Porous baking-free lightweight aggregate with sound absorption and heat preservation functions and preparation method of porous baking-free lightweight aggregate

Abstract

The invention relates to a porous unfired lightweight aggregate with sound absorption and heat preservation functions and a preparation method thereof. The method comprises the following steps: preparing an activating agent, treating a solid waste raw material, mixing the solid waste raw material with the activating agent, activating, forming pores, curing, accelerating carbonation treatment and the like. The steps are specifically set, so that the finally obtained porous unfired lightweight aggregate has relatively high strength and also keeps low thermal conductivity and good sound absorption performance, and resource utilization of industrial solid wastes is realized by adopting solid waste raw materials.

Description

Technical Field

[0001] The invention belongs to the technical field of building material preparation, and particularly relates to a porous, unburned lightweight aggregate with sound absorption and heat insulation functions and a preparation method thereof. Background Art

[0002] Lightweight aggregate concrete has attracted widespread attention due to its low structural deadweight, making it suitable for thermal insulation, sound insulation and earthquake-resistant buildings. The apparent density is less than 1950kg / m 3 Lightweight aggregate concrete is made by using lightweight aggregate (bulk density ≤ 1200kg / m 3 ), binders and additives. Among them, lightweight aggregate accounts for 65%-75% of the volume of concrete. Commonly used lightweight aggregates are sintered types, usually sintered at high temperatures (>1000℃). The application of unfired lightweight aggregate in lightweight aggregate concrete has attracted much attention due to its low energy consumption and environmental friendliness. Functionalized unfired lightweight aggregate with good sound absorption and thermal insulation properties makes it more valuable for application in modern buildings. The sound absorption and thermal insulation properties of unfired lightweight aggregate are mainly determined by porosity. However, porosity is generally negatively correlated with mechanical strength. Therefore, improving the mechanical strength of unfired lightweight aggregate while maintaining high porosity is crucial for its practical application.

[0003] Chinese invention patent publication CN118561560A discloses a porous metal lightweight ultra-high performance concrete composite material and its preparation method. By improving the compressive strength of the composite material composed of lightweight ultra-high performance concrete and porous metal to a certain extent and increasing the ultimate strain by more than 1 times, the energy absorption efficiency will be improved when used in anti-collision structures; however, this technical solution does not take into account the sound absorption and thermal insulation properties.

[0004] Accelerated carbonation has attracted widespread attention in the building materials industry due to its ability to permanently fix carbon and enhance the mechanical properties of cementitious materials. The strengthening mechanism of cementitious materials by accelerated carbonation is attributed to the reaction of CO2 with calcium-magnesium phase to generate CaCO3 and silica gel, which fills the pores of the matrix. In the journal Resources, Conservation and Recycling, "Use of CO2-active BOFS binder in the production of artificial aggregates with waste concrete powder" was disclosed, which showed that the mechanical strength of air-cured steel slag-based unburned aggregate increased by 30-109% under accelerated carbonation. Although the effect of accelerated carbonation on dense unburned aggregate (higher bulk density) has been extensively studied, the effect of accelerated carbonation on porous unburned lightweight aggregate remains unknown, especially the changes in pore structure and the strengthening mechanism.

[0005] Because the mechanical strength and porosity of unfired lightweight aggregate are negatively correlated, an increase in porosity is accompanied by a decrease in mechanical strength, limiting its functional applications in the construction industry. Furthermore, prior art research on unfired lightweight aggregate with sound absorption and thermal insulation properties is limited. Therefore, it is necessary to develop a porous unfired lightweight aggregate with sound absorption and thermal insulation properties, as well as a preparation method that can efficiently utilize industrial solid waste, to address the shortcomings of prior art and solve one or more of the aforementioned problems. Summary of the Invention

[0006] In response to the above technical problems, the present invention proposes a porous unfired light aggregate with sound absorption and heat preservation functions and a preparation method. Using typical silico-aluminous solid waste and high-calcium solid waste (preferably fly ash and blast furnace slag as examples) as raw materials, the porous unfired light aggregate is prepared using foaming technology. By accelerating carbonation, the mechanical strength is improved, the sound absorption frequency band range of the porous unfired light aggregate is changed, and good heat preservation performance is maintained at the same time. The porous unfired light aggregate prepared by the method of the present invention not only absorbs industrial solid waste, but also fixes greenhouse gas CO2, realizing waste resource utilization. In addition, the high porosity gives the unfired light aggregate functional properties - sound absorption and heat preservation, which broadens the application range of the unfired light aggregate.

