Dual-encapsulation type phase change concrete with dynamic heat regulation and control function and preparation method of dual-encapsulation type phase change concrete

Abstract

The invention discloses dual-encapsulation type phase change concrete with a dynamic heat regulation and control function and a preparation method of the dual-encapsulation type phase change concrete, and belongs to the technical field of building materials. A dual-packaging structure of internal adsorption and external fixation and sealing is adopted, firstly, an n-tridecane / n-pentadecane eutectic mixture is loaded in a porous diatomite matrix, and then secondary packaging is performed through cement powder, so that the thermochemical stability of a phase change material is maintained, and the technical problems that traditional phase change concrete is easy to leak and poor in durability are effectively solved. The preparation method is simple in process, low in cost and environment-friendly and economical, the shaped composite diatomite-based phase change aggregate is added into the concrete, so that the concrete has excellent low-temperature heat regulation and control performance, freeze-thaw cycle damage can be remarkably relieved, the durability of the concrete is improved, meanwhile, the heat conductivity coefficient is reduced, the specific heat capacity is improved, and heat can be effectively stored / released. The system is particularly suitable for scenes such as cold region buildings and cold-chain logistics, heating energy consumption can be reduced, and an innovative solution is provided for green building development and double-carbon target implementation.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and in particular to a dual-encapsulated phase change concrete with dynamic thermal regulation function and its preparation method. Background Technology

[0002] With the continuous growth of global energy consumption and the increasing demand for building energy conservation, the development of building materials with efficient thermal regulation functions has become a research hotspot. Traditional ordinary concrete struggles to achieve dynamic temperature regulation under extreme climatic conditions, leading to increased building energy consumption, especially in cold regions where indoor and outdoor heat loss is more pronounced at low temperatures. To address this issue, incorporating phase change materials (PCMs) as a temperature control method has gradually become an effective way to improve the freeze-thaw resistance of concrete in recent years. PCMs possess the characteristic of absorbing or releasing latent heat within a specific temperature range, effectively buffering internal temperature fluctuations in concrete during solid-liquid phase transitions and reducing thermal stress caused by external temperature differences, thereby significantly mitigating the damage to concrete structures caused by freeze-thaw cycles. This temperature regulation mechanism not only improves the freeze-thaw resistance and temperature adaptability of concrete but also significantly enhances its long-term service durability, making it particularly suitable for infrastructure construction in cold regions and possessing promising engineering application prospects.

[0003] However, traditional phase change materials are mostly organic fatty acids or alkanes, which are prone to leakage, migration, and chemical decomposition in their liquid state. Directly incorporating them into concrete can lead to material loss, decreased structural mechanical properties, and reduced thermal control effectiveness. Therefore, effective encapsulation of phase change materials is necessary to improve their thermal stability, chemical inertness, and mechanical adaptability. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a dual-encapsulated phase change concrete with dynamic thermal regulation and its preparation method. It employs an "internal adsorption-external sealing" dual-encapsulation structure: First, a eutectic mixture of n-tetane / n-pentadecane with a phase change temperature of -10℃ to 0℃ is loaded into a porous diatomaceous earth matrix using vacuum adsorption to form diatomaceous earth-based phase change aggregate. Then, it is further encapsulated using cement slurry to obtain a shaped composite diatomaceous earth-based phase change aggregate. This aggregate exhibits excellent low-temperature thermal regulation performance, effectively mitigating freeze-thaw cycle damage and improving concrete durability; simultaneously, it reduces thermal conductivity and increases specific heat capacity, possessing good heat storage and release capabilities. This invention is particularly suitable for cold-region buildings and cold chain logistics, reducing heating energy consumption and providing technical support for green building development and achieving "dual-carbon" goals.

