Phase-change recycled aggregate, preparation method thereof and anti-freezing water-stable material

Abstract

The invention relates to the technical field of building materials, in particular to phase-change recycled aggregate, a preparation method thereof and an anti-freezing water-stable material. The phase-change recycled aggregate comprises a base material and a packaging layer coating the surface of the base material, the base material comprises a porous decoration waste aggregate structure and an organic phase-change material, and the organic phase-change material is located in gaps of the porous decoration waste aggregate structure; the porous decoration waste aggregate structure comprises aerated concrete aggregate; the encapsulation layer includes a first cementitious material. According to the invention, the phase-change material is used for infiltrating and filling holes in the surface of the aerated concrete aggregate, and then the cement paste is used for wrapping and packaging, so that the reinforcement of the recycled aggregate is completed, the water absorption of the recycled aggregate is reduced, the phase-change material is packaged in the aggregate, and the separation loss of the recycled aggregate is reduced; the high-temperature heat absorption and low-temperature heat release performances of the organic phase-change material are utilized to relieve the stress damage of temperature impact to the internal structure, so that the heat preservation period during winter construction can be prolonged, and the effective hydration time of the cement can be prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and more particularly, to a phase change recycled aggregate, a preparation method thereof, and an anti-freezing water-stable material. Background Art

[0002] Construction waste is mainly divided into building demolition waste mainly composed of brick-concrete materials and decoration waste mainly composed of aerated concrete insulation layers and ceramic tiles. At present, demolition waste has a relatively wide range of resource applications in recycled inorganic materials, recycled bricks, etc. Due to problems such as low strength, small density, and large water absorption of aerated concrete aggregates in decoration waste, its resource application scenarios are very limited. Since the water absorption rate of recycled aggregates is much greater than that of natural sand and gravel aggregates, their durability mainly in terms of long-term freeze-thaw performance is poor, seriously affecting their resource application.

[0003] Existing technical means for winter construction and anti-freezing of inorganic materials mainly involve adding anti-freezing agents (industrial salts, concrete anti-freezing agents, etc.). Their main function is to lower the dissolution temperature of the aqueous solution, thereby alleviating the ice stress damage of the water inside the structural layer. In the case of high dosages, it is extremely easy to cause salt freeze stress inside, resulting in excessive internal osmotic pressure, which not only damages the road structure but also causes environmental pollution in the long term. In addition, at low temperatures, although the freezing point is reduced, the hydration activity of cement also decreases with temperature, and its strength growth at low temperatures is not optimistic.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] An object of the present invention is to provide a phase change recycled aggregate to solve the technical problems of high water absorption rate and poor anti-freezing performance of existing phase change recycled aggregates. The phase change recycled aggregate of the present invention has a low water absorption rate, can improve the strength of porous decoration waste aggregates, and improve the anti-freezing performance.

[0006] Another object of the present invention is to provide a preparation method of the phase change recycled aggregate, and the method is simple and easy to implement.

[0007] Another object of the present invention is to provide an anti-freezing water-stable material, which can ensure a high compressive strength, excellent anti-freezing performance, and small loss of water-stable strength in a low-temperature environment.

[0008] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0009] A phase change recycled aggregate includes a matrix material and a packaging layer coated on the surface of the matrix material. The matrix material includes a porous decoration waste aggregate structure and an organic phase change material, and the organic phase change material is located in the voids of the porous decoration waste aggregate structure; the porous decoration waste aggregate structure includes aerated concrete aggregates; the packaging layer includes a first cement material.

[0010] In some embodiments, the thickness of the encapsulation layer is 0.5 to 2.0 mm.

[0011] In some embodiments, the particle size of the aerated concrete aggregate is 5 to 25 mm.

[0012] In some embodiments, the phase change temperature of the organic phase change material is -10 to 10 °C.

[0013] In some embodiments, the organic phase change material includes paraffin-based phase change materials.

