Phase-change self-repairing lightweight aggregate concrete material and preparation method thereof

Abstract

The invention provides a phase-change self-repairing lightweight aggregate concrete material and a preparation method thereof.The method comprises the steps that 1, phase-change self-repairing lightweight aggregates prepared from hexadecane, dodecanol, decanoic acid, lauric acid, tetradecanoic acid and a repairing agent are mixed according to the mass ratio of 1: 1: 1: 1: 1, and composite phase-change self-repairing lightweight aggregates are obtained; secondly, the shale pottery sand is pre-wetted to reach a saturated surface dry state; 3, uniformly dry-mixing silica fume, cement, fly ash, floating beads and nano-silica in a concrete mixer to obtain a primarily mixed dry material; 4, adding composite phase change self-repairing lightweight aggregate, 50% of water, 50% of an additive and 50% of carbon fibers into the primarily mixed dry material, and uniformly stirring to obtain a medium mixed material; and 5, adding shale pottery sand, 50% of water, 50% of an additive and 50% of carbon fibers into the medium mixture, and uniformly stirring to obtain the phase-change self-repairing lightweight aggregate concrete.

Description

Technical Field

[0001] This invention belongs to the field of concrete technology, and specifically relates to a phase change self-healing lightweight aggregate concrete material and its preparation method. Background Technology

[0002] Traditional thermal storage materials, such as cement-based thermal storage materials, while achieving thermal storage functions to some extent, still have room for improvement in terms of thermal storage density and heat release efficiency. Furthermore, the preparation of traditional thermal storage materials often relies on large amounts of energy-intensive raw materials, increasing costs and potentially impacting the environment. In recent years, phase change materials (PCMs) have shown great potential in the thermal storage field due to their high thermal storage density and heat release efficiency. However, directly applying PCMs to building materials presents challenges such as easy leakage and poor compatibility with existing building materials. Currently, methods such as directly incorporating PCMs into concrete or encapsulating them in concrete through simple physical wrapping improve the thermal storage performance of concrete to some extent, but suffer from low PCM loading rate, poor encapsulation effect, and low heat release efficiency. Moreover, these methods fail to consider the impact of microcracks caused by temperature changes and loads during concrete use on thermal storage performance and durability, lacking an effective self-healing mechanism.

[0003] Therefore, how to provide a phase change self-healing lightweight aggregate concrete material and its preparation method is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the problems of easy leakage and poor compatibility with building materials in existing phase change materials, this invention proposes a phase change self-healing lightweight aggregate concrete material and its preparation method. The lightweight phase change self-healing aggregate incorporates a self-healing functional component. When micro-cracks appear in the concrete due to temperature changes or external forces, this component is released as the cracks expand, achieving self-repair through chemical reaction or physical filling, effectively improving the material's durability and service life. By introducing this type of lightweight phase change self-healing aggregate and combining it with a specific preparation process, this invention aims to provide a phase change self-healing lightweight concrete material with high heat storage performance, good compatibility and stability, and self-healing capabilities, to meet the needs of temperature control and self-healing in large-volume concrete and promote the sustainable development of the building materials industry.

[0005] The technical solution of the present invention regarding a phase change self-healing lightweight aggregate concrete material and its preparation method is as follows:

[0006] A method for preparing a phase change self-healing lightweight aggregate concrete material includes the following steps:

[0007] Step S1: The phase change self-healing lightweight aggregates prepared by hexadecane, dodecanol, decanoic acid, lauric acid, tetradecanoic acid and repair agent are mixed in a mass ratio of 1:1:1:1:1 to obtain composite phase change self-healing lightweight aggregates.

[0008] Step S2: Pre-wet the shale ceramic sand until it reaches a saturated surface-dry state;

[0009] Step S3: Dry mix silica fume, cement, fly ash, cenospheres, and nano silica in a concrete mixer to obtain a preliminary dry mix.

[0010] Step S4: Add composite phase change self-healing lightweight aggregate, 50% water, 50% additives, and 50% carbon fiber to the initial dry mixture, and stir evenly to obtain the intermediate mixture.

[0011] Step S5: Add shale ceramsite sand, 50% water, 50% admixture, and 50% carbon fiber to the medium-mixed materials, and stir evenly to obtain phase change self-healing lightweight aggregate concrete.

[0012] Further, in step S1, the method for preparing phase change self-healing lightweight aggregate includes:

[0013] The first step is to place the lightweight aggregate in an oven at 105±5℃ and dry it until it reaches a constant weight;

[0014] The second step is to put the phase change material into a beaker, and then put the beaker containing the phase change material into an oven for heating to ensure that the phase change material is in a liquid state. The phase change material includes: hexadecane, dodecanol, decanoic acid, lauric acid and tetradecanoic acid.