[0005] To achieve this technical objective, the present invention adopts the following solution: In a first aspect, the present invention provides a dual-encapsulated phase change concrete with dynamic thermal regulation function, comprising the following raw materials: shaped composite diatomaceous earth-based phase change aggregate, cement, coarse aggregate, fine aggregate, polycarboxylate superplasticizer and water; The shaped composite diatomaceous earth-based phase change aggregate is prepared by the following method: S1. Pretreatment of diatomaceous earth: The diatomaceous earth aggregate is dried and pretreated. S2. Preparation of composite phase change material: Mix n-tetane aggregate and n-pentadecane aggregate, stir evenly to obtain composite phase change material; S3. Vacuum adsorption: Add composite phase change material to the dried diatomite, and then perform vacuum adsorption to obtain diatomite-based phase change aggregate. S4. Re-encapsulation: Wet the surface of the diatomaceous earth-based phase change aggregate with water, evenly sprinkle an appropriate amount of cement powder, and stir thoroughly to make the surface of the diatomaceous earth-based phase change aggregate evenly coated with cement; cure it at 20 ℃ for 24 hours, and then put it in clean water for another 24 hours to form a dense and hard cement encapsulation layer on its surface, thus obtaining the shaped composite diatomaceous earth-based phase change aggregate.

[0006] Furthermore, by mass parts, the composition of the shaped composite diatomaceous earth-based phase change aggregate is: 106.36~319.08 parts; cement: 488.89 parts; coarse aggregate: 744.52~1116.13 parts; fine aggregate: 574.98 parts; polycarboxylate superplasticizer: 4.89 parts; and water: 220 parts.

[0007] Furthermore, the specific method for diatomaceous earth pretreatment is as follows: the diatomaceous earth aggregate is placed at a constant temperature of 60 ℃ and dried for 6 hours to fully remove residual moisture from the aggregate and avoid adverse effects on the adsorption of phase change materials.

[0008] Furthermore, the molar ratio of n-tetane aggregate to n-pentadecanane aggregate is 80:20.

[0009] Furthermore, the vacuum adsorption pressure was 0.089 MPa, the temperature was 40 ℃~80 ℃, and the time was 1 h~2 h to achieve full adsorption of the phase change material.

[0010] Furthermore, the cement is ordinary Portland cement.

[0011] Furthermore, the coarse aggregate is artificially crushed stone.

[0012] Furthermore, the fine aggregate is fine sand.

[0013] Secondly, the present invention provides a method for preparing the aforementioned dual-encapsulated phase change concrete with dynamic thermal regulation function, comprising the following steps: Step 1: Divide the water into two parts; Step 2, Dry mixing: The cement, coarse aggregate, fine aggregate, and shaped composite diatomaceous earth-based phase change aggregate are mixed for the first time; Step 3, Wet mixing: Add a portion of water for a second mixing; Step 4: Add the remaining water and polycarboxylate superplasticizer for a third mixing to obtain the mixed raw materials; Step 5: Fill the mixed raw materials into the test mold, place the test mold under the conditions of 20 ℃±2 ℃ and humidity of 95~99%, let it stand for one day, demold and shape, and cure under constant temperature and humidity for 28 days to obtain double-encapsulated phase change concrete with dynamic thermal regulation function.

[0014] Furthermore, by mass parts, the composition of the shaped composite diatomaceous earth-based phase change aggregate is: 106.36~319.08 parts; cement: 488.89 parts; coarse aggregate: 744.52~1116.13 parts; fine aggregate: 574.98 parts; polycarboxylate superplasticizer: 4.89 parts; and water: 220 parts.

[0015] Furthermore, in step three, add 140 parts water, and in step four, add 80 parts water.

[0016] Furthermore, the first mixing time is 30 seconds.

[0017] Furthermore, the second mixing time is 60 s.

[0018] Furthermore, the third mixing time is 60 s.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention uses a eutectic mixture of n-tetane and n-pentadecane in a molar ratio of 80:20 as a composite phase change core material, and diatomaceous earth as a porous carrier, prepared using vacuum adsorption technology. This results in a widened phase change temperature range, adaptable to building insulation requirements under different climatic conditions. Simultaneously, the selected alkane core material is non-toxic and chemically stable, and combined with the biodegradable properties of the diatomaceous earth carrier, it exhibits excellent environmental friendliness and meets the requirements of green building materials.