[0007] This is achieved through the following technical means:

[0008] A method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions comprises the following steps:

[0009] S1. Add water to the alkaline salt and / or base, stir thoroughly and dissolve in water to obtain an activator.

[0010] S2. Dry the typical silicoaluminous solid waste and high-calcium solid waste to constant weight, and then sieve to obtain small-particle typical silicoaluminous solid waste and high-calcium solid waste, and then mix the typical silicoaluminous solid waste and high-calcium solid waste in a weight ratio of (10-4): (0-6) to obtain a solid waste raw material.

[0011] S3. Add the activator obtained in S1, which accounts for 30 to 60 wt.% of the solid waste raw materials, to the solid waste raw materials obtained in S2, and stir thoroughly to obtain an alkali-activated slurry.

[0012] S4. Add 0.5-4.0 wt. % (preferably 0.6-3.0 wt. %) of a pore-forming agent to the alkali-activated slurry obtained in S3 and stir to obtain a pre-foamed slurry.

[0013] S5. Inject the pre-foamed slurry obtained in S4 into the mold, and then place the mold in a curing box for curing and solidification.

[0014] S6. Demolding the material obtained after curing in S5, and then placing the demolded particles in a carbonization box for carbonization treatment to obtain porous unburned lightweight aggregate.

[0015] According to the above aspects and any possible implementation, an implementation is further provided, wherein the alkaline salt and / or base is industrial grade sodium silicate and sodium hydroxide mixed in a weight ratio of (29 to 33): (3 to 7).

[0016] According to the above aspects and any possible implementation, an implementation is further provided, wherein the modulus of the activator in step S1 is 1.2 to 1.6 (more preferably 1.4).

[0017] According to the aspects and any possible implementations described above, an implementation is further provided, in which in step S1, the alkaline salt and / or base is added to water, fully stirred and dissolved in water, specifically adding the alkaline salt and / or base to deionized water at 80-100°C, specifically adding the alkaline salt and / or base to deionized water at 80-100°C, and then fully stirring at this temperature until it becomes clear, and the ratio of the alkaline salt and / or base to the deionized water is (1-3):(0.5-2).

[0018] According to the above aspects and any possible implementation, an implementation is further provided, in step S2, the drying temperature of typical industrial solid waste and high-calcium solid waste is 100-110°C, and the drying time is 12-48 hours.

[0019] According to the aspects and any possible implementations described above, an implementation is further provided, wherein the particle size of the typical siliceous and aluminous solid waste and high-calcium solid waste is less than 0.075 mm.

[0020] According to the above aspects and any possible implementations, further provided is an implementation, wherein the typical silicoaluminous solid waste is fly ash and / or coal gangue; and the high-calcium solid waste is blast furnace slag, steel slag (herein, steel slag is slag produced during the steelmaking process, such as converter slag or electric furnace slag), and / or sintering red mud. Further preferred combinations of the two include fly ash and blast furnace slag, fly ash and sintering red mud, coal gangue and sintering red mud, or coal gangue and steel slag.

[0021] As an alternative, the typical silicon-alumina solid waste and high-calcium solid waste in step S2 are replaced by a single high-calcium solid waste, wherein the high-calcium solid waste is blast furnace slag, steel slag and / or sintering red mud.

[0022] According to the above aspects and any possible implementation, an implementation is further provided, in step S3, the stirring speed for sufficient stirring is 200 to 500 rpm / min, and the stirring time is 2 to 5 minutes.

[0023] According to the above aspects and any possible implementation, an implementation is further provided, in step S4, the pore-forming agent is hydrogen peroxide (H2O2) with a volume fraction of 30% (further selection, for example, hydrogen peroxide with a volume fraction of 25-35%), the stirring speed is 200-400 rpm / min, and the stirring time is 1-3 minutes.

[0024] According to the aspects and any possible implementation methods described above, an implementation method is further provided. In step S5, the mold is a spherical mold, and the spherical mold is a 27-connected mold with a diameter of 10 to 13 mm (the 27-connected mold is a known mold, specifically a spherical plate mold with three rows and nine pieces in each row); the curing temperature of the curing box is 60 to 80°C, and the curing time is 10 to 13 hours (preferably 12 hours).

[0025] According to the aspects and any possible implementation methods described above, an implementation method is further provided. In step S6, the particles obtained after demolding are spherical particles, the CO2 concentration during carbonization treatment is 20-40%, the humidity is 70-100% RH, and the temperature in the carbonization box is 25-40°C.