[0014] In some embodiments, the paraffin-based phase change materials include tetradecane.

[0015] In some embodiments, the water absorption rate of the porous decoration waste aggregate structure is 15% to 25%.

[0016] In some embodiments, the water absorption rate of the phase change recycled aggregate is less than 10%.

[0017] In some embodiments, the first cementitious material includes ordinary Portland cement, early strength cement or quick-setting cement with a 28-day compressive strength greater than or equal to 42.5 MPa.

[0018] The preparation method of the phase change recycled aggregate as described above includes the following steps:

[0019] The aerated concrete aggregate is infiltrated with a liquid organic phase change material and then cooled and solidified to obtain a matrix material; the matrix material is wrapped with a slurry of the first cementitious material, and the phase change recycled aggregate is obtained after curing.

[0020] In some embodiments, the mass ratio of the porous decoration waste aggregate structure, the organic phase change material and the first cementitious material is (30 to 70):(5 to 10):(20 to 70).

[0021] In some embodiments, the phase change temperature of the organic phase change material is -10 to 10 °C, and it is cooled in an environment slightly lower than the phase change temperature.

[0022] In some embodiments, the time of the infiltration treatment is less than or equal to 5 min.

[0023] In some embodiments, vibration operation or vacuum operation is adopted during the infiltration treatment.

[0024] In some embodiments, the slurry is cement slurry, the water addition amount is 30% to 70%, and the water reducing agent is 0.2% to 1%.

[0025] An anti-freezing water-stable material, comprising the phase change recycled aggregate, brick-concrete aggregate and second cementitious material as described above; the mass content of the phase change recycled aggregate in the anti-freezing water-stable material is 10% - 20%.

[0026] An anti-freezing water-stable material, wherein the second cementitious material comprises blast furnace slag Portland cement with a 28-day compressive strength greater than or equal to 32.5 MPa or other retarder cements for road use.

[0027] In some embodiments, the mass content of the brick-concrete aggregate in the anti-freezing water-stable material is 70% - 85%; the mass content of the second cementitious material in the anti-freezing water-stable material is 4% - 7%.

[0028] The preparation method of the anti-freezing water-stable material as described above comprises the following steps:

[0029] Mix and process the phase change recycled aggregate, brick-concrete aggregate, appropriate amount of water and second cementitious material.

[0030] In some embodiments, the 7-day unconfined compressive strength of the anti-freezing water-stable material is 2.0 - 4.0 MPa.

[0031] In some embodiments, the 28-day freeze-thaw residual compressive strength ratio of the anti-freezing water-stable material is 95% - 97%.

[0032] In some embodiments, the loss of 7-day unconfined compressive strength of the anti-freezing water-stable material cured under the condition that the outdoor temperature in winter is -5 to 5 °C is 5% - 10%.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) For the phase change recycled aggregate of the present invention, aerated concrete aggregate in the decoration waste aggregate is adopted. The surface pores are infiltrated and filled with the phase change material, and at the same time, the aggregate is wrapped and encapsulated with cement slurry, so as to enhance the recycled aggregate and greatly reduce its water absorption rate. In addition, the phase change material is encapsulated in the aggregate, reducing its detachment loss. By utilizing the performance of the organic phase change material to absorb heat at high temperature and release heat at low temperature, the stress damage of the temperature impact on its internal structure is alleviated, the heat preservation period during winter construction can be extended, and the effective hydration time of cement can be prolonged.

[0035] (2) The present invention uses the organic phase change material in high-temperature liquid phase to infiltrate the aerated concrete aggregate, so that the phase change material fills the pores of the aerated concrete, and then cools and solidifies; then it is wrapped with the slurry of the first cementitious material to improve the strength of the aerated concrete aggregate and have an appropriate water absorption rate. Through the cooperation of each step, the obtained phase change recycled aggregate has a low water absorption rate, good strength under low temperature conditions, and can extend the effective hydration time of cement.

