Lightweight high-strength solid waste-based ceramsite aggregate as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of building material preparation, and discloses lightweight high-strength solid waste-based ceramsite aggregate as well as a preparation method and application thereof. The preparation raw materials of the lightweight high-strength solid waste-based ceramsite comprise the iron tailings, the municipal sludge and the granite sawdust, and the lightweight high-strength solid waste-based ceramsite has the characteristics of high mechanical strength, low volume density, high closed porosity, low water absorption, strong corrosion resistance and moderate particle size. The ceramsite is prepared from the tailings, the granite sawdust and the municipal sludge, so that environmental damage and potential safety hazards caused by solid waste accumulation can be reduced, the ceramsite is used as concrete lightweight aggregate for buildings, solid waste resources can be promoted to be efficiently converted into green building materials, large-scale application of low-carbon scenes such as prefabricated buildings and sponge cities is assisted, and the method has a wide application prospect. Meanwhile, the value of a circular economy industry chain is improved. The ceramsite lightweight aggregate prepared by the method disclosed by the invention has important significance in the fields of high value-added utilization of bulk solid wastes and green and high-performance concrete materials.

Description

Technical Field

[0001] The present invention relates to the technical field of building material preparation, and in particular to a lightweight and high-strength solid waste-based ceramsite aggregate, and a preparation method and application thereof. Background Art

[0002] As the world's most widely used civil engineering material, concrete's technological development has entered a stage of high-performance and intelligent development. The concrete industry has achieved breakthroughs in high-performance concrete, lightweight concrete, and self-healing concrete, and has widely applied them in major projects such as high-speed railways and super-high-rise buildings. Currently, the concrete industry is accelerating its greening process, reducing resource consumption through solid waste utilization and promoting low-carbon production processes. The application of intelligent production lines and big data analysis technologies has improved production efficiency and quality management. Among them, ceramsite concrete, a green concrete that uses artificial lightweight aggregate instead of traditional stone, has been favored by scholars for its advantages such as light weight and high strength, excellent thermal insulation, outstanding seismic and fire resistance, and excellent durability and impermeability.

[0003] However, the existing ceramsite lightweight aggregate has the following problems: First, the use of natural clay and shale as the main raw materials is not in line with the current concept of sustainable development; second, the technology for preparing ceramsite lightweight aggregate using solid waste is weak, resulting in high water absorption of finished ceramsite products; third, there is a contradiction between compressive strength and density. The cylinder compressive strength of clay ceramsite is only 2.5 to 4.0 MPa, while high-strength ceramsite lightweight aggregate often has a relatively large density. Summary of the Invention

[0004] The purpose of the present invention is to provide a lightweight and high-strength solid waste-based ceramsite aggregate and its preparation method and application, so as to solve the problems of high raw material cost, high density, low compressive strength, high water absorption and poor corrosion resistance of existing ceramsite aggregate.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a lightweight and high-strength solid waste-based ceramsite aggregate, comprising the following raw materials in parts by mass:

[0007] 60-76 parts of iron ore tailings, 10-23 parts of municipal sludge, 13-20 parts of granite sawdust, and 5-10 parts of polyvinyl alcohol solution.

[0008] Furthermore, in the light-weight high-strength solid waste-based ceramsite aggregate, the iron tailings contain SiO2 ≥ 35 wt%, and CaO ≥ 20 wt%;

[0009] The average particle size of the iron tailings is ≤74 μm.

[0010] Further, in the lightweight high-strength solid waste-based ceramsite aggregate, the organic matter in the municipal sludge is ≥ 50wt%, SiO2 is ≥ 15wt%, and Al2O3 is ≥ 7wt%.

[0011] The average particle size of the municipal sludge is ≤ 74μm.

[0012] Further, in the lightweight high-strength solid waste-based ceramsite aggregate, the SiO2 in the granite sawdust is ≥ 65wt%, Al2O3 is ≥ 15wt%, and Na2O is ≥ 3wt%.

[0013] The average particle size of the granite sawdust is ≤ 74μm.

[0014] Further, in the lightweight high-strength solid waste-based ceramsite aggregate, the mass concentration of the polyvinyl alcohol solution is 9-13%.

[0015] The application further provides a preparation method of the lightweight high-strength solid waste-based ceramsite aggregate.

