Sandstone powder-based composite material and preparation method thereof

Abstract

The invention relates to a sandstone powder-based composite material and a preparation method thereof. The composite material comprises the following raw materials in parts by mass: 100 parts of natural rock minerals, 16-32 parts of water glass, 2-8 parts of a nano material and 0-6.23 parts of sodium hydroxide. Wherein in the natural rock minerals, the mass fraction of quartz minerals is 35-50%, the mass fraction of feldspar minerals is 30-40%, and the mass fraction of clay minerals is 10-20%; the mesh number of the natural rock mineral is 60 to 1000; and the modulus of the water glass is 3.0-3.3. The waste natural rock mineral powder is used as the only inorganic raw material, and the low-cost and high-strength material is prepared through gradation design, compact compaction and high-temperature cementation. And a feasible thought is provided for comprehensive utilization of waste rock mineral powder and development of inorganic building materials.

Description

Technical Field

[0001] The invention relates to the technical field of stone solid waste treatment, in particular to a sandstone powder-based composite material and a preparation method thereof. Background Art

[0002] The stone industry has developed rapidly in recent years. However, a large amount of stone waste is generated during the mining and processing of stone. With the continuous expansion of the scale of the stone industry, the contradiction between industrial development and resource conservation and environmental protection has become increasingly acute. In the mining process, the average utilization rate of stone is only about 35%. Most of the resources have become waste in the form of scraps, stone powder, stone slurry, etc. during the mining and processing process, causing great waste of non-renewable resources. In order to make full use of natural rock mineral materials, researchers at home and abroad are committed to exploring the integration of building materials and stone waste, aiming to promote the green development of the economy and achieve sustainable development goals.

[0003] In recent years, there are three main methods for recycling waste natural rock mineral powder: (1) as an admixture for cement-based materials; (2) using binders to prepare artificial stone materials; (3) using a pressing and sintering process to prepare brick materials. However, due to the low volcanic ash activity of waste natural rock mineral materials, their cement replacement rate is limited, and they cannot be fully utilized, and the maintenance cycle is long. Artificial stone materials usually use inorganic or organic binders and need to be vibrated and formed under vacuum. The preparation of sintered bricks is currently a relatively mature and stable process for recycling natural rock mineral powders. The usual preparation method for sintered bricks is to evenly mix rock powder with other binders to prepare a mixture, apply a certain molding pressure to it to form a block, and then complete the preparation through high-temperature calcination at 900-1100°C. In order to improve the mechanical properties of sintered bricks, some scholars use higher firing temperatures, higher molding pressures (>20MPa) or more complex processes to prepare bricks during the production process. Such methods consume a lot of energy and have high requirements for pressurization conditions, which is not conducive to low carbon and sustainable development. Summary of the invention

[0004] The purpose of the present invention is to provide a high-strength sandstone powder-based composite material which can be obtained at a relatively low temperature and with low energy consumption, and a preparation method thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a sandstone powder-based composite material, wherein the raw materials of the composite material are as follows by weight: 100 parts of natural rock minerals, 16-32 parts of water glass, 2-8 parts of nanomaterials, and 0-6.23 parts of sodium hydroxide;

[0007] Among them, the mass fraction of quartz minerals in natural rock minerals is 35-50%, the mass fraction of feldspar minerals is 30-40%, and the mass fraction of clay minerals is 10-20%;

[0008] The mesh number of the natural rock mineral is 60-1000 meshes; the modulus of the water glass is 3.0-3.3.

[0009] The particle sizes of the natural rock minerals are divided into three grades: 60-120 mesh, 120-200 mesh, and 400-1000 mesh. The proportions of the sandstone dry mixture of the three particle size grades when the packing density is maximum are determined according to the MAA model and the least squares method.