[0036] (3) The antifreeze water-stable material of the present invention has appropriate strength, a high residual compressive strength ratio after 28-day freeze-thaw cycles. By using phase change materials, it can effectively guarantee the hydration conditions of cement, promote the growth of water-stable strength under winter conditions, and has good antifreeze ability. In addition, using decoration waste aggregates to produce inorganic materials also increases the scenarios for the resource utilization of decoration waste aggregates at the present stage and solves the problem of their resource utilization outlets. Specific Embodiments

[0037] The following will describe the implementation schemes of the present invention in detail in conjunction with embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0038] According to one aspect of the present invention, the present invention relates to a phase change recycled aggregate, including a matrix material and a packaging layer coated on the surface of the matrix material. The matrix material includes a porous decoration waste aggregate structure and an organic phase change material, and the organic phase change material is located in the voids of the porous decoration waste aggregate structure; the porous decoration waste aggregate structure includes aerated concrete aggregates; the packaging layer includes a first cement material.

[0039] The present invention uses aerated concrete aggregates in decoration waste aggregates, infiltrates and fills the surface openings with phase change materials, and simultaneously wraps and encapsulates the aggregates with cement slurry. It not only enhances the recycled aggregate and greatly reduces its water absorption rate, but also encapsulates the phase change materials in the aggregates, reducing their detachment loss. By utilizing the properties of phase change materials to absorb heat at high temperatures and release heat at low temperatures, it alleviates the stress damage to its internal structure caused by temperature shock, extends the heat preservation period during winter construction, and prolongs the effective hydration time of cement.

[0040] In some embodiments, the thickness of the packaging layer is 0.5 - 2.0 mm, such as 0.5 mm, 1 mm, 1.5 mm, 2 mm, etc.

[0041] In some embodiments, the particle size range of the aerated concrete aggregates is 5 - 25 mm, such as 5 - 10 mm, 10 - 20 mm, 20 - 25 mm, 5 - 25 mm, etc.

[0042] In some embodiments, the phase change temperature of the organic phase change material is -10 - 10 °C.

[0043] In some embodiments, the organic phase change material includes paraffin-based phase change materials. In some embodiments, the paraffin-based phase change materials include tetradecane. For example, n-tetradecane paraffin, because its phase change temperature is 5.5 °C, can be used for road material construction near room temperature in autumn and winter.

[0044] In some embodiments, the water absorption rate of the porous decoration waste aggregate structure is 15% - 25%, such as 15%, 17%, 19%, 21%, 23%, 25%, etc., or the range value between any two of them.

[0045] In some embodiments, the water absorption rate of the phase change recycled aggregate is less than 10%, such as 5%, 6%, 7%, 8%, 9%, etc.

[0046] In some embodiments, the first cementitious material includes ordinary Portland cement or early strength / quick setting cement with a 28-day compressive strength greater than or equal to 42.5 MPa. For example, P.O 42.5 cement.

[0047] According to another aspect of the present invention, the present invention also relates to a preparation method of the phase change recycled aggregate as described above, including the following steps:

[0048] The aerated concrete aggregate is infiltrated with a liquid organic phase change material, and then cooled and solidified to obtain a matrix material. The matrix material is wrapped with a slurry of the first cementitious material, and the phase change recycled aggregate is obtained after curing.

[0049] The present invention infiltrates the aerated concrete aggregate with a high-temperature liquid organic phase change material, so that the phase change material fills the pores of the aerated concrete, and then cools and solidifies; then it is wrapped with a slurry of the first cementitious material. Through the cooperation of each step, the obtained phase change recycled aggregate has a low water absorption rate and the strength is improved to a certain extent.

[0050] In some embodiments, the mass ratio of the porous decoration waste aggregate structure, the organic phase change material and the first cementitious material is (30 - 70):(5 - 10):(20 - 70), such as 55:10:35, 70:10:20, 46:8:46, 30:5:65. The porous decoration waste aggregate structure, the organic phase change material and the first cementitious material of the present invention adopt appropriate mass ratios, which are more conducive to ensuring the low water absorption rate and high strength of the phase change recycled aggregate.