[0016] (1) mixing part of the iron tailings, the municipal sludge and part of the polyvinyl alcohol solution, and performing first calcination to obtain green balls;

[0017] (2) mixing the green balls with the remaining iron tailings, the granite sawdust and the remaining polyvinyl alcohol solution to obtain composite green balls; and performing second calcination on the composite green balls to obtain the lightweight high-strength solid waste-based ceramsite aggregate.

[0018] Further, in the preparation method of the lightweight high-strength solid waste-based ceramsite aggregate, the first calcination in step (1) has the conditions of: a calcination temperature of 150-190℃, a holding time of 60-120min, and a heating rate of 2-5℃ / min to the required calcination temperature.

[0019] Further, in the preparation method of the lightweight high-strength solid waste-based ceramsite aggregate, the second calcination in step (2) has the conditions of: a calcination temperature of 1100-1200℃, a holding time of 30-90min, and a heating rate of 2-5℃ / min to the required calcination temperature.

[0020] Further, in the preparation method of the lightweight high-strength solid waste-based ceramsite aggregate, the particle size of the green balls in step (1) is 3-9mm.

[0021] The particle size of the composite green balls in step (2) is 5-11mm.

[0022] The application further provides application of the lightweight high-strength solid waste-based ceramsite aggregate in building materials.

[0023] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) The raw materials of the present invention include iron tailings CaO ≥ 20 wt%, municipal sludge organic matter ≥ 50 wt%, and a high content of fluxing metal oxides in the mixed raw materials. Furthermore, a binder, fully alcoholyzed polyvinyl alcohol, is added. During the calcination process, a large amount of burnout occurs, resulting in the formation of numerous micron- and nano-scale pores within the ceramsite, thereby reducing the density of the ceramsite, increasing the total porosity, and roughening the surface. Furthermore, granite sawdust contains SiO₂ ≥ 65 wt%, and iron tailings contain SiO₂ ≥ 35 wt%. High-temperature calcination forms a small amount of molten phase, which adheres to the solid phase surface after cooling to form a strong skeleton, thereby increasing the strength of the ceramsite and reducing its hydrochloric acid solubility.

[0025] (2) The present invention adopts a wrapping form, wherein the inner layer is mainly a raw material ball mixed with municipal sludge and iron tailings, and the outer layer is mainly a shell mixed with granite sawdust and iron tailings. In the lightweight and high-strength solid waste-based ceramsite prepared by the present invention, the raw materials of the inner layer mainly contain CaO, SiO2, Al2O3, Fe2O3 and organic matter. During the heating process, a large amount of organic matter is burned away and releases gases such as CO2 and H2O, forming a large number of in-situ pores, which significantly reduces the bulk density of the ceramsite aggregate. In addition, during the firing process, the sludge carbon remaining in the municipal sludge reduces the Fe2O3 in the iron tailings, and accompanied by the release of gas, it causes expansion to form a porous structure, further reducing the bulk density of the ceramsite aggregate. In addition, in the presence of Fe2O3 as a flux, SiO2 and Al2O3 form high-strength mullite and anorthite, which provide strength for the inner layer structure of the ceramsite aggregate.

[0026] (3) In the lightweight, high-strength solid waste-based ceramsite prepared by the present invention, the raw materials for the outer layer mainly contain CaO, SiO2, Al2O3, and Fe2O3. During the calcination process, components such as quartz (SiO2) and feldspar (Al2O3·SiO2) melt to form a glass phase. After cooling, a dense shell phase is formed, which adheres to the surface of the inner layer. The bonding effect of the glass body strengthens the bonding between the particles. Among them, the sintering process generates mullite crystals. The high strength, density, and thermal stability of the outer layer formed by them significantly improve the overall strength and corrosion resistance of the ceramsite aggregate.

[0027] (4) In the lightweight, high-strength solid waste-based ceramsite aggregate prepared by the present invention, the SiO2 content in the raw materials of the outer layer is greater than that in the inner layer. This makes the Fe2O3 in the iron tailings have a more significant effect on the outer layer when playing a fluxing role. The liquid phase in the outer layer is more than that in the inner layer and appears earlier than the inner layer. As a result, after cooling, only a small amount of glass phase is produced in the inner layer, and a large amount of glass phase is produced in the outer layer, which is evenly wrapped on the surface of the inner layer, converting the open pores of the inner layer into closed pores, forming a dense and hard shell, reducing the overall water absorption rate, improving the overall corrosion resistance, and retaining the closed pore structure of the inner layer. While improving the strength, the low bulk density of the aggregate is retained.