[0020] 2. The re-encapsulation technology used in this invention effectively reduces the leakage risk of phase change materials, while improving the structural strength, impermeability and thermal cycling stability of aggregates; it enhances the compatibility and dispersion uniformity of aggregates in the concrete matrix and reduces interface defects; it ensures the continuous stability of the thermal regulation function of materials under extreme temperature and freeze-thaw cycle conditions, thereby significantly extending the service life of building envelopes.

[0021] 3. The double-encapsulated shaped composite diatomaceous earth-based phase change aggregate prepared by the present invention has excellent temperature control performance. Its phase change temperature range is controlled between -10 ℃ and 0 ℃. It can effectively absorb and release heat in low temperature environment and is suitable for heat energy buffering and ambient temperature regulation under cold climate conditions.

[0022] 4. The technical solution of this invention adds self-shaped composite diatomaceous earth-based phase change aggregate and polycarboxylate superplasticizer to the dynamic thermal regulation dual-encapsulation phase change concrete, which endows the concrete with excellent dynamic thermal regulation capability and simultaneously improves the mechanical strength, impermeability and long-term thermal cycling stability of the aggregate, ensuring that the thermal regulation function remains effective under extreme conditions. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the preparation process of the phase change concrete of this invention.

[0024] Figure 2 This is a scanning electron microscope image of ordinary concrete according to the present invention.

[0025] Figure 3 This is a scanning electron microscope image of the phase change concrete of this invention.

[0026] Figure 4 This is an XRD pattern of the diatomaceous earth-based phase change aggregate and concrete of the present invention.

[0027] Figure 5 The images show the XRD patterns of phase change concrete with different proportions according to the present invention.

[0028] Figure 6 The images show the state of the different phase change energy storage concretes before and after crushing according to the present invention.

[0029] Figure 7 This is a diagram showing the compressive strength of the phase change energy storage concrete of this invention.

[0030] Figure 8 This is a diagram showing the specific heat capacity of ordinary concrete according to the present invention.

[0031] Figure 9 The specific heat capacity diagram of the phase change concrete incorporated with 10% of the present invention.

[0032] Figure 10 The specific heat capacity diagram of the phase change concrete incorporated in this invention (20%).

[0033] Figure 11 The specific heat capacity diagram of the phase change concrete incorporated in this invention (30%).

[0034] The markings in the attached diagram represent: 1. Shaped composite diatomaceous earth-based phase change aggregate. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0036] The core technology of this invention is the use of a shaped composite diatomaceous earth-cement dual-encapsulation phase change aggregate, combined with a polycarboxylate superplasticizer to optimize the process. Porous diatomaceous earth forms the inner shell, efficiently adsorbing and encapsulating the phase change material to prevent leakage, while simultaneously improving energy storage performance and structural durability. This phase change aggregate uses porous diatomaceous earth as the inner shell material, effectively adsorbing and encapsulating the phase change material to prevent leakage. Simultaneously, cement slurry coats the diatomaceous earth particles to form an outer shell layer, which solidifies through a hydration reaction at room temperature, forming a stable and dense protective layer. This further enhances the mechanical strength and thermal stability of the encapsulation structure, preventing the phase change material from escaping under high temperatures or external forces. Diatomaceous earth possesses advantages such as strong chemical stability, good compatibility with phase change materials, and low reactivity, and its porous structure provides excellent thermal buffering properties. The cement shell provides additional sealing and structural support, achieving a dual encapsulation mechanism of "internal adsorption and external solidification." Furthermore, both diatomaceous earth and cement are green and biodegradable materials, resulting in an overall environmentally friendly and non-toxic structure suitable for promotion and application in the field of green building. Example 1

[0037] This embodiment describes a dual-encapsulated phase change concrete with dynamic thermal regulation function and its preparation method, with the following specific steps: First, prepare shaped composite diatomaceous earth-based phase change aggregates according to the following steps.