[0026] The carbonization treatment preferably comprises the following steps:

[0027] I. Place the obtained spherical particles in a tray and set the temperature in the carbonization box to 25-40° C. and the humidity to 70-100% RH.

[0028] II. Place the tray in a carbonization box and introduce CO2 gas into the carbonization box. When the CO2 concentration in the carbonization box reaches 20-40%, stop the ventilation and maintain the carbonization box at normal pressure. The spherical particles are accelerated to carbonate in the carbonization box for 8-16 hours.

[0029] III. After the treatment time is over, the tray containing the spherical particles is taken out to complete the accelerated carbonation treatment.

[0030] A porous unfired lightweight aggregate with sound absorption and heat insulation functions is prepared by the above-mentioned preparation method.

[0031] The porous unburned lightweight aggregate has a cylinder compressive strength of 2.2-3.56 MPa and a bulk density of 580-635 kg / m 3 The water absorption rate is 20-27%, the thermal conductivity is 0.25-0.28W / (m·K), the sound absorption band shifts to the high frequency of 2500-3500Hz, and the peak sound absorption coefficient is 0.5-0.6.

[0032] The technical effects of the present invention are:

[0033] (1) The present invention prepares unburned lightweight aggregate by foaming technology to increase porosity, and optimizes the pore structure and mechanical properties of porous unburned lightweight aggregate by accelerating carbonation. For gel pores and transition pores, Ca 2+ The leaching of Ca leads to the polymerization and contraction of aluminosilicate chains, increasing the proportion of gel pores and transition pores; for macropores, the leached Ca 2+ The reaction with CO2 forms a large amount of CaCO3 on the pore walls, refining the pore diameter, improving pore closure, and reducing the proportion of large pores. By combining foaming technology with accelerated carbonation technology, the pore structure is changed, thereby improving the mechanical strength of the porous unfired lightweight aggregate and shifting the sound absorption band (from medium to high frequencies) while maintaining low thermal conductivity. Through this specific configuration, the present invention imparts functional properties to the unfired lightweight aggregate, expanding its application range.

[0034] (2) The present invention prepares lightweight aggregate by setting typical silicoaluminous solid waste and utilizing the advantages of high activity silicoalumina and low density. More importantly, a specific proportion of high calcium solid waste is set, and its high calcium and other characteristics are utilized to strengthen the occurrence of subsequent carbonation reaction and more conducive to the generation of calcium carbonate. By mixing typical silicoaluminous solid waste (such as fly ash) and high calcium solid waste (such as blast furnace slag) in specific proportions to adapt to the specific foaming and accelerated carbonation treatment of the present invention, and by coordinating the specific parameters of each step, the technical solution of the present invention can obtain a porous fire-free lightweight aggregate product that meets the performance of thermal insulation and sound absorption functions. More importantly, the technical solution of the present invention in this specific setting method not only absorbs industrial solid waste, but also fixes the greenhouse gas CO2, realizes the resource utilization of industrial solid waste, and thus realizes the overall transformation of harm into benefit. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic flow chart of the method for preparing porous unburned lightweight aggregate of the present invention.

[0036] Figure 2 This is a comparison chart of the single particle strength and pore structure of porous unburned lightweight aggregate that has not undergone accelerated carbonation.

[0037] Figure 3 Graph showing the cylinder pressure strength comparison data of each embodiment and comparative example.

[0038] Figure 4 It is a data diagram of bulk density comparison between each embodiment and comparative example.

[0039] Figure 5 It is a comparative data diagram of water absorption rate of each embodiment and comparative example.

[0040] Figure 6 1 is a comparative data chart of thermal conductivity and sound absorption coefficient between Example 1 and Comparative Example 1.

[0041] Figure 7 The pore structure characterization and porosity comparison data of Example 1 and Comparative Example 1 are shown. DETAILED DESCRIPTION

[0042] The process technology scheme of the present invention is further illustrated below by combining embodiments and drawings. The orientations involved in this specification are based on the orientations of the present invention during normal operation, and do not limit the orientations during storage and transportation. They only represent relative positional relationships, not absolute positional relationships. Specific implementation methods Unless otherwise specified, each feature is only an example of a series of equivalent or similar features. It is only to help understand the present invention. Those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0043] The specific implementation method is implemented and compared by the following methods:

[0044] A method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions, specifically as follows Figure 1 As shown, the steps included are as follows:

[0045] (1) Industrial grade sodium silicate and sodium hydroxide (the ratio of the two is 31:5) are added to deionized water and stirred at 90°C until clear to obtain an activator with a modulus of 1.4.