[0028] (5) The bulk density of the ceramsite provided by the present invention is 0.65 to 0.92 g / cm 3 , strength of 26.37-35.83 MPa, cylinder pressure strength of 33.81-46.07 MPa, total porosity of 56-78%, water absorption of 0.42-1.56%, and hydrochloric acid solubility of 0.14-0.37%. The lightweight, high-strength solid waste-based ceramsite aggregate prepared by the present invention has the advantages of low bulk density, high strength, and low hydrochloric acid solubility. The rough surface helps to form a mechanical bite effect in concrete, thereby improving the strength of ceramsite aggregate concrete. The raw materials used in the present invention are iron tailings, municipal sludge, and granite sawdust, all of which are large-scale solid wastes. This fully realizes the comprehensive utilization of iron tailings, municipal sludge, and granite sawdust resources, has the advantages of high resource utilization rate and low production cost, and solves the problem of large accumulation of iron tailings, municipal sludge, and granite sawdust resources. At the same time, the process of the present invention solidifies the heavy metals in the raw materials, and the finished ceramsite aggregate can be directly incorporated into concrete, achieving the purpose of solid waste utilization and solving the problem of large accumulation of iron tailings and municipal sludge. DETAILED DESCRIPTION

[0029] The present invention provides a lightweight and high-strength solid waste-based ceramsite aggregate, comprising the following raw materials in parts by mass:

[0030] 60-76 parts of iron ore tailings, 10-23 parts of municipal sludge, 13-20 parts of granite sawdust, and 5-10 parts of polyvinyl alcohol solution.

[0031] In the present invention, the mass fraction of the iron tailings is preferably 62 to 74 parts, more preferably 65 to 70 parts, and even more preferably 66 to 69 parts.

[0032] In the present invention, the mass fraction of the municipal sludge is preferably 12 to 22 parts, more preferably 14 to 20 parts, and even more preferably 16 to 18 parts.

[0033] In the present invention, the mass fraction of the granite sawdust is preferably 13.5 to 16.5 parts, more preferably 13 to 16 parts, and even more preferably 14 to 15 parts.

[0034] In the present invention, the weight percentage of the polyvinyl alcohol solution is preferably 5.5 to 9.5 parts, more preferably 6 to 9 parts, and even more preferably 7 to 8 parts.

[0035] In the present invention, in the iron tailings, SiO2≥35wt%, preferably ≥37wt%, further preferably ≥39wt%, more preferably ≥41wt%; CaO≥20wt%, preferably ≥22wt%, further preferably ≥24wt%, more preferably ≥26wt%.

[0036] In the present invention, the average particle size of the iron tailings is preferably ≤74 μm, more preferably ≤72 μm, and even more preferably ≤70 μm.

[0037] In the present invention, in the municipal sludge, the organic matter is ≥50wt%, preferably ≥53wt%, further preferably ≥56wt%, more preferably ≥59wt%; SiO2 is ≥15wt%, preferably ≥16wt%, further preferably ≥17wt%, more preferably ≥18wt%; Al2O3 is ≥7wt%, preferably ≥7.5wt%, further preferably ≥8wt%, more preferably ≥8.5wt%.

[0038] In the present invention, the average particle size of the municipal sludge is preferably ≤74 μm, more preferably ≤72 μm, and even more preferably ≤70 μm.

[0039] In the present invention, in the granite sawdust, SiO2≥65wt%, preferably ≥67wt%, further preferably ≥69wt%, more preferably ≥71wt%; Al2O3≥15wt%, preferably ≥16wt%, further preferably ≥17wt%, more preferably ≥18wt%; Na2O≥3wt%, preferably ≥4wt%, further preferably ≥5wt%, more preferably ≥6wt%.

[0040] In the present invention, the average particle size of the granite sawdust is preferably ≤74 μm, more preferably ≤72 μm, and even more preferably ≤70 μm.

[0041] In the present invention, the mass concentration of the polyvinyl alcohol solution is 9 to 13%, preferably 9.5 to 12.5%, more preferably 10 to 12%, and even more preferably 10.5 to 11.5%.