[0051] In some embodiments, the phase change temperature of the organic phase change material is -10 to 10 °C. Different types of paraffin are selected according to different application scenarios. The liquid phase is higher than this phase change temperature, and it is cooled in an environment slightly lower than the phase change temperature.

[0052] In some embodiments, the time of the infiltration treatment is less than or equal to 5 min, such as 2 min, 3 min, 4 min, 5 min, etc. An appropriate infiltration treatment time can ensure sufficient infiltration of the materials.

[0053] In some embodiments, vibration operation or vacuum / negative pressure operation is adopted during the infiltration treatment. The filling of the phase change material in the pores of the aerated concrete can be accelerated by vibration operation or vacuum / negative pressure operation.

[0054] In some embodiments, the temperature for cooling and solidifying is 0 - 5°C, such as 1°C, 2°C, 3°C, 4°C, etc.

[0055] In some embodiments, the slurry is cement slurry with a water content of 25% - 40%, and a water reducing agent of 0.2% - 1% can be admixed externally. Conventional water reducing agents can be used, such as polycarboxylate water reducing agents, naphthalene sulfonate water reducing agents, or lignosulfonate water reducing agents. Polycarboxylate superplasticizer is used in each embodiment of the present invention.

[0056] In some embodiments, the curing time is less than or equal to 28d, such as 2d, 3d, 7d, 14d, 28d, etc. The present invention adopts an appropriate curing time to ensure the mechanical properties of the phase change recycled aggregate.

[0057] An anti - freezing water - stable material includes the phase change recycled aggregate, brick - concrete aggregate, and a second cementitious material; the mass content of the phase change recycled aggregate in the anti - freezing water - stable material is 10% - 20%.

[0058] The anti - freezing water - stable material of the present invention has appropriate strength, a high 28 - day freeze - thaw residual compressive strength ratio. Using the phase change material can effectively guarantee the hydration conditions of cement, promote the growth of water - stable strength under winter conditions, and has good anti - freezing ability. In addition, using decoration waste aggregate for the production of inorganic materials also increases the scenarios of decoration waste aggregate resource utilization at the present stage and solves the problem of its resource utilization outlet.

[0059] In some embodiments, the mass content of the phase change recycled aggregate in the anti - freezing water - stable material is 10% - 20%, such as 10%, 12%, 15%, 18%, or 20%, etc.

[0060] In some embodiments, the mass content of the brick - concrete aggregate in the anti - freezing water - stable material is 70% - 85%, such as 70%, 72%, 75%, 78%, 80%, 85%, etc.

[0061] In some embodiments, the mass content of the second cementitious material in the anti - freezing water - stable material is 4% - 7%, such as 4%, 5%, 6%, 7%, etc.

[0062] An anti - freezing water - stable material, the second cementitious material includes slag Portland cement with a 28 - day compressive strength greater than or equal to 32.5MPa or other road - use retarder cements. For example, P.S.A32.5 cement.

[0063] In some embodiments, the 7-day unconfined compressive strength of the frost-resistant water-stable material is 2.0 - 4.0 MPa, such as 2.0 MPa, 2.5 MPa, 3.0 MPa, 3.5 MPa, 4.0 MPa, etc., which can meet the requirements of conventional road bases.

[0064] In some embodiments, the 28-day freeze-thaw residual compressive strength ratio of the frost-resistant water-stable material is 95% - 97%, such as 95%, 96% or 97%, etc., which is superior to conventional water-stable materials.

[0065] In some embodiments, the 7-day unconfined compressive strength of the frost-resistant water-stable material cured under the condition that the outdoor temperature in winter is -5 to 5 °C is 3.2 - 3.8 MPa, such as 3.2 MPa, 3.3 MPa, 3.5 MPa, 3.7 MPa, 3.8 MPa, etc. The strength loss is 5% - 10%, such as 5%, 5.5%, 5.8%, 6%, 7%, 8%, 8.5%, etc., which is much less than the strength loss of conventional water-stable materials during winter construction and curing.