[0046] (2) Dry the fly ash and blast furnace slag at 105°C for 20 hours to constant weight, and then sieve to obtain fly ash and blast furnace slag with a particle size of less than 0.075 mm. Then, mix the fly ash and blast furnace slag to obtain solid waste raw materials.

[0047] (3) 25 g of the activator prepared in step (1) was mixed with 50 g of solid waste raw materials (the ratios of fly ash and blast furnace slag were 10:0, 8:2 and 6:4, respectively) at a stirring speed of 300 rpm / min for 3 minutes to obtain an alkali-activated slurry.

[0048] (4) 0.6 wt.%, 1.0 wt.%, 2.0 wt.% and 3.0 wt.% of hydrogen peroxide were added to the alkali-activated slurry in step (3), respectively, and mixed at a stirring speed of 200 rpm / min for 1 minute to obtain a pre-foamed slurry.

[0049] (5) The pre-foamed slurry in step (4) was injected into a spherical mold, and the porous spherical particles were demoulded after curing at 70° C. for 12 hours.

[0050] (6) The obtained porous spherical particles were characterized by single particle strength and pore structure to determine the carbonized sample with the best “strength-porosity”.

[0051] The single particle strength and pore structure test of the product are as follows Figure 2 As shown, Figure 2 The left side shows the effect of adding hydrogen peroxide on the strength of a single particle, and the right side shows the comparison of pore structures. Figure 2 It can be seen that within the scope defined by the present invention, as the amount of hydrogen peroxide added increases, the overall trend of single particle strength decreases, but after exceeding 2.0wt.%, there is basically no significant effect. The effect of hydrogen peroxide on different ratios of fly ash and blast furnace slag is also different, and the higher the blast furnace slag content, the higher the single particle strength. As for the pore structure, the less hydrogen peroxide is added and the higher the blast furnace slag content, the smaller the pore size. This proves that the ratio of fly ash to blast furnace slag set by the present invention is closely coordinated with the ratio of hydrogen peroxide and is optimal for the application scenario of the present invention.

[0052] The following examples and comparative examples are obtained in combination with this embodiment:

[0053] Example 1:

[0054] A porous unburned lightweight aggregate with sound absorption and heat insulation functions and a preparation method thereof, specifically Figure 1 As shown, the steps included are as follows:

[0055] (1) Industrial grade sodium silicate and sodium hydroxide (the ratio of the two is 31:5) are added to deionized water and stirred at 90°C until clear to obtain an activator with a modulus of 1.4.

[0056] (2) Dry the fly ash and blast furnace slag at 105°C for 20 h to constant weight, and then sieve to obtain fly ash and blast furnace slag with a particle size of less than 0.075 mm. Then, mix the fly ash and blast furnace slag in a weight ratio of 8:2 to obtain a solid waste raw material.

[0057] (3) 25 g of the activator prepared in step (1) was mixed with 50 g of solid waste raw materials (40 g of fly ash and 10 g of blast furnace slag) at a stirring speed of 300 rpm / min for 3 minutes to obtain an alkali-activated slurry.

[0058] (4) 2.0 wt.% hydrogen peroxide was added to the alkali-activated slurry in step (3), and the mixture was mixed at a stirring speed of 200 rpm / min for 1 minute to obtain a pre-foamed slurry.

[0059] (5) The pre-foamed slurry in step (4) was injected into a spherical mold, and after curing at 70° C. for 12 hours, the mold was demoulded to obtain porous spherical particles.

[0060] (6) The porous spherical particles in step (5) are subjected to accelerated carbonation, wherein the specific accelerated carbonation parameters are set to carbonize for 12 hours under the conditions of CO2 concentration of 30%, humidity of 90% RH, and temperature of 30°C to obtain porous unburned lightweight aggregate.

[0061] Example 2:

[0062] A porous, unburned lightweight aggregate with sound absorption and heat insulation functions and a preparation method thereof, comprising the following steps:

[0063] (1) Industrial grade sodium silicate and sodium hydroxide were added to deionized water and stirred at 90°C until the solution was clear to obtain an activator.

[0064] (2) Fly ash and blast furnace slag were dried at 108°C for 26 h to constant weight, and then sieved to obtain fly ash and blast furnace slag with a particle size of less than 0.075 mm. The fly ash and blast furnace slag were then mixed in a weight ratio of 6:4 to obtain a solid waste raw material.