[0042] The present invention also provides a method for preparing lightweight and high-strength solid waste-based ceramsite aggregate, comprising the following steps:

[0043] (1) mixing part of the iron ore tailings, municipal sludge, and part of the polyvinyl alcohol solution, and performing a first calcination to obtain raw material balls;

[0044] (2) mixing the raw material balls with the remaining iron tailings, granite sawdust, and the remaining polyvinyl alcohol solution to obtain composite raw material balls; and performing a second calcination on the composite raw material balls to obtain lightweight and high-strength solid waste-based ceramsite aggregate.

[0045] In the present invention, the specific steps of the mixing in step (1) are preferably: firstly, a portion of the iron tailings and the municipal sludge are mixed and placed in a granulator, and then a portion of the polyvinyl alcohol solution is added in a spraying manner while the mixture is rotating.

[0046] In the present invention, in step (1), before the first calcination, the process preferably further comprises: drying, and then placing the dried pellets in a calcining furnace.

[0047] In the present invention, the drying temperature is preferably 100-110°C, more preferably 102-108°C, and even more preferably 104-106°C.

[0048] In the present invention, the conditions for the first calcination in step (1) include: the calcination temperature is preferably 150-190°C, more preferably 160-180°C, and more preferably 165-175°C; the holding time is preferably 60-120 min, more preferably 70-110 min, and more preferably 80-100 min; the rate of heating to the desired calcination temperature is preferably 2-5°C / min, more preferably 2.5-4.5°C / min, and more preferably 3-4°C / min.

[0049] In the present invention, the particle size of the raw balls in step (1) is preferably 3 to 9 mm, more preferably 4 to 8 mm, and even more preferably 5 to 7 mm.

[0050] In the present invention, the specific steps of mixing in step (2) are preferably: after the raw balls are cooled, they are placed in a granulator, and the mixed powder of the remaining iron tailings and granite sawdust is added while rotating, and the remaining polyvinyl alcohol solution is added in a spraying manner.

[0051] In the present invention, the particle size of the composite raw ball in step (2) is 5 to 11 mm, preferably 5.5 to 10.5 mm, more preferably 6 to 10 mm, and even more preferably 6.5 to 9.5 mm.

[0052] In the present invention, in step (3), the composite raw ball preferably further comprises drying before the second calcination, and then the dried composite raw ball is placed in a calcining furnace for preheating.

[0053] In the present invention, the drying temperature is preferably 100-110°C, more preferably 102-108°C, and even more preferably 104-106°C.

[0054] In the present invention, the preheating temperature is preferably 350-450°C, more preferably 370-430°C, and more preferably 390-410°C; the preheating holding time is preferably 5-35 minutes, more preferably 10-30 minutes, and more preferably 15-25 minutes.

[0055] In the present invention, the conditions for the second calcination in step (2) include: the calcination temperature is preferably 1100-1200°C, more preferably 1120-1180°C, and more preferably 1140-1160°C; the holding time is preferably 30-90 min, more preferably 40-80 min, and more preferably 50-70 min; the rate of heating to the desired calcination temperature is preferably 2-5°C / min, more preferably 2.5-4.5°C / min, and more preferably 3-4°C / min.

[0056] The present invention also provides an application of lightweight and high-strength solid waste-based ceramsite aggregate in building materials.

[0057] In the present invention, the application method is not limited and any method well known to those skilled in the art may be used.

[0058] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0059] Example 1

[0060] This embodiment provides a method for preparing lightweight and high-strength solid waste-based ceramsite aggregate, comprising the following steps:

[0061] (1) 74 parts of iron tailings, 10 parts of municipal sludge, 16 parts of granite sawdust, and 9 parts of polyvinyl alcohol solution; wherein the iron tailings raw material contains SiO2 45wt%, CaO 28wt%, and an average particle size of 39μm; the municipal sludge raw material contains organic matter 50wt%, SiO2 18wt%, Al2O3 8wt%, and an average particle size of 32μm; the granite sawdust raw material contains SiO2 73wt%, Al2O3 17wt%, Na2O 3wt%, and an average particle size of 35μm;

[0062] The 38 parts of iron tailings and municipal sludge were mixed and placed in a granulator, 4.5 parts of a polyvinyl alcohol solution (Tianjin Hua Sheng, 1799) with a mass concentration of 13% was added in a spraying manner under rotating conditions to obtain material balls; the material balls were placed in an oven and dried at a temperature of 105°C, and then the dried green balls were heated to 185°C at a heating rate of 3.5°C / min, calcined for 120 min, and cooled to obtain green balls with a particle size of 6 mm;

[0063] (2) The green balls were placed in a granulator, 36 parts of iron tailings and granite sawdust mixed powder were added under rotating conditions, and 4.5 parts of a polyvinyl alcohol solution with a mass concentration of 13% was added in a spraying manner to obtain composite green balls with a particle size of 8 mm; the composite green balls were placed in an oven and dried at a temperature of 105°C, and then the dried composite green balls were placed in a calcining furnace at a temperature of 400°C for preheating for 20 min, and then heated to 1200°C at a heating rate of 3.5°C / min, calcined for 90 min to obtain lightweight high-strength solid waste-based ceramsite aggregates.

