High-strength high-temperature-resistant cementing material and preparation method thereof

Abstract

The invention relates to a high-strength high-temperature-resistant cementing material and a preparation method thereof, belongs to the technical field of cementing materials, and solves the problems of complex preparation process, low strength, easiness in bleeding and segregation, poor high temperature resistance and the like of the traditional cementing material. The preparation method comprises the following steps: stirring silica sol to uniformly disperse the silica sol; adding a silane coupling agent into the silica sol, and stirring until the materials are uniformly mixed to obtain a first mixed solution; adding the first enhanced raw material powder into the first mixed solution, and stirring until the first enhanced raw material powder is uniformly dispersed to obtain a second mixed solution; adding the second enhanced raw material powder into the second mixed solution, and stirring until the second enhanced raw material powder is uniformly dispersed to obtain a third mixed solution; adding a gel accelerator into the third mixed solution, and stirring to obtain sol; after the sol is molded, standing and aging are conducted, and gel is obtained; and drying the gel in a drying oven to obtain the high-strength high-temperature-resistant cementing material. The high-strength high-temperature-resistant cementing material prepared by the method disclosed by the invention is good in integrity, excellent in mechanical property and good in high temperature resistance and freezing resistance.

Description

Technical Field

[0001] This invention relates to the field of cementitious materials technology, and in particular to a high-strength, high-temperature resistant cementitious material and its preparation method. Background Technology

[0002] Cementitious materials are materials that, through physical and chemical processes, transform from a plastic paste into a hard, stone-like substance, binding granular or blocky materials into a whole and giving it a certain strength.

[0003] Traditional cementitious materials, such as silicate cement, are an indispensable part of construction engineering. They enhance the strength and durability of building materials, and also provide reinforcement, bonding, pore filling, and repair. However, their production process consumes large amounts of non-renewable resources, such as limestone and clay, while simultaneously emitting significant amounts of waste gas and dust, resulting in substantial waste of resources and energy and significant environmental pollution. Furthermore, traditional cementitious materials suffer from drawbacks such as low strength, susceptibility to bleeding and segregation, and poor high-temperature and frost resistance. Therefore, there is an urgent need in the construction and other fields to develop a new type of low-carbon, low-energy cementitious material.

[0004] To find suitable alternatives to cementitious materials, alkali-activated cementitious materials have attracted attention and been studied. Alkali-activated cementitious materials refer to raw materials made by reacting materials with pozzolanic activity or potential hydraulic properties with activators. Their production does not require calcination, significantly reducing energy consumption and CO2 emissions. Furthermore, due to their good mechanical properties, they are widely used in construction, roads, bridges, and water conservancy. However, with the continuous development of alkali-activated cementitious materials, many problems still exist. First, the source of raw materials for alkali-activated cementitious materials is difficult to control and fluctuates greatly; second, the strength formation principle of alkali-activated cementitious materials differs from that of traditional cementitious materials, and their mix design still needs further research; moreover, alkali-activated cementitious materials suffer from serious problems such as the release of alkaline substances with water vapor and the reaction of alkaline substances with CO2 in the air, which significantly affect their performance and limit their application. Therefore, considering the development and application problems of traditional cementitious materials and alkali-activated cementitious materials, it is particularly important to research a new type of cementitious material with a simple and safe preparation method, stable raw material source, energy saving and environmental protection, and excellent structural performance. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a high-strength high-temperature resistant cementitious material and its preparation method to solve one of the following technical problems: (1) The preparation process of traditional cementitious materials is complicated, the strength is low, it is easy to bleed and separate, and the energy consumption is high; (2) Traditional cementitious materials have poor high temperature resistance and freeze resistance; (3) The preparation of traditional cementitious materials will cause environmental pollution; (4) The source of raw materials for alkali-activated cementitious materials is unstable and fluctuates greatly; (5) Alkali-activated cementitious materials also have problems such as alkaline substances in the material being released with water vapor and alkaline substances reacting with CO2 in the air.

[0006] The objective of this invention is mainly achieved through the following technical solutions:

[0007] On one hand, the present invention provides a method for preparing a high-strength, high-temperature resistant cementitious material, comprising:

[0008] Step 1: Stir the silica sol to disperse it evenly;

[0009] Step 2: Add the silane coupling agent to the silica sol and stir thoroughly until the mixture is homogeneous to obtain the first mixture.