[0065] (3) 25 g of the activator prepared in step (1) was mixed with 50 g of solid waste raw materials (30 g of fly ash and 20 g of blast furnace slag) at a stirring speed of 300 rpm / min for 3 minutes to obtain an alkali-activated slurry.

[0066] (4) 1.0 wt.% hydrogen peroxide was added to the alkali-activated slurry in step (3), and the mixture was mixed at a stirring speed of 200 rpm / min for 1 minute to obtain a pre-foamed slurry.

[0067] (5) The pre-foamed slurry in step (4) was injected into a spherical mold, and after curing at 70° C. for 12 hours, the mold was demoulded to obtain porous spherical particles.

[0068] (6) The porous spherical particles in step (5) are carbonized under the conditions of a CO2 concentration of 30%, a humidity of 90% RH, and a temperature of 30°C for 12 hours to obtain a porous unburned lightweight aggregate.

[0069] Comparative Example 1:

[0070] This comparative example is used to illustrate an example of comparing a material that has not undergone accelerated carbonation treatment with a product of the present invention that has undergone accelerated carbonation treatment, and specifically includes the following steps:

[0071] (1) Industrial grade sodium silicate and sodium hydroxide (the ratio of the two is 31:5) are added to deionized water and stirred at 90°C until clear to obtain an activator.

[0072] (2) 25 g of the activator prepared in step (1) was mixed with 50 g of solid waste raw materials (30 g of fly ash and 20 g of blast furnace slag, i.e., a ratio of 6:4) at a stirring speed of 300 rpm / min for 3 minutes to obtain an alkali-activated slurry.

[0073] (3) 2.0 wt.% hydrogen peroxide was added to the alkali-activated slurry in step (2), and the mixture was mixed at a stirring speed of 200 rpm / min for 1 minute to obtain a pre-foamed slurry.

[0074] (4) The pre-foamed slurry in step (3) was injected into a spherical mold, and after curing at 70° C. for 12 hours, the mold was demoulded to obtain porous spherical particles.

[0075] The performance tests of the products and embodiments are as follows Figures 2 to 7 shown.

[0076] Comparative Example 2:

[0077] This comparative example is used to illustrate an example of comparing a material that has not undergone accelerated carbonation treatment with a product of the present invention that has undergone accelerated carbonation treatment, and specifically includes the following steps:

[0078] (1) Industrial grade sodium silicate and sodium hydroxide were added to deionized water and stirred at 90°C until the solution was clear to obtain an activator.

[0079] (2) 25 g of the activator prepared in step (1) was mixed with 50 g of solid waste raw materials (40 g of fly ash and 10 g of blast furnace slag, i.e., 8:2) at a stirring speed of 300 rpm / min for 3 minutes to obtain an alkali-activated slurry.

[0080] (3) 500 mg of hydrogen peroxide (i.e., 1.0 wt.%) was added to the alkali-activated slurry in step (2), and the mixture was mixed at a stirring speed of 200 rpm / min for 1 minute to obtain a pre-foamed slurry.

[0081] (4) The pre-foamed slurry in step (3) was injected into a spherical mold, and after curing at 70° C. for 12 hours, the mold was demoulded to obtain porous spherical particles.

[0082] The performance tests of the products and embodiments are as follows Figures 2 to 5 shown.

[0083] Comparative Example 3:

[0084] This comparative example is used to illustrate a comparison between a material that has not undergone accelerated carbonation treatment and a product of the present invention that has undergone accelerated carbonation treatment, wherein the solid waste raw material does not contain blast furnace slag but is entirely fly ash, and specifically comprises the following steps:

[0085] (1) Industrial grade sodium silicate and sodium hydroxide were added to deionized water and stirred at 90°C until the solution was clear to obtain an activator.

[0086] (2) 25 g of the activator prepared in step (1) was mixed with 50 g of fly ash at a stirring speed of 300 rpm / min for 3 minutes to obtain an alkali-activated slurry.

[0087] (3) 300 mg of hydrogen peroxide was added to the alkali-activated slurry in step (2), and the mixture was mixed at a stirring speed of 200 rpm / min for 1 minute to obtain a pre-foamed slurry.

[0088] (4) The pre-foamed slurry in step (3) was injected into a spherical mold, and after curing at 70° C. for 12 hours, the mold was demoulded to obtain porous spherical particles.