[0038] S1. Pretreatment of diatomaceous earth: Place the diatomaceous earth aggregate in an oven at 60℃ and dry for 6 hours to fully remove its internal moisture. This pretreatment step effectively avoids the interference of residual moisture on the adsorption performance of phase change materials, ensuring the efficient encapsulation and stability of diatomaceous earth for phase change materials, thereby improving the overall performance of the shaped composite diatomaceous earth-based phase change aggregate.

[0039] S2. Preparation of composite phase change material: n-tetane and n-pentadecane eutectic is used as the phase change core material of the shaped composite diatomite-based phase change aggregate. n-tetane and n-pentadecane are mixed in a molar ratio of 80:20 and stirred evenly.

[0040] S3. Vacuum Adsorption: Diatomaceous earth-based phase change aggregate was prepared using vacuum adsorption. The dried diatomaceous earth aggregate was placed in a beaker, and a sufficient amount of the prepared n-tetane and n-pentadecane eutectic mixture was added. The beaker was then placed in a vacuum drying oven, and the oven was evacuated to 0.089 MPa using a vacuum pump. The vacuum drying oven was then turned on, and the adsorption temperature was adjusted to 60 °C. The adsorption time was controlled to be 1 h. After complete adsorption, diatomaceous earth-based phase change aggregate was obtained.

[0041] S4. Re-encapsulation: Complete encapsulation of the shaped composite diatomaceous earth-based phase change aggregate is achieved by re-encapsulating the diatomaceous earth-based phase change aggregate. First, the surface of the diatomaceous earth-based phase change aggregate is appropriately moistened to improve the adhesion of cement powder. Then, a predetermined amount of cement powder is evenly sprinkled onto its surface and thoroughly stirred to ensure the cement powder evenly coats the outer surface of the diatomaceous earth-based phase change aggregate. After coating, the aggregate is placed at room temperature (20 ℃) ​​for 24 hours to allow the cement to initially hydrate and solidify. Subsequently, the initially cured aggregate is placed in clean water for another 24 hours to ensure full cement hydration and the formation of a dense and hard cement shell on the aggregate surface, thus obtaining a structurally stable, well-encapsulated shaped composite diatomaceous earth-based phase change aggregate (denoted as G-PCM).

[0042] Then, a dual-encapsulated phase change concrete with dynamic thermal regulation function was prepared.

[0043] A dual-encapsulated phase change concrete with dynamic thermal regulation function comprises the following raw materials in parts by weight: 488.89 parts of ordinary Portland cement (PO42.4), 220 parts of water, 957.24 parts of artificial crushed stone, 574.98 parts of fine sand, 4.89 parts of polycarboxylate superplasticizer, and 106.36 parts of shaped composite diatomaceous earth-based phase change aggregate.

[0044] Mixing process: Add cement, artificial crushed stone, fine sand and shaped composite diatomaceous earth-based phase change aggregate to the mixer and dry mix for 30 seconds; add 140 parts water and continue mixing for 1 minute; add the remaining water and polycarboxylate superplasticizer and continue mixing for 1 minute.

[0045] Molding process: Pour the mixed raw materials into the mold, smooth it with a trowel and vibrate it to prevent aggregate settling; immediately cover the specimen with plastic film after molding, let it stand for 24 hours before demolding, check for defects before demolding, and discard it if there are any defects.

[0046] Curing process: Curing was carried out at a temperature of 20 ℃±2 ℃ and a relative humidity of 95 %~99%, with a spacing of 0.1 cm to 0.2 cm between specimens. After 28 days of curing, a double-encapsulated phase change concrete with dynamic thermal regulation function was obtained, denoted as APCM1. Example 2

[0047] This embodiment provides a dual-encapsulated phase change concrete with dynamic thermal regulation function and its preparation method.

[0048] The preparation method of the shaped composite diatomaceous earth-based phase change aggregate is the same as that in Example 1, and will not be repeated here.

[0049] A dual-encapsulated phase change concrete with dynamic thermal regulation function comprises the following raw materials in parts by weight: 488.89 parts cement, 220 parts water, 850.88 parts artificial crushed stone, 574.98 parts fine sand, 4.89 parts polycarboxylate superplasticizer, and 212.72 parts shaped composite diatomaceous earth-based phase change aggregate.

