aggregate includes phase change aggregate.

2. The energy storage phase change concrete according to claim 1, characterized in that: The energy storage phase change concrete comprises the following raw materials in parts by mass: 380-440 parts of cement; Rice husk ash 27.5-82.5 parts; 55-82.5 parts of fly ash; 620-660 parts of sand; Aggregate 336-560 parts; 5-6 parts of water reducing agent; 176-192 parts of water.

3. The energy storage phase change concrete according to claim 1, characterized in that: The phase change aggregate includes dodecane aggregate, tridecane aggregate and tetradecane aggregate.

4. The energy storage phase change concrete according to claim 3, characterized in that: In the phase change aggregate, the mass ratio of the dodecane aggregate, the tridecane aggregate and the tetradecane aggregate is (2-5): (2-5): (2-5).

5. The energy storage phase change concrete according to claim 1, characterized in that: The aggregate also includes crushed stone.

6. A method for preparing the energy storage phase change concrete according to any one of claims 1 to 5, characterized in that: The following steps are involved: Divide the water into two parts; Mix cement, rice husk ash and fly ash once; Add the first part of water and water reducing agent for secondary mixing; adding the phase change aggregate and the second portion of water and mixing for three times to obtain a mixed raw material; The mixed raw materials are placed in a mold, and the mold is placed in a constant temperature and humidity chamber for curing to obtain energy storage phase change concrete.

7. The method for preparing the energy storage phase change concrete according to claim 6, characterized in that: The time of the first mixing is 60 to 80 seconds.

8. The method for preparing the energy storage phase change concrete according to claim 6, characterized in that: The secondary mixing time is 120 to 140 seconds.

9. The method for preparing the energy storage phase change concrete according to claim 6, characterized in that: The time for the three mixings is 120 to 140 seconds.

10. The method for preparing the energy storage phase change concrete according to claim 6, characterized in that: Before the step of mixing cement, rice husk ash and fly ash, the method further comprises the following steps: The rice husk is burned at a temperature of 600-800°C and ground for 90-120 minutes to obtain rice husk ash.

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