[0010] The feldspar mineral is one or more of albite, potassium feldspar, calcium feldspar, microcline, etc.; the clay mineral is one or more of illite, kaolinite, montmorillonite, chlorite, mica, etc.;

[0011] The solid content of the water glass modulus is 35-40%;

[0012] The nano material is at least one of nano silicon dioxide, nano aluminum oxide, nano glass powder, nano titanium dioxide, etc.;

[0013] The sodium hydroxide is analytically pure, with a purity of ≥96.0%.

[0014] In a second aspect, the present invention provides a method for preparing a sandstone powder-based composite material, the preparation method comprising the following steps:

[0015] 1) Collect natural rock mineral powder, dry it at a temperature of 105±5°C for 120-180min, and perform mineral sorting, discard the part above the 60-mesh sieve and the part below the 1000-mesh sieve, and then separate it into three categories: quartz minerals, feldspar minerals, and clay minerals. The three categories of minerals are mixed according to the mass ratio: quartz minerals 35-50%, feldspar minerals 30-40%, and clay minerals 10-20% to obtain a sandstone dry mixture; the sandstone dry mixture is passed through 120-mesh, 200-mesh, and 400-mesh sieves respectively, and the sandstone dry mixture is divided into three particle size grades of 60-120 mesh, 120-200 mesh, and 400-1000 mesh;

[0016] 2) The particle size distribution of sandstone dry mixture of each particle size grade was tested by laser particle size analyzer; the MAA model was built by Matlab software, and the least square method LSM was used to adjust the mix ratio of 60-120 mesh, 120-200 mesh, and 400-1000 mesh sandstone dry mixture, and the deviation between the synthetic curve function of sandstone dry mixture and the target curve function of MAA model under different mix ratios was calculated, and the residual square sum RSS was minimized to obtain the most densely packed state of theoretical particles; when the distribution modulus q was set to 0.28-0.33, the mix ratios of sandstone dry mixture of three particle size grades with the maximum packing density were obtained;

[0017] 3) Determine the total amount of natural rock minerals according to the sandstone dry mixture ratio determined in step 2), add nanomaterials according to 2-8% of the total amount of natural rock minerals, and mix the nanomaterials into the sandstone dry mixture in multiple times to obtain a uniformly mixed dry powder mixture;

[0018] 4) mixing water glass and sodium hydroxide until they are completely dissolved and uniformly obtained to obtain a modified water glass solution; the addition amounts of the water glass and sodium hydroxide are 16-32% and 0-7.2% of the total amount of natural rock minerals, respectively;

[0019] 5) stirring and mixing the dry powder mixture of step 3) and the modified water glass solution of step 4) to obtain a sandstone-based mixed slurry;

[0020] 6) adding the sandstone-based mixed slurry of step 5) into a steel mold, applying a pressure of 8-17 MPa at room temperature, maintaining the applied pressure for 100-150 seconds after molding, and then releasing the pressure and demolding to obtain a test piece;

[0021] 7) The demoulding specimen is placed in a muffle furnace for high-temperature consolidation, with the starting temperature being room temperature, and the temperature is raised to a target temperature of 350-500°C at a rate of 4-7°C / min, and then kept at the target temperature for 45min-80min and then cooled to room temperature with the furnace to obtain a sandstone-based composite material.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The sandstone powder-based composite material of the present invention uses waste natural rock mineral powder as the only inorganic raw material, and uses gradation design, compaction and high-temperature bonding to achieve low-cost and high-strength material preparation. It provides a feasible idea for the comprehensive utilization of waste rock mineral powder and the development of inorganic building materials.

[0024] 2. In the present invention, 100 parts of natural rock minerals composed of quartz accounting for 35-50% by mass, feldspar minerals accounting for 30-40% by mass, and clay minerals accounting for 10-20% by mass are selected as raw materials. The chemical composition of quartz and feldspar minerals is mainly silicon dioxide. The product after bonding and condensation with water glass has high bonding performance, and the mineral hardness is high. It can provide a certain mechanical strength as "aggregate" after thermal consolidation; in addition, quartz and feldspar minerals have good thermal stability, and will not decompose during high temperature treatment to form defects that reduce the strength of the sample, thereby ensuring its stability at high temperature. At the same time, clay minerals account for 10-20%, which is conducive to the condensation of water glass, and the clay mineral lattice substitution and the negatively charged clay particle plate surface form hydrated Ca 2+ , Na + The adsorption layer is formed on the periphery by hydrated Ca 2+ , Na + It is easy to undergo electrostatic adsorption with silicate ions in water glass to form hydrated calcium silicate gel and form aggregates. The aggregates with large surface energy further lose water and condense to form a network structure product in which crystalline clay minerals and amorphous silicate gel coexist, which improves the cementation properties and thus enhances the mechanical properties.