[0050] Mixing process: Add cement, artificial crushed stone, fine sand and shaped composite diatomaceous earth-based phase change aggregate to the mixer and dry mix for 30 seconds; add 140 parts water and continue mixing for 1 minute; add the remaining water and polycarboxylate superplasticizer and continue mixing for 1 minute.

[0051] Molding process: Pour the mixed raw materials into the mold, smooth it with a trowel and vibrate it to prevent aggregate settling; immediately cover the specimen with plastic film after molding and let it stand for 24 hours. Before demolding, check for defects. If there are defects, discard it.

[0052] Curing process: Curing was carried out at a temperature of 20 ℃±2 ℃ and a relative humidity of 95%~99%, with a spacing of 0.1 cm to 0.2 cm between specimens. After 28 days of curing, a double-encapsulated phase change concrete with dynamic thermal regulation function was obtained, denoted as APCM2. Example 3

[0053] This embodiment provides a dual-encapsulated phase change concrete with dynamic thermal regulation function and its preparation method.

[0054] The preparation method of the shaped composite diatomaceous earth-based phase change aggregate is the same as that in Example 1, and will not be repeated here.

[0055] A dual-encapsulated phase change concrete with dynamic thermal regulation function comprises the following raw materials in parts by weight: 488.89 parts cement, 220 parts water, 744.52 parts artificial crushed stone, 574.98 parts fine sand, 4.89 parts polycarboxylate superplasticizer, and 319.08 parts shaped composite diatomaceous earth-based phase change aggregate.

[0056] Mixing process: Add cement, artificial crushed stone, fine sand and shaped composite diatomaceous earth-based phase change aggregate to the mixer and dry mix for 30 seconds; add 140 parts water and continue mixing for 1 minute; add the remaining water and polycarboxylate superplasticizer and continue mixing for 1 minute.

[0057] Molding process: Pour the mixed raw materials into the mold, smooth it with a trowel and vibrate it to prevent aggregate settling; immediately cover the specimen with plastic film after molding and let it stand for 24 hours. Before demolding, check for defects. If there are defects, discard it.

[0058] Curing process: Curing was carried out at a temperature of 20 ℃±2 ℃ and a relative humidity of 95%~99%, with a spacing of 0.1 cm to 0.2 cm between specimens. After 28 days of curing, a double-encapsulated phase change concrete with dynamic thermal regulation function was obtained, denoted as APCM3. Comparative Example 1

[0059] This embodiment provides a type of concrete and its preparation method.

[0060] A type of concrete comprises the following raw materials in parts by weight: ordinary Portland cement (PO42.4): 488.89 parts; artificial crushed stone: 1116.13 parts; fine sand: 574.98 parts; polycarboxylate superplasticizer: 4.89 parts; water: 220 parts.

[0061] Mixing process: Add cement, artificial crushed stone, fine sand and shaped composite diatomaceous earth-based phase change aggregate to the mixer and dry mix for 30 seconds; add 140 parts water and continue mixing for 1 minute; add the remaining water and polycarboxylate superplasticizer and continue mixing for 1 minute.

[0062] Molding process: Pour the mixed raw materials into the mold, smooth it with a trowel and vibrate it to prevent aggregate settling; immediately cover the specimen with plastic film after molding and let it stand for 24 hours. Before demolding, check for defects. If there are defects, discard it.

[0063] Curing process: Curing was carried out at a temperature of 20 ℃±2 ℃ and a relative humidity of 95%~99%, with a spacing of 0.1 cm to 0.2 cm between specimens. After 28 days of curing, concrete was obtained, denoted as APCM0.

[0064] Regarding the mixing ratio of n-tetrazane and n-pentadecane, this specific ratio of mixture achieves the optimal phase transition enthalpy within the target temperature range. Based on this binary eutectic system, this invention focuses on compositing its encapsulation materials and studying its macroscopic performance and engineering application feasibility in concrete matrices.