[0064] It was tested that the volume density of the ceramsite aggregate obtained in Example 1 was 0.92 g / cm 3 , the strength was 35.83 MPa, the cylinder compressive strength was 46.07 MPa, the total porosity was 56%, the water absorption rate was 0.42%, and the hydrochloric acid soluble rate was 0.14%.

[0065] Example 2

[0066] The present embodiment provides a preparation method of lightweight high-strength solid waste-based ceramsite aggregates, comprising the following steps:

[0067] (1) 72 parts of iron tailings, 13 parts of municipal sludge, 15 parts of granite sawdust, and 7 parts of polyvinyl alcohol solution; wherein the iron tailings raw material contains SiO2 41wt%, CaO 26wt%, and the average particle size is 39μm; the municipal sludge raw material contains organic matter 53wt%, SiO2 18wt%, Al2O3 9wt%, and the average particle size is 36μm; the granite sawdust raw material contains SiO2 72wt%, Al2O3 16wt%, Na2O 3wt%, and the average particle size is 35μm;

[0068] The 36 parts of iron tailings and municipal sludge were mixed and placed in a granulator, 3.5 parts of a polyvinyl alcohol solution (Tianjin Hua Sheng, 1799) with a mass concentration of 12% was added in a spraying manner under rotating conditions to obtain material balls; the material balls were placed in an oven and dried at a temperature of 105°C, and then the dried green balls were heated to 165°C at a heating rate of 3.5°C / min, calcined for 120 min, and cooled to obtain green balls with a particle size of 6 mm;

[0069] (2) The raw material balls were placed in a granulator, and 36 parts of a mixed powder of iron tailings and granite sawdust were added under rotating conditions, and 3.5 parts of a polyvinyl alcohol solution with a mass concentration of 12% was added by spraying to obtain composite raw material balls with a particle size of 8 mm; the composite raw material balls were placed in an oven and dried at a temperature of 105°C, and then the dried composite raw material balls were placed in a calcining furnace at a temperature of 400°C for preheating for 20 minutes, and then the temperature was increased to 1150°C at a heating rate of 3.5°C / min, and calcined for 60 minutes to obtain lightweight and high-strength solid waste-based ceramsite aggregate.

[0070] The bulk density of the ceramsite aggregate obtained in Example 2 was 0.81 g / cm 3 , strength is 34.08MPa, cylinder pressure strength is 42.51MPa, total porosity is 63%, water absorption rate is 0.74%, and hydrochloric acid solubility is 0.21%.

[0071] Example 3

[0072] This embodiment provides a method for preparing lightweight and high-strength solid waste-based ceramsite aggregate, comprising the following steps:

[0073] (1) 66 parts of iron tailings, 19 parts of municipal sludge, 15 parts of granite sawdust, and 8 parts of polyvinyl alcohol solution; wherein the iron tailings raw material contains SiO2 41wt%, CaO 26wt%, and an average particle size of 36μm; the municipal sludge raw material contains organic matter 56wt%, SiO2 17wt%, Al2O3 9wt%, and an average particle size of 36μm; the granite sawdust raw material contains SiO2 70wt%, Al2O3 16wt%, Na2O 3wt%, and an average particle size of 42μm;

[0074] 30 parts of iron tailings and municipal sludge were mixed and placed in a granulator. 4 parts of a 12% polyvinyl alcohol solution (Tianjin Huasheng, 1799) was added by spraying while the granulator was rotating to obtain pellets. The pellets were dried in an oven at 105°C. The dried pellets were then heated to 175°C at a heating rate of 3.5°C / min, calcined for 120 minutes, and cooled to obtain pellets with a particle size of 6 mm.