[0025] 3. The particle size distribution of the sandstone powder in the present invention is designed based on the close packing theory, and the maximum packing density of the sandstone powder is achieved through the MAA model, the porosity between particles is reduced, and a more compact bonding structure is achieved, thereby improving the compressive performance of the sandstone-based composite material. In addition, the maximum particle size of the natural rock mineral powder is controlled to be 60 mesh or less, which not only ensures the mechanical support effect of the "aggregate" of a certain coarse particle, but also avoids the problem of poor bonding performance of the binder due to excessively large particle size.

[0026] 4. The present invention uses water glass as a binder component, and the modulus of water glass is 3.0-3.3. It can form a high bonding structure with clay minerals in rock powder, and can also form silica gel through dehydration condensation under elevated temperature conditions to play a role in bonding rock mineral powder. No additional water is required during the preparation of the system. Nanomaterials are used as reinforcing materials, and their size effect is used to further fill pores, thereby enhancing compactness and compressive strength.

[0027] 5. Under the high temperature curing condition of 350-500℃, the high modulus water glass forms silica gel through dehydration condensation to cement the sandstone powder particles to form good strength. Under the lower compaction pressure (8-17Mpa), by optimizing the compaction density (reaching 18kN / m 3 and above) to achieve higher compressive performance.

[0028] In summary, the sandstone-based composite material and its preparation method proposed in the present invention can prepare inorganic materials of 30 MPa and above at a relatively low consolidation temperature and molding pressure, providing a better idea and research and development basis for the effective utilization of waste stone powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the grading curve optimized using the MAA model particle close packing theory in Example 1.

[0030] Figure 2 Schematic diagram of the grading curve optimized using the MAA model particle close packing theory in Comparative Example 5.

[0031] Figure 3 This is a photo of the rock powder-based composite material prepared in Example 2.

[0032] Figure 4 Microstructure of rock powder-based composite materials. (a) Microstructure of the sample prepared in Comparative Example 3; (b) Microstructure of the sample prepared in Example 2.

[0033] Figure 5 The pore size distribution of the rock powder-based composite material prepared in Example 2. DETAILED DESCRIPTION

[0034] The present invention is further explained below in conjunction with the embodiments and drawings, but this is not intended to limit the scope of protection of the present application.

[0035] The sandstone powder-based composite material of the present invention comprises the following raw materials by weight: 100 parts of natural rock minerals, 16-32 parts of water glass, 2-8 parts of nanomaterials, and 0-6.23 parts of sodium hydroxide;

[0036] Among them, the mass fraction of quartz minerals in natural rock minerals is 35-50%, the mass fraction of feldspar minerals is 30-40%, and the mass fraction of clay minerals is 10-20%;

[0037] The mesh number of the natural rock mineral is 60-1000 meshes; the modulus of the water glass is 3.0-3.3.

[0038] Preferably, the particle sizes of the natural rock minerals are divided into three grades: 60-120 mesh, 120-200 mesh, and 400-1000 mesh, and the proportions of the sandstone dry mixture of the three particle size grades when the packing density is maximum are determined according to the MAA model and the least squares method.

[0039] Preferably, the feldspar mineral is one or more of albite, potassium feldspar, calcium feldspar, and microcline; the clay mineral is one or more of illite, kaolinite, montmorillonite, chlorite, and mica;

[0040] The solid content of the water glass modulus is 35-40%;

[0041] The nano material is at least one of nano silicon dioxide, nano aluminum oxide, nano glass powder, and nano titanium dioxide;

[0042] The sodium hydroxide is analytically pure, with a purity of ≥96.0%.