[0065] The mass fractions of some raw materials in Examples 1-3 and Comparative Example 1 are shown in Table 1.

[0066] Table 1. Mass proportions of some raw materials in Examples 1-3 and Comparative Example 1 Performance testing and results analysis

[0067] The properties of the dual-encapsulated phase change concrete with dynamic thermal regulation function prepared in Examples 1-3 and the concrete prepared in Comparative Example 1 were tested respectively. The tests included scanning electron microscopy (SEM), XRD, compressive strength, thermal conductivity, and specific heat capacity. The test methods are as follows: SEM Test: A tungsten filament scanning electron microscope and a cold preparation system (Quanta450FEG) were used. Fragments from the compressive strength tests of phase change energy storage concrete at different ages were collected and placed in anhydrous ethanol to terminate cement hydration. The fragments were then used for SEM analysis. The phase change energy storage concrete fragments were fixed to the observation stage with special adhesive, and the samples were sprayed with gold. The fracture surface of the specimen under compressive stress was used as the observation surface.

[0068] XRD Test: A low-temperature X-ray diffraction system (model D8Advance) was used. During the test, fragments from the compressive strength test of phase change energy storage concrete were collected, placed in a covered container, and anhydrous ethanol was added to terminate hydration, resulting in XRD test samples of phase change energy storage concrete at different ages. The XRD test required grinding the phase change energy storage concrete fragments into powder and passing them through a 300-mesh square-hole sieve. Cu target radiation was used in the test, with a voltage of 45 kV, a current of 40 mA, a step size of 1 s, and an incident angle set to 2θ ranging from 5 ℃ to 90 ℃.

[0069] Compressive strength test: The compressive and flexural strength of ordinary and phase change energy storage concrete were determined in accordance with the "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081-2019). The compressive strength test was conducted using standard cubic specimens of 150 mm × 150 mm × 150 mm. Three cubic specimens were taken from each mix of concrete at 28 days of age for the test.

[0070] Thermal conductivity test: The transient heat source method was used, and the result was measured using a HotDisk instrument.

[0071] Specific heat capacity test: Differential scanning calorimeter, abbreviated as DSC. The test results are as follows:

[0072] (1) SEM (Scanning Electron Microscopy) The microstructures of APCM0 (control group) and APCM1 (10%) under operating conditions are as follows: Figure 2 and Figure 3 As shown. By Figure 2 and Figure 3 The comparison reveals a tight bond between the shaped composite diatomaceous earth-based phase change material and the concrete slurry, with the phase change material's outer shell maintaining its intact structure without significant damage. This is attributed to the high mechanical strength (compressive strength ≥15 MPa) of the diatomaceous earth carrier itself. This characteristic effectively overcomes the technical challenge of leakage inherent in traditional phase change materials in concrete environments, while ensuring the adaptability of the phase change material to volume changes during thermal cycling.

[0073] (2) XRD like Figure 4As shown, the addition of shaped composite diatomaceous earth-based phase change aggregate has no effect on the composition of ordinary concrete. This is mainly because the selected wall material is diatomaceous earth. Since the mineral composition of diatomaceous earth has good compatibility with cement, and its main component is amorphous or microcrystalline silicon dioxide, it is similar to the naturally occurring quartz component in concrete, thus not altering the concrete phase composition. The XRD patterns of phase change energy storage concrete with different proportions of shaped composite diatomaceous earth-based phase change aggregate are shown in the figures. Figure 5 As shown. Comparing the XRD patterns of schemes APCM0, APCM1, APCM2, and APCM3, it was found that the main phases in phase change energy storage concrete with different amounts of shaped composite diatomite-based phase change aggregate include quartz, calcium hydroxide, calcium hydrate zeolite, and calcium carbonate. Therefore, it can be determined that replacing the concrete with shaped composite diatomite-based phase change aggregate did not change the types of hydration products.