[0066] The preparation method of the described frost-resistant water-stable material includes: mixing the phase change recycled aggregate, brick-concrete aggregate, appropriate amount of water and the second cementitious material. By mixing the phase change recycled aggregate, brick-concrete aggregate and the second cementitious material, a frost-resistant water-stable material with high frost resistance and water stability performance is obtained.

[0067] The following is further explained and illustrated in combination with specific examples and comparative examples.

[0068] Example 1

[0069] A preparation method of a phase change recycled aggregate includes the following steps:

[0070] (a) The aerated concrete aggregate is infiltrated with n-tetradecane. The particle size of the aerated concrete aggregate is 10 - 20 mm, the infiltration time is 5 min, vibration operation is adopted during the infiltration process, and then cooling and solidification are carried out. The temperature of cooling and solidification is 3 °C to obtain the matrix material.

[0071] (b) The matrix material is wrapped with the cement slurry of the first cementitious material (P.O 42.5) (the water content is 40% and the admixture content of the water reducer is 0.5%). The mass ratio of the aerated concrete aggregate: cement slurry: n-tetradecane is 70:20:10. After the cement slurry solidifies, it is cured under standard conditions for 7 days to obtain the phase change recycled aggregate.

[0072] Example 2

[0073] A preparation method of a phase change recycled aggregate, which is different from that of Example 1 in that:

[0074] The particle size of the aerated concrete aggregate is 5 - 10 mm, and the mass ratio of the aerated concrete aggregate: cement slurry: n - tetradecane is 55:35:10.

[0075] Example 3

[0076] A preparation method of phase - change recycled aggregate includes the following steps:

[0077] (a) The aerated concrete aggregate with a particle size of 10 - 20 mm is infiltrated with n - tetradecane. The infiltration time is 5 min, and vibration operation is adopted during the infiltration process. Then, cooling and solidification are carried out at a temperature of 3 °C to obtain the matrix material.

[0078] (b) The matrix material is wrapped with the cement slurry (water content is 30%, water - reducing agent dosage is 0.5%) of the first cement material (P.O 42.5). The mass ratio of the aerated concrete aggregate: cement slurry: n - tetradecane is 46:46:8. After the cement slurry solidifies, it is cured under standard conditions for 7 d to obtain the phase - change recycled aggregate.

[0079] Example 4

[0080] A preparation method of phase - change recycled aggregate, the difference from Example 1 is:

[0081] The particle size of the aerated concrete aggregate is 5 - 10 mm, and the mass ratio of the aerated concrete aggregate: cement slurry: n - tetradecane is 30:65:5.

[0082] Example 5

[0083] An anti - freeze water - stable material includes the phase - change recycled aggregate of Example 1, brick - concrete aggregate and the second cement material (P.S.A32.5). The mass ratio of the brick - concrete aggregate, phase - change recycled aggregate and the second cement material is 85:10:5.

[0084] Example 6

[0085] An anti - freeze water - stable material, except using the phase - change recycled aggregate in Example 2, other conditions are the same as Example 5.

[0086] Example 7

[0087] An anti - freeze water - stable material, except using the phase - change recycled aggregate in Example 3, other conditions are the same as Example 5.

[0088] Example 8

[0089] An anti - freeze water - stable material, except using the phase - change recycled aggregate in Example 4, other conditions are the same as Example 5.

[0090] Example 9

[0091] An anti-freezing water-stable material, comprising the phase-change recycled aggregate, brick-concrete aggregate and second cement material (P.S.A32.5) of Example 1, wherein the mass ratio of the brick-concrete aggregate, phase-change recycled aggregate and second cement material is 86:10:4.