[0043] The present invention also provides a method for preparing a sandstone powder-based composite material, the preparation method comprising the following steps:

[0044] 1) Collect natural rock mineral powder, dry it at a temperature of 105±5°C for 120-180min, and perform mineral sorting, discard the part above the 60-mesh sieve and the part below the 1000-mesh sieve, and then separate it into three categories: quartz minerals, feldspar minerals, and clay minerals. The three categories of minerals are mixed according to the mass ratio: quartz minerals 35-50%, feldspar minerals 30-40%, and clay minerals 10-20% to obtain a sandstone dry mixture; the sandstone dry mixture is passed through 120-mesh, 200-mesh, and 400-mesh sieves respectively, and the sandstone dry mixture is divided into three particle size grades of 60-120 mesh, 120-200 mesh, and 400-1000 mesh;

[0045] 2) The particle size distribution of sandstone dry mixture of each particle size grade was tested by laser particle size analyzer; the MAA model was built by Matlab software, and the least square method LSM was used to adjust the mix ratio of 60-120 mesh, 120-200 mesh, and 400-1000 mesh sandstone dry mixture, and the deviation between the synthetic curve function of sandstone dry mixture and the target curve function of MAA model under different mix ratios was calculated, and the residual square sum RSS was minimized to obtain the most densely packed state of theoretical particles; when the distribution modulus q was set to 0.28-0.33, the mix ratios of sandstone dry mixture of three particle size grades with the maximum packing density were obtained;

[0046] The formula for the MAA model is:

[0047]

[0048] Where, P is the content of particles, %; D i is the particle size, μm; D min is the minimum particle size, μm; D max is the maximum particle size, μm; q is the distribution modulus.

[0049] 3) Determine the total amount of natural rock minerals according to the sandstone dry mixture ratio determined in step 2), add nanomaterials according to 2-8% of the total amount of natural rock minerals, and mix the nanomaterials into the sandstone dry mixture in multiple times to obtain a uniformly mixed dry powder mixture;

[0050] 4) mixing water glass and sodium hydroxide until they are completely dissolved and uniformly obtained to obtain a modified water glass solution; the addition amounts of the water glass and sodium hydroxide are 16-32% and 0-7.2% of the total amount of natural rock minerals, respectively;

[0051] 5) stirring and mixing the dry powder mixture of step 3) and the modified water glass solution of step 4) to obtain a sandstone-based mixed slurry;

[0052] 6) adding the sandstone-based mixed slurry of step 5) into a steel mold, applying a pressure of 8-17 MPa at room temperature, maintaining the applied pressure for 100-150 seconds after molding, and then releasing the pressure and demolding to obtain a test piece;

[0053] 7) The demoulding specimen is placed in a muffle furnace for high-temperature consolidation, with the starting temperature being room temperature, and the temperature is raised to a target temperature of 350-500°C at a rate of 4-7°C / min, and then kept at the target temperature for 45min-80min and then cooled to room temperature with the furnace to obtain a sandstone-based composite material.

[0054] Further, in step 5), mechanical stirring is performed at a rotation speed of 300-450 r / min for 10-15 min to obtain a sandstone-based mixed slurry.

[0055] The modulus of the modified water glass solution is not less than 2.5.

[0056] Furthermore, the strength of the sandstone-based composite material obtained by the preparation method is not less than 30 MPa, preferably above 35 MPa, 35-50 MPa.

[0057] Example 1

[0058] The sandstone powder-based composite material of this embodiment is

[0059] 1) Dry the natural rock mineral powder at 105° C. for 180 min, and sieve through 60-120 mesh, 120-200 mesh, and 400-1000 mesh sieves, respectively. The composition of the natural rock mineral powder is quartz with a mass fraction of 47%, albite with a mass fraction of 38%, illite with a mass fraction of 8%, and kaolinite with a mass fraction of 7%.