[0074] (3) Compressive strength The morphology of phase change energy storage concrete before and after uniaxial compressive failure was compared and analyzed. Figure 6 It was clearly observed that all four types of phase change concrete (APCM0, APCM1, APCM2, and APCM3) exhibited varying degrees of longitudinal cracking after compression. Among them, specimens APCM0, APCM1, and APCM2 showed some degree of surface spalling and significant deformation, indicating substantial structural damage during compression. In contrast, specimen APCM3 exhibited a denser crack distribution and higher degree of surface spalling, but its overall shape remained relatively intact, demonstrating a certain degree of structural stability. However, qualitative analysis based solely on morphological characteristics is insufficient to comprehensively assess the mechanical properties of phase change concrete; its compressive strength performance still requires quantitative verification through subsequent experimental data. Further testing and analysis will help reveal the failure mechanisms and performance differences of different types of phase change concrete under uniaxial compression.

[0075] Depend on Figure 7 It can be seen that the replacement amounts of the shaped composite diatomaceous earth-based phase change aggregate are 0%, 10%, 20%, and 30%, respectively. The compressive strength results of the phase change energy storage concrete at 28 days are as follows: Figure 7As shown in the figure, the strength of phase change concrete (PCC) decreases with the addition of shaped composite diatomaceous earth-based PCC aggregate. When the PCC aggregate replacement ratio is 10%, 20%, and 30%, the 28-day compressive strength of the PCC concrete is measured to be 38.33 MPa, 31.43 MPa, and 26.93 MPa, respectively. Compared with the baseline strength of ordinary concrete, these values ​​represent reductions of 26.9%, 40.11%, and 48.49%, respectively. This gradual decrease highlights the inverse relationship between PCC content and compressive strength. This strength reduction can be attributed to two main factors: the material properties of the shaped composite diatomaceous earth-based PCC aggregate and its interaction with the concrete matrix. First, the PCC used in this study is encapsulated in diatomaceous earth. Diatomaceous earth is a material with a highly porous microstructure. Adding diatomaceous earth to concrete introduces a large number of voids into the concrete matrix, thereby increasing its porosity. This increased porosity reduces the effective load-bearing cross-sectional area of ​​the concrete, thus weakening its ability to withstand compressive stress. Secondly, the mechanical strength of the phase change material itself is far lower than that of the basalt aggregate it partially replaces. Basalt is a strong and dense material that significantly contributes to the structural integrity of conventional concrete. In contrast, the softer phase change material particles are less able to resist compressive stress, which further exacerbates the reduction in the strength of phase change material concrete.

[0076] (4) Specific heat capacity from Figure 8 As can be seen from the curve, the specific heat capacity of ordinary concrete (APCM0) changes with temperature relatively flat, without obvious peaks, indicating that its thermal properties are mainly dominated by sensible heat processes and no phase change behavior occurs. Figure 9 , Figure 10 , Figure 11 As can be seen, the specific heat capacity curves of concrete samples (APCM1, APCM2, APCM3) incorporating shaped composite diatomaceous earth-based phase change aggregate exhibit similar trends with temperature: during the heating process, the specific heat capacity gradually increases, reaching a significant peak in a specific temperature range, and then begins to decrease. The peak specific heat capacity is due to the phase change of the shaped composite diatomaceous earth-based phase change aggregate in the concrete within this temperature range, resulting in a sharp increase in specific heat capacity due to the release or absorption of its latent heat. At this point, the specific heat capacity not only includes the sensible heat contribution of the material itself but also the latent heat of the phase change, forming the so-called equivalent specific heat capacity (i.e., APCM3 > APCM2 > APCM1). This indicates that the introduction of shaped composite diatomaceous earth-based phase change aggregate effectively enhances the heat storage capacity of concrete in the low-temperature region and strengthens its thermal buffering characteristics.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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. If these modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should be considered to be within the protection scope of the present invention.