[0089] The performance tests of the products and embodiments are as follows Figures 2 to 5 shown.

[0090] Performance Testing:

[0091] (1) Single particle strength: The single particle strength of porous spherical particles with different raw material ratios and different H2O2 addition amounts was tested at a loading speed of 10N / s using a microcomputer touch screen pressure testing machine. The test results are as follows: Figure 2 shown.

[0092] (2) Pore structure: The porous spherical particles with different raw material ratios and different H2O2 addition amounts were magnified 30× using an optical microscope to characterize the pore structure. The test results are as follows Figure 2 shown.

[0093] (3) Cylinder pressure strength: Example 1 and Comparative Examples 1-3 were placed in a pressure cylinder using an automatic press to test the cylinder pressure strength. The specific test method is in accordance with the national standard GB / T 17431.2-2010. The test results are as follows: Figure 3 shown.

[0094] (4) Bulk density: The test method for bulk density is as per the national standard GB / T 17431.2-2010. The materials obtained in Example 1 and Comparative Examples 1-3 were tested. The test results are shown in Table 1. Figure 4 shown.

[0095] (5) Water absorption rate: Example 1-3 and Comparative Example 1-2 were immersed in water for 1 hour, and the mass change rate before and after immersion was measured. The specific test method is shown in the national standard GB / T 17431.2-2010. The test results are as follows: Figure 5 shown.

[0096] (6) Sound absorption coefficient and thermal conductivity: The sound absorption performance of Example 1 and Comparative Example 1 was tested using a transfer function sound absorption coefficient test system (BK 4206, Denmark) with a test frequency range of 500 Hz to 6400 Hz. The thermal conductivity of Example 1 and Comparative Example 1 was tested at room temperature using a thermal performance analyzer (Hotdisk TPS2500S, Sweden). The test results are shown in Figure 2. Figure 6 As shown, Figure 6The left side of the middle image shows the comparison data of thermal conductivity measurement, and the right side shows the comparison data of sound absorption coefficient measurement.

[0097] (7) Porosity: Mercury intrusion porosimetry (MIP) was used to characterize the pore structure and test the porosity of Example 1 and Comparative Example 1. The test results are shown in Figure 2. Figure 7 As shown, Figure 7 The left side of the figure shows the comparative data of pore structure characterization, and the right side shows the comparative data of porosity.

[0098] Example 1 showed the best mechanical strength, with a bulk density of 626.77 kg / m 3 , a cylinder compressive strength of 3.27 MPa, and a water absorption rate of 22.81%, all of which meet the requirements of the national standard for lightweight aggregates and their test methods (GB / T17431.2-2010). Furthermore, Example 1 has a thermal conductivity of 0.265 W / (m·K), and its sound absorption band shifts toward higher frequencies (2500-3500 Hz, with a peak sound absorption coefficient of 0.547).

[0099] Depend on Figure 2 It can be obtained that the single particle strength of the full fly ash sample (10:0 group) of Comparative Example 3 is extremely low, and it is difficult to play a skeletal support role in concrete. As the blast furnace slag content increases (from Comparative Example 3 to Comparative Example 1, the blast furnace slag gradually increases), the pore size of the porous spherical particles is refined, the porosity decreases, and the single particle strength increases. On the contrary, as the amount of H2O2 added increases, the pore size of the porous spherical particles is coarsened, the porosity increases, and the single particle strength decreases. Therefore, in order to make the comparison more convincing, and in order to ensure that the lightweight aggregate has high porosity while having good mechanical properties, the uncarbonized 6:4-2.0wt.%, 8:2-1.0wt.% and 10:0-0.6wt.% are selected as Comparative Examples 1-3, and the carbonized 6:4-2.0wt.% is used as Example 1 to compare the data with the comparative example.

[0100] contrast Figure 3It can be obtained that: the cylinder compressive strength of Example 1 is the highest, which is 3.27 MPa, meeting the lightweight aggregate standard GB / T17431.1-2010; although Comparative Example 1 has not undergone accelerated carbonation treatment, the high content of blast furnace slag in Comparative Example 1 improves the hydration degree and density of the porous unburned lightweight aggregate skeleton matrix, so its cylinder compressive strength is higher than that of other comparative examples (Comparative Example 3 is a porous unburned aggregate made of all fly ash, with a low hydration degree and a high porosity), but it is much lower than that of Example 1. This is because in Example 1 of the technical solution of the present invention, which has undergone accelerated carbonation treatment, a large amount of calcium carbonate (calcite) is generated on the pore wall, reducing the pore size and proportion of the foam pores (macroporous pores); at the same time, the generation of calcite fills the defects of the macropores caused by "coarsening-polymerization" during the foaming process, thereby ensuring the integrity of the pore structure. Thereby, the cylinder pressure strength is improved, which proves from the data perspective that the present invention can achieve the improvement of cylinder pressure strength by setting up accelerated carbonation treatment, while the control example does not set up the accelerated carbonation step, which will make the macropores coarse and increase defects, which is not conducive to the improvement of its cylinder pressure strength. At the same time, it also proves that the cylinder pressure strength can be guaranteed by the specific setting of the specific parameters of the present invention.