[0015] The third step is to place the vacuum barrel in a constant temperature water bath. After the temperature inside the vacuum barrel reaches 60°C, place the phase change material, repair agent and lightweight aggregate inside the vacuum barrel.

[0016] The fourth step is to set the vacuum adsorption pressure to 0.1 MPa and the adsorption time to 90 min, so that the phase change material and the repair agent are fully adsorbed into the internal pores of the lightweight aggregate.

[0017] After the fifth step of adsorption is completed, remove the lightweight aggregate, wipe off the residual phase change material and repair agent on the surface, place it in cold water to condense, wait for it to cool and solidify, and then let it dry.

[0018] The sixth step is to mix the epoxy resin and the curing agent in a 1:1 ratio and place them in an oven to preheat to 30°C for later use.

[0019] Step 7: Add the phase change aggregate to the epoxy resin solution and stir to coat the surface of the phase change self-healing lightweight aggregate with epoxy resin; after initial curing, remove it for later use.

[0020] The eighth step is to mix the geopolymer slurry, add graphite powder and 0.03% chopped carbon fiber to the slurry and mix well. Add the epoxy resin-coated phase change self-healing lightweight aggregate to the geopolymer slurry so that the geopolymer slurry coats the surface of the aggregate. Once the slurry coats the surface of the aggregate, remove it immediately, let it cure and set it aside for later use.

[0021] The ninth step involves uniformly spraying a 5% polyacrylate solution onto the surface of the phase change self-healing lightweight aggregate, followed by curing in an 80°C oven for 1 hour to form a uniform polymer film, thus producing the phase change self-healing lightweight aggregate.

[0022] Furthermore, the hexadecane has a phase transition temperature of 18.2℃, a latent heat of phase transition of 200 J / g, and a density of 0.834 g / cm³. 3 Its boiling point is 286.8℃; the phase transition temperature of dodecanol is 25.8℃, the latent heat of phase transition is 216 J / g, and its density is 0.831 g / cm³. 3 Its boiling point is 258.0℃; the phase transition temperature of decanoic acid is 31.4℃, the latent heat of phase transition is 167 J / g, and its density is 0.893 g / cm³. 3 Its boiling point is 269.6℃; the phase transition temperature of lauric acid is 43.4℃, the latent heat of phase transition is 212 J / g, and its density is 0.867 g / cm³. 3 Its boiling point is 299.0℃; its phase transition temperature is 53.7℃, its latent heat of phase transition is 187 J / g, and its density is 0.862 g / cm³. 3 Its boiling point is 250.5℃.

[0023] Furthermore, the lightweight aggregate includes: fly ash ceramsite, shale ceramsite, clay ceramsite, coal gangue ceramsite, pumice, and expanded perlite.

[0024] Furthermore, the repair agent includes: sodium carbonate solution, sodium silicate solution, a mixture of sodium silicate and sodium nitrate, and sodium monofluorophosphate solution.

[0025] This invention also provides a phase change self-healing lightweight aggregate concrete material, prepared using the same preparation method, wherein the components of the phase change self-healing lightweight aggregate concrete material are specified in kg / m³. 3 The mass ratio is as follows: self-healing phase change lightweight aggregate 730-870; shale ceramic sand 240-380; cement 450-50; silica fume 40-60; fly ash 0-30; water-reducing agent 5-7; cenospheres 0-61.4; nano silica 0-15; water 50-80; carbon fiber 1.5-7.5.

[0026] Compared with the prior art, the phase change self-healing lightweight aggregate concrete material of the present invention has the following technical effects:

[0027] 1. High phase change material loading rate: By utilizing the porous structure and high specific surface area of ​​lightweight porous materials, phase change materials are effectively loaded into lightweight aggregates, thereby improving the utilization rate of phase change materials and the heat storage capacity of concrete.

[0028] 2. Excellent energy storage performance: The introduction of enhanced energy storage materials further improves the energy storage performance of concrete, enabling it to absorb and release heat more effectively.

[0029] 3. Good stability and durability: Through encapsulation treatment, phase change aggregates are effectively protected, improving their stability and durability and extending the service life of concrete.

[0030] 4. Excellent self-healing ability: The self-healing functional components pre-set in the lightweight aggregate can trigger a repair reaction when micro-cracks occur in the concrete. The cracks are closed by physical filling or chemical bonding, avoiding the damage to heat storage performance caused by crack expansion and further extending the service life of the material.

[0031] 5. Environmental protection and sustainability: All raw materials meet environmental standards, promoting resource recycling and sustainable development. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a method for preparing a phase change self-healing lightweight aggregate concrete material according to an embodiment of the present invention. Detailed Implementation

[0033] The phase change self-healing lightweight aggregate concrete material and its preparation method of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0034] refer to Figure 1 This invention provides a detailed description of the phase change self-healing lightweight aggregate concrete material and its preparation method.