[0060] 2) Use a laser particle size analyzer to test the particle size distribution of each mesh range. According to the modified Andreasen and Andersen particle packing model (MAA model, as shown in Formula 1), the MAA model was built using Matlab software, and the least squares method (LSM) was used to adjust the mix ratios of 60-120 mesh, 120-200 mesh, and 400-1000 mesh natural rock minerals. The deviation between the mixture synthesis curve function and the target curve function of the MAA model under different mix ratios was calculated, and the residual sum of squares (RSS) was minimized to obtain the most densely packed state of theoretical particles. The distribution modulus q was taken as 0.31, and the sandstone dry mixture ratios of three particle size grades at the maximum packing density were obtained, of which 60-120 mesh accounted for 49.3%, 120-200 mesh accounted for 10.3%, and 400-1000 mesh accounted for 40.4%.

[0061] 3) 2 parts of nano-silicon dioxide were mixed into 100 parts of the sandstone dry mix with the above mix ratio in three times to obtain a uniformly mixed dry powder mixture.

[0062] 4) 25 parts of water glass with a modulus of 3.3 and a solid content of 35% are mixed with 4.08 parts of sodium hydroxide until they are completely dissolved and uniformly obtained to obtain a modified water glass solution.

[0063] 5) The dry powder mixture is mixed with the modified water glass solution, and mechanically stirred at a speed of 300 r / min for 15 min until the mixture is uniform, to obtain a sandstone-based mixed slurry.

[0064] 6) The sandstone-based mixed slurry prepared above was added to a 40*40*40mm steel mold, and a pressure of 8.75MPa was applied using a four-column hydraulic press at room temperature. After molding, the applied pressure was maintained for 120s, and then the pressure was released and demolded to obtain a cubic specimen.

[0065] 7) The cube specimen obtained by demolding is placed in a muffle furnace for high-temperature consolidation. The starting temperature is room temperature, and the temperature is increased to a target temperature of 400°C at a rate of 5°C / min. After being kept at the target temperature for 1 hour, it is cooled to room temperature with the furnace to obtain a sandstone-based composite material.

[0066] Example 2

[0067] The difference between this embodiment and embodiment 1 is that no sodium hydroxide is added, 25 parts of water glass are added to the dry powder mixture, and the rest are the same as in embodiment 1.

[0068] Example 3

[0069] The difference between this embodiment and embodiment 1 is that 4 parts of nano silicon dioxide are mixed into the sandstone dry mix three times to obtain a uniformly mixed dry powder mixture. No sodium hydroxide is added, 30 parts of water glass are added to the dry powder mixture, and the rest are the same as in embodiment 1.

[0070] Example 4

[0071] The difference between this embodiment and embodiment 1 is that 25 parts of water glass and 2.42 parts of sodium hydroxide are mixed until they are completely dissolved and uniformly obtained to obtain a modified water glass solution. The rest is the same as in embodiment 1.

[0072] Example 5

[0073] The difference between this embodiment and embodiment 1 is that the cubic specimen obtained by demolding is placed in a muffle furnace for high-temperature consolidation, the initial temperature is room temperature, and the temperature is increased to a target temperature of 450°C at a rate of 5°C / min. After being kept at the target temperature for 1 hour, it is cooled to room temperature with the furnace to obtain a sandstone-based composite material. The rest is consistent with embodiment 1.

[0074] Example 6

[0075] The difference between this embodiment and embodiment 1 is that quartz accounts for 51.9% by mass, plagioclase accounts for 30% by mass, illite accounts for 9.9% by mass, and kaolinite accounts for 8.2% by mass in the natural rock minerals. The natural rock mineral powders are sieved through 60-120 mesh, 120-200 mesh, and 400-1000 mesh sieves respectively, and the rest are the same as in embodiment 1.