[0101] contrast Figure 4 It can be obtained that: for bulk density, the bulk density of Example 1 is 626.77 kg / m 3 , meet the lightweight aggregate density grade 700, meet the bulk density ≤1200kg / m in GBT17431.1-2010 3 Compared with Comparative Examples 1-2, the bulk density of Example 1 increased because the accelerated carbonation treatment increased CO2 adsorption and generated calcite, thereby improving the bulk density. This comparison also shows that the ratio of blast furnace slag to fly ash set in the present invention, combined with the subsequent carbonation treatment, can improve the overall bulk density.

[0102] contrast Figure 5The water absorption rate of Example 1 is 22.81%. Compared with Comparative Examples 1-2, the water absorption rate of Example 1 is more compatible with the application of the present invention. For the porous, unfired lightweight aggregate with sound absorption and thermal insulation functions of the present invention, higher water absorption is not necessarily better, nor is lower water absorption necessarily better. GB / T 17431.2-2010 stipulates that the water absorption rate of lightweight aggregate should be less than 10%. However, most studies show that porous aggregates generally have water absorption rates exceeding 10% due to their high porosity. High water absorption rates also exhibit good internal curing advantages when used in concrete. Therefore, the present invention demonstrates a trend of reducing the water absorption rate of porous aggregates by accelerating carbonation for specific applications of the present invention. This is attributed to the filling of calcite and the increase in the proportion of gel pores and transition pores, making the water absorption rate of the present invention more suitable for the specific application of the present invention. Comparative Example 3 has the highest water absorption rate, which is due to the low degree of hydration and the high porosity of the fly ash raw material.

[0103] contrast Figure 6 It can be obtained that the proportion of macropores (≥1000nm) in Example 1 is reduced, and the proportion of gel pores and transition pores is increased (0-100nm). This is because the calcium ion leaching in the gel phase during the accelerated carbonation process causes the gel phase to polymerize and shrink, which increases the proportion of gel pores and transition pores. For macropores, calcite is generated on the pore walls and defects of the macropores, which reduces the proportion of macropores. Through the above comparison, it can be concluded that the proportion of macropores in Comparative Example 1, which does not implement accelerated carbonation treatment, is high, and the cylinder pressure strength is reduced.

[0104] contrast Figure 7 It can be obtained that: compared with comparative example 1 (thermal conductivity 0.264W·(m / K)), the thermal conductivity of embodiment 1 with accelerated carbonation treatment is maintained at 0.265W·(m / K), which shows that the porous unburned lightweight aggregate has good thermal insulation performance, which is conducive to its application in lightweight aggregate concrete. Compared with comparative example 1, the sound absorption band of embodiment 1 with accelerated carbonation treatment shifts from medium frequency (sound absorption coefficient 0.638) to high frequency (sound absorption coefficient 0.547), which is due to the increase in the proportion of gel pores and transition pores. The porous unburned lightweight aggregate that has not undergone accelerated carbonation can absorb medium-frequency noise, and the porous unburned lightweight aggregate with accelerated carbonation treatment can absorb high-frequency noise, which broadens its noise absorption band. In short, compared with traditional unburned lightweight aggregate, the porous unburned lightweight aggregate produced by this invention has good thermal insulation and sound absorption properties.