Claims

1. A double-packing type phase change concrete having a dynamic thermal regulation function, characterized by, The raw materials include: shaped composite diatomite-based phase change aggregate, cement, coarse aggregate, fine aggregate, polycarboxylate superplasticizer and water; The shaped composite diatomite-based phase change aggregate is prepared by the following method: S1, pretreatment of diatomite: diatomite aggregate is dried and pretreated; S2, preparation of composite phase change material: n-tridecane aggregate and n-pentadecane aggregate are mixed and stirred uniformly to obtain the composite phase change material; S3, vacuum adsorption: the dried diatomite is added with the composite phase change material, and then vacuum adsorption is performed to obtain diatomite-based phase change aggregate; S4, re-encapsulation: the surface of the diatomite-based phase change aggregate is moistened with water, and an appropriate amount of cement powder is uniformly spread, and the diatomite-based phase change aggregate is fully stirred to make the surface of the diatomite-based phase change aggregate uniformly covered with cement; it is cured at 20 DEG C for 24 hours, and then placed in clean water for continuous curing for 24 hours, so that a dense and hard cement encapsulation layer is formed on the surface, and a shaped composite diatomite-based phase change aggregate is obtained.

2. The dual encapsulated phase change concrete with dynamic thermal regulation function according to claim 1, characterized in that, The shaped composite diatomite-based phase change aggregate is 106.36-319.08 parts by mass; the cement is 488.89 parts by mass; The coarse aggregate is 744.52-1116.13 parts by mass; the fine aggregate is 574.98 parts by mass; the polycarboxylate superplasticizer is 4.89 parts by mass; and the water is 220 parts by mass.

3. The dual encapsulated phase change concrete with dynamic thermal regulation function according to claim 1, characterized in that, The specific method for pretreating diatomite is to place it in a constant temperature oven at 60 DEG C for 6 hours to fully remove residual moisture in the aggregate.

4. The dual encapsulated phase change concrete with dynamic thermal regulation function according to claim 1, characterized in that, The molar ratio of n-tridecane aggregate to n-pentadecane aggregate is 80:

20.

5. The dual encapsulated phase change concrete with dynamic thermal regulation function according to claim 1, characterized in that, The pressure for vacuum adsorption is 0.089 MPa, the temperature is 40 DEG C-80 DEG C, and the time is 1 h-2 h to achieve full adsorption of the phase change material.

6. The dual encapsulated phase change concrete with dynamic thermal regulation function according to claim 1, characterized in that, The cement is ordinary Portland cement; and / or, the coarse aggregate is artificial crushed stone; and / or, the fine aggregate is fine sand.

7. A method of manufacturing a double-packed phase change concrete having a dynamic thermal regulation function according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: Step one, divide the water into two parts; Step two, dry mixing: the cement, coarse aggregate, fine aggregate and shaped composite diatomite-based phase change aggregate are mixed for the first time; Step three, wet mixing: a part of the water is added for the second mixing; Step four, the remaining water and polycarboxylate superplasticizer are added for the third mixing to obtain the mixed raw materials; Step five, the mixed raw materials are loaded into a test mold, the test mold is placed in a constant temperature and humidity environment of 20 DEG C±2 DEG C and 95-99% humidity for one day, and then demolded to form a double-encapsulated phase change concrete with dynamic thermal regulation function after curing for 28 days under constant temperature and humidity conditions.

8. The method of claim 7, wherein the method comprises the steps of: mixing the phase change material with the cement, the sand, the water, and the additives to form a mixture; and pouring the mixture into a mold to form the dual encapsulated phase change concrete. The shaped composite diatomite-based phase change aggregate is 106.36-319.08 parts by mass; the cement is 488.89 parts by mass; The coarse aggregate is 744.52-1116.13 parts by mass; the fine aggregate is 574.98 parts by mass; the polycarboxylate superplasticizer is 4.89 parts by mass; and the water is 220 parts by mass.

9. The method of claim 8, wherein the method comprises the steps of: mixing the phase change material with the cementitious material; and mixing the phase change material with the cementitious material and the thermal regulating material. 140 parts of water are added in step three, and 80 parts of water are added in step four.

10. The method of claim 7, wherein the method is characterized by the steps of: The time for the first mixing is 30 s; and / or, the time for the second mixing is 60 s; and / or, the time for the third mixing is 60 s.

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