[0035] Example 1:

[0036] A method for preparing a phase change self-healing lightweight aggregate concrete material includes the following steps:

[0037] Step S1: The phase change self-healing lightweight aggregates prepared by hexadecane, dodecanol, decanoic acid, lauric acid and tetradecanoic acid respectively are mixed in a mass ratio of 1:1:1:1:1 to obtain composite phase change self-healing lightweight aggregates.

[0038] Step S2: Pre-wet the shale clay sand until it reaches a saturated, surface-dry state;

[0039] S3: Dry mix silica fume, cement, fly ash, cenospheres, and nano silica in a concrete mixer for 1.0 min until uniformly mixed to obtain the initial dry mix.

[0040] S4: Add phase change self-healing lightweight aggregate, 50% water, 50% additives, and 50% carbon fiber to the initial dry mixture, stir for 1 minute to form a medium mixture.

[0041] S5: Add shale ceramsite sand, 50% water, 50% admixture, and 50% carbon fiber to the medium-mixed materials, and stir for 1 minute to obtain phase change self-healing lightweight aggregate concrete. This embodiment also provides a phase change self-healing lightweight aggregate concrete material, prepared using a method for preparing phase change self-healing lightweight aggregate concrete materials, including phase change self-healing lightweight aggregate; shale ceramsite sand; cement; silica fume; fly ash; water-reducing agent; cenospheres; nano-silica; water; and carbon fiber.

[0042] Examples 2 to 5:

[0043] The difference between Examples 2 to 4 and Example 1 lies in the different mass ratios of the phase change self-healing lightweight aggregates prepared using hexadecane, dodecanol, decanoic acid, lauric acid, and tetradecanoic acid. The mass ratios for Examples 2 to 4 are 1:2:2:2:3, 1:1:2:3:3, and 1:1:2:2:4, respectively. Example 5 incorporates ordinary lightweight aggregates with the same dosage as the phase change self-healing lightweight aggregates. Detailed values ​​are shown in Table 1. Table 1 shows the weight parts of each component in the phase change lightweight aggregate concrete.

[0044] Table 1. Weight parts of each component in phase change self-healing lightweight aggregate concrete

[0045]

[0046] Performance testing:

[0047] The concrete specimens prepared in each embodiment were subjected to compressive strength and splitting tensile strength tests. The concrete specimens were 100mm×100mm×100mm cubes, with 6 specimens per group. For thermodynamic performance testing, 3 concrete slabs were used, with specimen dimensions of 300mm×300mm×35mm. Crack self-healing performance tests were conducted according to T / CECS 913-2021 "Standard for Test Methods of Self-Healing Performance of Cement Concrete". The specimen dimensions were Ф100mm×50mm, with one group each of reference concrete and tested concrete specimens, and 8 specimens per group. After molding, the specimens were cured according to standard methods (temperature 20℃±2℃, relative humidity above 95%RH). The performance test results are shown in Table 2.

[0048] Table 2. Test results of phase change lightweight aggregate concrete material properties

[0049]

[0050] The test data from Examples 1 to 5 show that the compressive strength and splitting tensile strength of the phase change self-healing lightweight aggregate concrete are significantly improved compared to concrete using ordinary lightweight aggregate. The 28-day compressive strength of Example 1 reached 42.3 MPa, an increase of 16.8% compared to Example 5, and the splitting tensile strength increased by 33.3%. Comparing Examples 2 to 4, the mechanical properties fluctuated with changes in the mass ratio of hexadecane, dodecanol, decanoic acid, lauric acid, and tetradecanoic acid phase change materials, but all were higher than those of Example 5. Specific heat capacity and thermal conductivity showed an increasing trend, but Example 1 had the lowest temperature peak (28.1℃), indicating that the phase change self-healing lightweight aggregate prepared using hexadecane, dodecanol, decanoic acid, lauric acid, and tetradecanoic acid, mixed in a mass ratio of 1:1:1:1:1, forms an optimal thermal regulation network in the concrete, resulting in the best thermal regulation performance of Example 1. The data on the recovery rate of seepage pressure further confirmed that Example 1 had the best self-healing performance (96.4%), which was much higher than Example 5 (57.9%), indicating that the synergistic effect of phase change material and repair agent significantly improved the self-healing ability of concrete.