[0075] (2) The raw material balls were placed in a granulator, and 36 parts of a mixed powder of iron tailings and granite sawdust were added under rotating conditions, and 4 parts of a polyvinyl alcohol solution with a mass concentration of 12% was added by spraying to obtain composite raw material balls with a particle size of 8 mm; the composite raw material balls were placed in an oven and dried at a temperature of 105°C, and then the dried raw material balls were placed in a calcining furnace at a temperature of 400°C for preheating for 20 minutes, and then the temperature was increased to 1130°C at a heating rate of 3.5°C / min, and calcined for 60 minutes to obtain lightweight and high-strength solid waste-based ceramsite aggregate.

[0076] The bulk density of the ceramsite aggregate obtained in Example 3 was 0.74 g / cm 3 , strength is 28.89MPa, cylinder pressure strength is 38.68MPa, total porosity is 72%, water absorption rate is 1.09%, and hydrochloric acid solubility is 0.29%.

[0077] Example 4

[0078] This embodiment provides a method for preparing lightweight and high-strength solid waste-based ceramsite aggregate, comprising the following steps:

[0079] (1) 64 parts of iron tailings, 23 parts of municipal sludge, 13 parts of granite sawdust, and 6 parts of polyvinyl alcohol solution; wherein the iron tailings raw material contains 41 wt% of SiO2, 26 wt% of CaO, and an average particle size of 39 μm; the municipal sludge raw material contains 59 wt% of organic matter, 18 wt% of SiO2, and 39 wt% of Al2O3, and an average particle size of 36 μm; and the granite sawdust raw material contains 69 wt% of SiO2, 16 wt% of Al2O3, and 3 wt% of Na2O, and an average particle size of 42 μm;

[0080] 32 parts of iron tailings and municipal sludge were mixed and placed in a granulator. 3 parts of 11% polyvinyl alcohol solution (Tianjin Huasheng, 1799) was added by spraying while the granulator was rotating to obtain pellets. The pellets were placed in an oven and dried at 105°C. The dried pellets were then heated to 170°C at a heating rate of 3.5°C / min, calcined for 120 minutes, and cooled to obtain pellets with a particle size of 6 mm.

[0081] (2) The raw material balls were placed in a granulator, and 32 parts of a mixed powder of iron tailings and granite sawdust were added under rotating conditions, and 3 parts of a polyvinyl alcohol solution with a mass concentration of 11% was added by spraying to obtain composite raw material balls with a particle size of 8 mm; the composite raw material balls were placed in an oven and dried at a temperature of 105°C, and then the dried composite raw material balls were placed in a calcining furnace at a temperature of 400°C for preheating for 20 minutes, and then the temperature was increased to 1100°C at a heating rate of 3.5°C / min, and calcined for 60 minutes to obtain lightweight and high-strength solid waste-based ceramsite aggregate.

[0082] The bulk density of the ceramsite aggregate obtained in Example 4 was tested to be 0.65 g / cm 3 , strength is 26.37MPa, cylinder pressure strength is 33.81MPa, total porosity is 78%, water absorption rate is 1.56%, and hydrochloric acid solubility is 0.37%.

[0083] Performance Testing

[0084] The lightweight, high-strength solid waste-based ceramsite aggregate obtained in Examples 1 to 4 was soaked in water for 24 hours to allow it to absorb water to saturation; after removal, it was naturally dried to a "saturated surface dry" state. The pretreated lightweight, high-strength solid waste-based ceramsite aggregate was dry-mixed with cement, admixtures, sand, etc. for 2 minutes until uniform, wherein the ceramsite aggregate was added in an amount of 50wt%. Water was added in two steps (first adding 60% of the total water volume, then adding the remaining water, water reducer, and anti-segregation material), and the stirring time was 90s. The mixture was poured into a 150×150×150mm mold at a temperature of 20°C and a humidity of ≥95%, and the curing period was 28 days. The compressive strength and apparent density of the concrete samples were measured according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete" and GB / T50082-2024 "Standard for Test Methods of Long-term Performance and Durability of Concrete". The results are shown in Table 1.

[0085] Table 1. Compressive strength and apparent density of ceramsite aggregate concrete samples

[0086] Case Compressive strength / MPa <![CDATA[表观密度 / kg / m 3 ]]> Example 1 49.3 1923 Example 2 47.9 1798 Example 3 44.6 1614 Example 4 43.5 1462

[0087] As can be seen from Table 1, the lightweight and high-strength solid waste-based ceramsite provided by the present invention plays a role in providing strength and reducing density in concrete.