[0076] Example 7

[0077] The difference between this embodiment and embodiment 1 is that the prepared sandstone-based mixed slurry is added into a 40*40*40mm steel mold, a pressure of 13.11Mpa is applied by a four-column hydraulic press at room temperature, the applied pressure is maintained for 120s after molding, and then the pressure is released and the mold is demolded to obtain a cubic specimen. The rest is consistent with embodiment 1.

[0078] Comparative Example 1

[0079] The difference between this embodiment and embodiment 1 is that the MAA model is not used to optimize the gradation of natural rock mineral powder, and 100 parts of natural rock minerals are taken, the mesh size is 60-120 mesh, wherein quartz accounts for 47% of the mass fraction, albite accounts for 38% of the mass fraction, illite accounts for 8% of the mass fraction, and kaolinite accounts for 7% of the mass fraction. The rest are the same as in embodiment 1.

[0080] Comparative Example 2

[0081] The difference between this embodiment and embodiment 1 is that the prepared sandstone-based mixed slurry is added into a 40*40*40mm steel mold, a pressure of 25Mpa is applied by a four-column hydraulic press at room temperature, the applied pressure is maintained for 120s after molding, and then the pressure is released and the mold is demolded to obtain a cubic specimen. The rest is consistent with embodiment 1.

[0082] Comparative Example 3

[0083] The difference between this embodiment and embodiment 1 is that no sodium hydroxide is added, 38 parts of water glass are added to the dry powder mixture, and the rest are the same as in embodiment 1.

[0084] Comparative Example 4

[0085] The difference between this embodiment and embodiment 1 is that the cubic specimen obtained by demolding is placed in a muffle furnace for high-temperature consolidation, the starting temperature is room temperature, and the temperature is increased to a target temperature of 600°C at a rate of 5°C / min. After being kept at the target temperature for 1 hour, it is cooled to room temperature with the furnace to obtain a sandstone-based composite material. The rest is consistent with embodiment 1.

[0086] Comparative Example 5

[0087] The difference between this embodiment and embodiment 1 is that quartz accounts for 47% of the mass fraction, albite accounts for 38% of the mass fraction, illite accounts for 8% of the mass fraction, and kaolinite accounts for 7% of the mass fraction in the natural rock minerals. It is divided into three grades: 30-60 mesh, 120-200 mesh, and 400-1000 mesh.

[0088] The particle size distribution of each mesh range was tested using a laser particle size analyzer. According to the modified Andreasen and Andersen particle packing model (MAA model) (such as formula 1), the MAA model was modeled using Matlab software, and the least square method (LSM) was used to adjust the mix ratio of 30-60 mesh, 120-200 mesh, and 400-1000 mesh natural rock minerals. The deviation between the mixture synthesis curve function and the target curve function of the MAA model under different mix ratios was calculated, and the residual sum of squares (RSS) was minimized to obtain the most densely packed state of theoretical particles. Its distribution modulus q was taken as 0.31, and finally the sandstone dry mixture ratio with the largest packing density was obtained, of which 30-60 mesh accounted for 47.5%, 120-200 mesh accounted for 21.1%, and 400-1000 mesh accounted for 31.4%.

[0089] The rest are the same as in Example 1.

[0090] Compressive strength(MPa) Example 1 37.36 Example 2 39.77 Example 3 41.3 Example 4 39.14 Example 5 38.65 Example 6 40.48 Example 7 44.38 Comparative Example 1 12.88 Comparative Example 2 21.41 Comparative Example 3 20.2 Comparative Example 4 24.44 Comparative Example 5 22.53

[0091] Any matters not described in the present invention are applicable to the prior art.

Claims

1. A sandstone powder-based composite material, characterized in that: The raw materials of the composite material are calculated by weight: 100 parts of natural rock minerals, 16-32 parts of water glass, 2-8 parts of nanomaterials, and 0-6.23 parts of sodium hydroxide; Among them, the mass fraction of quartz minerals in natural rock minerals is 35-50%, the mass fraction of feldspar minerals is 30-40%, and the mass fraction of clay minerals is 10-20%; The mesh number of the natural rock mineral is 60-1000 meshes; the modulus of the water glass is 3.0-3.