[0051] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for preparing a phase change self-healing lightweight aggregate concrete material, characterized by, It comprises the following steps: Step S1, the phase change self-repairing lightweight aggregate prepared by mixing hexadecane, dodecanol, capric acid, lauric acid, and myristic acid with the repairing agent in a mass ratio of 1:1:1:1:1 is obtained; Step S2, shale pottery sand is pre-wetted to reach a saturated surface dry state; Step S3, silica fume, cement, fly ash, floating beads, and nano-silicon dioxide are uniformly dry-mixed in a concrete mixer to obtain initial mixed dry materials; Step S4, the initial mixed dry materials are added with the composite phase change self-repairing lightweight aggregate, 50% water, 50% admixture, and 50% carbon fiber, and uniformly stirred to obtain intermediate mixed materials; Step S5, shale pottery sand, 50% water, 50% admixture, and 50% carbon fiber are added to the intermediate mixed materials, and uniformly stirred to obtain the phase change self-repairing lightweight aggregate concrete.

2. The production method according to claim 1, characterized by, In the step S1, the phase change self-repairing lightweight aggregate preparation method comprises: Firstly, the lightweight aggregate is placed in a 105±5℃ oven and baked until the weight is constant; Secondly, the phase change material is placed in a beaker, and the beaker containing the phase change material is placed in an oven for heating to ensure that the phase change material is in a liquid state, wherein the phase change material comprises hexadecane, dodecanol, capric acid, lauric acid, and myristic acid; Thirdly, the vacuum barrel is placed in a constant temperature water bath, and after the temperature in the vacuum barrel reaches 60℃, the phase change material, the repairing agent, and the lightweight aggregate are placed in the vacuum barrel; Fourthly, the vacuum adsorption pressure is set to 0.1MPa, and the adsorption time is 90min, so that the phase change material and the repairing agent are fully adsorbed into the internal pores of the lightweight aggregate; Fifthly, after the adsorption is completed, the lightweight aggregate is taken out, the residual phase change material and repairing agent on the surface are wiped off, and the lightweight aggregate is placed in cold water for condensation, cooled, and dried; Sixthly, the epoxy resin and the curing agent are mixed in a ratio of 1:1 and placed in an oven for preheating to 30℃; Seventhly, the phase change aggregate is added to the epoxy resin solution and stirred to coat the surface of the phase change self-repairing lightweight aggregate with the epoxy resin, and after preliminary solidification, the phase change self-repairing lightweight aggregate is taken out for standby; Eighthly, the geopolymer slurry is prepared, and graphite powder and 0.03% chopped carbon fiber are added to the slurry and uniformly stirred, and the phase change self-repairing lightweight aggregate coated with the epoxy resin is added to the geopolymer slurry to wrap the surface of the lightweight aggregate, and after the slurry wraps the surface of the lightweight aggregate, the geopolymer slurry is immediately taken out and solidified for standby; Ninthly, a 5% polyacrylate solution is uniformly sprayed on the surface of the phase change self-repairing lightweight aggregate, and then solidified in an 80℃ oven for 1 hour to form a uniform polymer film, thereby obtaining the phase change self-repairing lightweight aggregate.

3. The preparation method according to claim 2, characterized in that, The hexadecane phase transition temperature is 18.2°C, the phase transition latent heat is 200 J / g, and the density is 0.834 g / cm 3 , the boiling point is 286.8°C; the dodecanol phase transition temperature is 25.8°C, the phase transition latent heat is 216 J / g, and the density is 0.831 g / cm 3 , the boiling point is 258.0°C; the decanoic acid phase transition temperature is 31.4°C, the phase transition latent heat is 167 J / g, and the density is 0.893 g / cm 3 , the boiling point is 269.6°C; the lauric acid phase transition temperature is 43.4°C, the phase transition latent heat is 212 J / g, and the density is 0.867 g / cm 3 , the boiling point is 299.0°C; the myristic acid phase transition temperature is 53.7°C, the phase transition latent heat is 187 J / g, and the density is 0.862 g / cm 3 , the boiling point is 250.5°C.

4. The production method according to claim 2, characterized by, The lightweight aggregate comprises fly ash pottery, shale pottery, clay pottery, coal gangue pottery, pumice, and expanded perlite.

5. The preparation method according to claim 2, characterized in that, The repairing agent comprises sodium carbonate solution, sodium silicate solution, sodium silicate and sodium nitrate mixed solution, and sodium monofluorophosphate solution.

6. A phase change self-healing lightweight aggregate concrete material, characterized by, The phase change self-healing lightweight aggregate concrete material is prepared by the preparation method of any one of claims 1 to 5, wherein each component of the phase change self-healing lightweight aggregate concrete material is prepared according to kg / m³. 3 The mass ratio is: 730-870 for self-healing phase change lightweight aggregate; Shale pottery sand 240-380; cement 450-50; silica fume 40-60; fly ash 0-30; water reducing agent 5-7; Floating beads 0-61.4; nano-silicon dioxide 0-15; water 50-80; carbon fiber 1.5-7.5.

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