[0088] From the above examples, it can be seen that the present invention provides a lightweight and high-strength solid waste-based ceramsite with a bulk density of 0.65 to 0.92 g / cm 3 , strength is 26.37~35.83MPa, cylinder pressure strength is 33.81~46.07MPa, total porosity is 56~78%, water absorption is 0.42~1.56%, hydrochloric acid solubility is 0.14~0.37%, and it has the advantages of high mechanical strength, low bulk density, high closed porosity, low water absorption, low hydrochloric acid solubility, rough surface for easy adhesion, strong corrosion resistance, and moderate particle size. Its preparation raw materials include iron tailings, urban sludge, and granite sawdust. Tailings are waste residues produced after mineral mining, granite sawdust is waste chips produced during stone processing, and urban sludge refers to muddy or semi-solid wastes produced during urban construction, public facilities maintenance, and urban water treatment. This method uses tailings, granite sawdust, and municipal sludge to prepare ceramsite, which can reduce the environmental damage and safety hazards caused by solid waste accumulation. Using the prepared ceramsite as lightweight aggregate for building concrete can promote the efficient conversion of solid waste resources into green building materials, aiding the large-scale application of low-carbon scenarios such as prefabricated buildings and sponge cities, while also enhancing the value of the circular economy industry chain. This method for preparing ceramsite lightweight aggregate has important implications for the high-value-added utilization of bulk solid waste and the green, high-performance development of concrete materials.

[0089] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A lightweight and high-strength solid waste-based ceramsite aggregate, characterized in that: Contains the following raw materials in parts by weight: 60-76 parts of iron ore tailings, 10-23 parts of municipal sludge, 13-20 parts of granite sawdust, and 5-10 parts of polyvinyl alcohol solution.

2. The lightweight and high-strength solid waste-based ceramsite aggregate according to claim 1, characterized in that: In the iron tailings, SiO2≥35wt%, CaO≥20wt%; The average particle size of the iron tailings is ≤74 μm.

3. The lightweight and high-strength solid waste-based ceramsite aggregate according to claim 2, characterized in that: In the municipal sludge, organic matter ≥50wt%, SiO2 ≥15wt%, Al2O3 ≥7wt%; The average particle size of the municipal sludge is ≤74 μm.

4. The lightweight and high-strength solid waste-based ceramsite aggregate according to any one of claims 1 to 3, characterized in that: In the granite sawdust, SiO2≥65wt%, Al2O3≥15wt%, and Na2O≥3wt%; The average particle size of the granite sawdust is ≤74 μm.

5. The lightweight and high-strength solid waste-based ceramsite aggregate according to claim 4, characterized in that: The mass concentration of the polyvinyl alcohol solution is 9-13%.

6. The method for preparing a lightweight and high-strength solid waste-based ceramsite aggregate according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) mixing part of the iron ore tailings, municipal sludge, and part of the polyvinyl alcohol solution, and performing a first calcination to obtain raw material balls; (2) mixing the raw material balls with the remaining iron tailings, granite sawdust, and the remaining polyvinyl alcohol solution to obtain composite raw material balls; and performing a second calcination on the composite raw material balls to obtain lightweight and high-strength solid waste-based ceramsite aggregate.

7. The method for preparing a lightweight and high-strength solid waste-based ceramsite aggregate according to claim 6, characterized in that: The conditions for the first calcination in step (1) include: a calcination temperature of 150 to 190° C., a holding time of 60 to 120 minutes, and a heating rate to the desired calcination temperature of 2 to 5° C. / min.

8. The method for preparing a lightweight and high-strength solid waste-based ceramsite aggregate according to claim 6, characterized in that: The conditions for the second calcination in step (2) include: a calcination temperature of 1100-1200° C., a holding time of 30-90 min, and a heating rate to the desired calcination temperature of 2-5° C. / min.

9. The method for preparing a lightweight and high-strength solid waste-based ceramsite aggregate according to any one of claims 6 to 8, characterized in that: The particle size of the raw material balls in step (1) is 3 to 9 mm; The particle size of the composite raw material balls in step (2) is 5 to 11 mm.

10. Use of the lightweight and high-strength solid waste-based ceramsite aggregate according to any one of claims 1 to 5 or the lightweight and high-strength solid waste-based ceramsite aggregate prepared by the preparation method of the lightweight and high-strength solid waste-based ceramsite aggregate according to any one of claims 6 to 9 in building materials.