[0092] Example 10

[0093] An anti-freezing water-stable material, comprising the phase-change recycled aggregate, brick-concrete aggregate and second cement material (P.S.A32.5) of Example 1, wherein the mass ratio of the brick-concrete aggregate, phase-change recycled aggregate and second cement material is 84:10:6.

[0094] Example 11

[0095] An anti-freezing water-stable material, comprising the phase-change recycled aggregate, brick-concrete aggregate and second cement material (P.S.A32.5) of Example 1, wherein the mass ratio of the brick-concrete aggregate, phase-change recycled aggregate and second cement material is 83:10:7.

[0096] Example 12

[0097] An anti-freezing water-stable material, comprising the phase-change recycled aggregate, brick-concrete aggregate and second cement material (P.S.A32.5) of Example 1, wherein the mass ratio of the brick-concrete aggregate, phase-change recycled aggregate and second cement material is 75:20:5.

[0098] Comparative Example 1

[0099] A composite material, comprising brick-concrete aggregate and P.S.A32.5 cement, wherein the mass ratio of the brick-concrete aggregate and P.S.A32.5 cement is 95:5.

[0100] Comparative Example 2

[0101] A composite material, comprising brick-concrete aggregate, P.S.A32.5 cement and industrial salt, wherein the mass ratio of the brick-concrete aggregate and P.S.A32.5 cement is 95:5, and the mass content of the industrial salt is 0.1% (the operation method is to add 5% water externally, and the salt concentration is 2%).

[0102] Comparative Example 3

[0103] A composite material, comprising brick-concrete aggregate, P.S.A32.5 cement and concrete powder antifreeze, wherein the mass ratio of the brick-concrete aggregate and P.S.A32.5 cement is 95:5, and the mass content of the concrete powder antifreeze is 0.1%.

[0104] Experimental Example

[0105] 1. Performance test of the phase-change recycled aggregate

[0106] The water absorption of the phase change recycled aggregates in Examples 1-4 was tested according to the test method of JTG 3432, and they were incorporated into 10-20 mm brick-concrete coarse aggregates at a mass ratio of 10%, and the strength test was carried out according to the test method of JTG 3432. The results are shown in Table 1.

[0107] Table 1 Water Absorption of Phase Change Recycled Aggregates

[0108]

[0109] 2. Performance Test of Frost-Resistant Water-Stable Materials

[0110] The frost-resistant water-stable materials in Examples 5-12 and the composite materials in Comparative Examples 1-3 were respectively subjected to performance determination, including:

[0111] (1) 7-day unconfined compressive strength; determination of 28-day freeze-thaw residual compressive strength ratio.

[0112] (2) Outdoor airtight curing was carried out during the winter construction period, and the outdoor temperature was -5°C to 5°C. The 7-day unconfined compressive strength was measured, and the strength loss rate was calculated.

[0113] Table 2 Performance Test of Frost-Resistant Water-Stable Materials

[0114]

[0115] The frost-resistant water-stable materials obtained by the method of the present invention have appropriate strength at normal temperature and can meet the grade of 3.5 MPa; under the condition of lower outdoor temperature, the 7-day unconfined compressive strength is high, the strength loss rate is small, the frost resistance performance is excellent, and the test blocks are relatively complete as a whole. Using the phase change recycled aggregates can effectively guarantee the hydration conditions of cement and promote the growth of water-stable strength under winter conditions.

[0116] For the composite material of Comparative Example 1, no phase change recycled aggregate was added, the 28-day freeze-thaw residual compressive strength ratio decreased, the frost resistance performance was poor, the strength loss was very high, and the surface was obviously frozen and crumbled.

[0117] For the composite material of Comparative Example 2, industrial salt needs to be dissolved in water for addition. There are relatively large problems in the current production situation, addition method and concentration control. The 28-day freeze-thaw residual compressive strength ratio decreases, the frost resistance performance is poor, the strength loss is relatively high, and the surface is obviously frozen and crumbled.