3.

2. The sandstone powder-based composite material according to claim 1, characterized in that: The particle sizes of the natural rock minerals are divided into three grades: 60-120 mesh, 120-200 mesh, and 400-1000 mesh. The proportions of the sandstone dry mixture of the three particle size grades when the packing density is maximum are determined according to the MAA model and the least squares method.

3. The sandstone powder-based composite material according to claim 1, characterized in that: The feldspar mineral is one or more of albite, potassium feldspar, calcium feldspar, and microcline; the clay mineral is one or more of illite, kaolinite, montmorillonite, chlorite, and mica; The solid content of the water glass modulus is 35-40%; The nano material is at least one of nano silicon dioxide, nano aluminum oxide, nano glass powder, and nano titanium dioxide; The sodium hydroxide is analytically pure, with a purity of ≥96.0%.

4. A method for preparing a sandstone powder-based composite material, characterized in that: The preparation method comprises the following steps: 1) Collect natural rock mineral powder, dry it at a temperature of 105±5°C for 120-180min, and perform mineral sorting, discard the part above the 60-mesh sieve and the part below the 1000-mesh sieve, and then separate it into three categories: quartz minerals, feldspar minerals, and clay minerals. The three categories of minerals are mixed according to the mass ratio: quartz minerals 35-50%, feldspar minerals 30-40%, and clay minerals 10-20% to obtain a sandstone dry mixture; the sandstone dry mixture is passed through 120-mesh, 200-mesh, and 400-mesh sieves respectively, and the sandstone dry mixture is divided into three particle size grades of 60-120 mesh, 120-200 mesh, and 400-1000 mesh; 2) The particle size distribution of sandstone dry mixture of each particle size grade was tested by laser particle size analyzer; the MAA model was built by Matlab software, and the least square method LSM was used to adjust the mix ratio of 60-120 mesh, 120-200 mesh, and 400-1000 mesh sandstone dry mixture, and the deviation between the synthetic curve function of sandstone dry mixture and the target curve function of MAA model under different mix ratios was calculated, and the residual square sum RSS was minimized to obtain the most densely packed state of theoretical particles; when the distribution modulus q was set to 0.28-0.33, the mix ratios of sandstone dry mixture of three particle size grades with the maximum packing density were obtained; 3) Determine the total amount of natural rock minerals according to the sandstone dry mixture ratio determined in step 2), add nanomaterials according to 2-8% of the total amount of natural rock minerals, and mix the nanomaterials into the sandstone dry mixture in multiple times to obtain a uniformly mixed dry powder mixture; 4) mixing water glass and sodium hydroxide until they are completely dissolved and uniformly obtained to obtain a modified water glass solution; the addition amounts of the water glass and sodium hydroxide are 16-32% and 0-7.2% of the total amount of natural rock minerals, respectively; 5) stirring and mixing the dry powder mixture of step 3) and the modified water glass solution of step 4) to obtain a sandstone-based mixed slurry; 6) adding the sandstone-based mixed slurry of step 5) into a steel mold, applying a pressure of 8-17 MPa at room temperature, maintaining the applied pressure for 100-150 seconds after molding, and then releasing the pressure and demolding to obtain a test piece; 7) The demoulding specimen is placed in a muffle furnace for high-temperature consolidation, with the starting temperature being room temperature, and the temperature is raised to a target temperature of 350-500°C at a rate of 4-7°C / min, and then kept at the target temperature for 45min-80min and then cooled to room temperature with the furnace to obtain a sandstone-based composite material.

5. The preparation method according to claim 4, characterized in that: In step 5), the mixture is mechanically stirred at a rotation speed of 300-450 r / min for 10-15 min to obtain a sandstone-based mixed slurry.

6. The preparation method according to claim 4, characterized in that: The strength of the sandstone-based composite material obtained by the preparation method is not less than 30 MPa.

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