[0105] The technical principles and examples of the present invention are described above in conjunction with specific embodiments. The above-mentioned embodiments and comparative examples of the present invention are all examples and do not limit the scope of protection of the technical solution. The technical effects that are not compared can be clearly described through the textual description of the technical effects, and do not mean that the invention is low. These descriptions are only for explaining the principles and examples of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations here, those skilled in the art can think of other specific embodiments of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions, characterized in that: The steps include: S1. Adding water to the alkaline salt and / or base, stirring thoroughly and dissolving in water to obtain an activator; S2. Drying the typical silicoaluminous solid waste and the high-calcium solid waste to a constant weight, and then sieving to obtain small-sized particles of the typical silicoaluminous solid waste and the high-calcium solid waste, and then mixing the typical silicoaluminous solid waste and the high-calcium solid waste in a weight ratio of (10-4):(0-6) to obtain a solid waste raw material; S3, adding 30-60 wt.% of the activator obtained in S1 to the solid waste raw material obtained in S2, and stirring thoroughly to obtain an alkali-activated slurry; S4, adding 0.5-4.0 wt.% of a pore-forming agent to the alkali-activated slurry obtained in S3 and stirring to obtain a pre-foamed slurry; S5, injecting the pre-foamed slurry obtained in S4 into the mold, and then placing the mold in a curing box for curing and solidification; S6. Demolding the material obtained after curing in S5, and then placing the demolded particles in a carbonization box for carbonization treatment to obtain porous unburned lightweight aggregate.

2. The method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions according to claim 1, characterized in that: The alkaline salt and / or base is industrial grade sodium silicate and sodium hydroxide mixed in a weight ratio of (29-33): (3-7).

3. The method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions according to claim 1 or 2, characterized in that: In step S1, the alkaline salt and / or base is added to water, fully stirred and dissolved in water. Specifically, the alkaline salt and / or base is added to deionized water at 80-100° C., and then fully stirred at the same temperature until it becomes clear. The ratio of the alkaline salt and / or base to the deionized water is (1-3): (0.5-2); the resulting activator modulus is 1.2-1.

6.

4. The method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions according to claim 1, characterized in that: In step S2, the drying temperature of typical silicon-aluminum solid waste and high-calcium solid waste is 100-110° C., and the drying time is 12-48 hours; The typical silicon-aluminum solid waste and high-calcium solid waste with small particle size are typical silicon-aluminum solid waste and high-calcium solid waste with particle size less than 0.075 mm; The typical siliceous and aluminous solid waste is fly ash and / or coal gangue; the high-calcium solid waste is blast furnace slag, steel slag and / or sintering red mud.

5. The method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions according to claim 1, characterized in that: The typical silicoaluminous solid waste and high-calcium solid waste in step S2 are replaced by a single high-calcium solid waste, wherein the high-calcium solid waste is blast furnace slag, steel slag and / or sintering red mud.

6. The method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions according to claim 1, characterized in that: In step S3, the stirring speed for sufficient stirring is 200 to 500 rpm / min, and the stirring time is 2 to 5 minutes; In step S4, the pore-forming agent is hydrogen peroxide (H2O2) with a volume fraction of 30%, the stirring speed is 200-400 rpm / min, and the stirring time is 1-3 minutes.

7. The method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions according to claim 1, characterized in that: In step S5, the mold is a spherical mold, and the spherical mold is a 27-link mold with a diameter of 10 to 13 mm; the curing temperature of the curing box is 60 to 80° C., and the curing time is 10 to 13 hours.

8. The method for preparing porous unburned lightweight aggregate with sound absorption and heat insulation functions according to claim 1 or 7, characterized in that: In step S6, the particles obtained after demoulding are spherical particles, and the carbonization treatment includes the following steps: I. Place the obtained spherical particles in a tray and set the temperature in the carbonization box to 25-40°C and the humidity to 70-100% RH; II. Place the tray in a carbonization box and introduce CO2 gas into the carbonization box. When the CO2 concentration in the carbonization box reaches 20-40%, stop the ventilation and maintain the carbonization box at normal pressure. The spherical particles are accelerated to carbonate in the carbonization box for 8-16 hours. III. After the treatment time is over, the tray containing the spherical particles is taken out to complete the accelerated carbonation treatment.

9. A porous, unburned lightweight aggregate with sound absorption and heat preservation functions, characterized in that: The porous unburned lightweight aggregate with sound absorption and heat insulation functions is prepared by the preparation method according to any one of claims 1 to 9.

10. The porous unburned lightweight aggregate with sound absorption and heat insulation functions according to claim 9, characterized in that: The porous unburned lightweight aggregate has a cylinder compressive strength of 2.2-3.56 MPa and a bulk density of 580-635 kg / m 3 The water absorption rate is 20-27%, the thermal conductivity is 0.25-0.28W / (m·K), the sound absorption band shifts to the high frequency of 2500-3500Hz, and the peak sound absorption coefficient is 0.5-0.6.

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