[0118] For the composite material of Comparative Example 3, the powder was seriously adhered to the surface of the rough recycled aggregates during dry mixing and it was difficult to stir evenly, which may also be the reason for its poor effect; the 28-day freeze-thaw residual compressive strength ratio decreased, the frost resistance performance was poor, the strength loss was relatively high, and the surface was obviously frozen and crumbled.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A phase-change recycled aggregate, characterized in that: It comprises a base material and a packaging layer coated on the surface of the base material, wherein the base material comprises a porous decoration waste aggregate structure and an organic phase change material, and the organic phase change material is located in the gaps of the porous decoration waste aggregate structure; The porous renovation waste aggregate structure includes aerated concrete aggregate; The encapsulation layer includes a first cementitious material.

2. The phase change recycled aggregate according to claim 1, characterized in that: Contains at least one of the following features (1) to (2): (1) The thickness of the encapsulation layer is 0.5 to 2.0 mm; (2) The particle size of the aerated concrete aggregate is 5 to 25 mm.

3. The phase change recycled aggregate according to claim 1, characterized in that: The phase change temperature of the organic phase change material is -10 to 10°C; Preferably, the organic phase change material comprises a paraffin phase change material; Preferably, the paraffin-based phase change material includes tetradecane.

4. The phase change recycled aggregate according to claim 1, characterized in that: The water absorption rate of the porous decoration waste aggregate structure is 15% to 25%; The water absorption rate of the phase-change recycled aggregate is less than 10%.

5. The phase change recycled aggregate according to claim 1, characterized in that: The first cement material includes ordinary Portland cement, early strength cement or quick-setting cement having a 28d compressive strength greater than or equal to 42.5 MPa.

6. The method for preparing phase-change recycled aggregate according to any one of claims 1 to 5, characterized in that: The following steps are involved: The aerated concrete aggregate is infiltrated with a liquid organic phase change material, and then cooled and solidified to obtain a matrix material; The base material is wrapped with a slurry of the first cement material, and phase-change recycled aggregate is obtained after curing.

7. The method for preparing phase-change recycled aggregate according to claim 6, characterized in that: Contains at least one of the following features (1) to (4): (1) The mass ratio of the porous renovation waste aggregate, the organic phase change material and the first cement material is (30-70):(5-10):(20-70); (2) The duration of the immersion treatment is less than or equal to 5 minutes; (3) Vibration operation or vacuum operation is used during the infiltration process; (4) The slurry is cement slurry, the amount of water added is 30% to 70%, and the amount of water reducing agent is 0.2% to 1%.

8. An antifreeze water-stable material, characterized in that: It comprises the phase-changing recycled aggregate, brick-concrete aggregate and second cement material according to any one of claims 1 to 5; The mass content of the phase-change recycled aggregate in the antifreeze water-stabilizing material is 10% to 20%.

9. The antifreeze water-stable material according to claim 8, characterized in that: Contains at least one of the following features (1) to (3): (1) The mass content of the brick-concrete aggregate in the antifreeze water-stabilizing material is 70% to 85%; the mass content of the second cement material in the antifreeze water-stabilizing material is 4% to 7%; (2) the second cement material comprises slag silicate cement or other slow-setting cement for roads having a 28d compressive strength greater than or equal to 32.5 MPa; (3) The method for preparing the antifreeze water-stable material comprises: mixing phase-change recycled aggregate, brick-concrete aggregate, an appropriate amount of water and a second cement material.

10. The antifreeze water-stable material according to claim 8, characterized in that: Contains at least one of the following features (1) to (3): (1) The 7d unconfined compressive strength of the antifreeze water-stabilizing material is 2.0 to 4.0 MPa; (2) The 28d freeze-thaw residual compressive strength ratio of the antifreeze water-stable material is 95% to 97%; (3) The antifreeze water-stabilizing material has a 7-day unconfined compressive strength loss of 5% to 10% when cured at an outdoor temperature of -5 to 5°C in winter.

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