[0010] Step 3: Add the first reinforcing raw material powder to the first mixture and stir thoroughly until it is evenly dispersed to obtain the second mixture;

[0011] Step 4: Add the second reinforcing raw material powder to the second mixture and stir thoroughly until it is evenly dispersed to obtain the third mixture;

[0012] Step 5: Add the gelation accelerator to the third mixture and stir thoroughly to obtain a sol;

[0013] Step 6: After shaping the sol, let it stand and age to obtain a smooth gel.

[0014] Step 7: Place the gel in an oven to dry, and obtain a high-strength, high-temperature resistant gelling material.

[0015] Furthermore, in step 1, the silica sol is an alkaline silica sol.

[0016] Furthermore, in step 2, the mass of the silane coupling agent is 1% to 3% of the mass of the silica sol.

[0017] Furthermore, in step 3, the first reinforcing raw material powder is made of a high-strength and water-resistant material.

[0018] Furthermore, in step 3, the first reinforcing raw material powder includes one or more of calcium carbonate, calcium hydroxide, barium sulfate, and barium carbonate.

[0019] Furthermore, in step 4, the second reinforcing raw material powder includes one or more of aluminum hydroxide, kaolin, acidified dry adhesive powder, and nano-alumina.

[0020] Furthermore, in step 5, the gelation accelerator is calcium sulfate; the mass of the gelation accelerator is 7% to 10% of the mass of the silica sol.

[0021] Furthermore, in steps 3, 4, and 5, the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder, and the gelation accelerator is (22-54):(15-63):100.

[0022] Furthermore, in step 6, the temperature for static aging is 20–30°C, and the time is 12–24 hours.

[0023] The present invention also provides a high-strength, high-temperature resistant cementitious material, which is prepared by the above-described preparation method.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] (1) In the preparation method of the high-strength, high-temperature resistant cementitious material of the present invention, silica sol is used as raw material. By adding silane coupling agent to it, and by sequentially adding first reinforcing raw material powder, second reinforcing raw material powder and gelation accelerator, after aging and drying, a cementitious material with excellent mechanical properties and high temperature resistance is obtained. Among them, when the silane coupling agent is added to the alkaline silica sol, it can crosslink with the gel structure in the alkaline silica sol, which can improve the stability of the gel structure, reduce particle agglomeration, and increase the compressive strength and durability of the cementitious material. The first reinforcing raw material powder and the second reinforcing raw material powder are fillers in the cementitious material. Due to their own properties, they can provide the cementitious material with certain high temperature resistance and water resistance. They work together with the alkaline silica sol and the silane coupling agent to form a strong gel network structure, which improves the strength of the cementitious material and improves its overall performance. Finally, the addition of the gelation accelerator can not only be used to adjust the curing speed of the cementitious material to make the experiment controllable, but also provide the cementitious material with certain strength, water resistance and other properties.

[0026] (2) In the preparation method of the present invention, during the static aging and drying process, the temperature and time are precisely controlled to avoid large cracking of the gelling material, and finally a gelling material with good integrity and durability is obtained.

[0027] (3) The preparation method of the present invention is green and environmentally friendly, does not require sintering, has low energy consumption, simple process, wide and stable source of raw materials, low equipment cost, high output, and can improve production efficiency; the shape of the prepared material is not limited to regular shape, and can also be made into complex and irregular gelling materials; and the preparation method is highly safe, hardly causes environmental pollution, and is highly operable and applicable.

[0028] (4) The high-strength, high-temperature resistant cementitious material of the present invention has good integrity, excellent mechanical properties, is not prone to bleeding and segregation, and has good high-temperature resistance and freeze-thaw resistance; for example, the porosity of the cementitious material is between 7.9% and 12.4% (e.g., 8.1% to 12.4%), the water absorption rate is 4.8% to 9.1% (e.g., 5.0% to 9.1%), and the density is 1.6 to 2.1 g / cm³. 3 (e.g., 1.6–2.0 g / cm³) 3 The hardness is 19.9–28 HV (e.g., 19.9–27.9 HV), and the compressive strength is 63.7–78 MPa (e.g., 63.7–77.3 MPa). After the cementitious material is calcined at 1000℃, the product remains intact, with a compressive strength of 47.9–55 MPa. After soaking in water for 15 days, the compressive strength is 58.1–70 MPa. After soaking in water for 1 day and then freezing at -18℃ for 15 days, the compressive strength is 54.9–63 MPa.

[0029] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments described and the accompanying drawings. Attached Figure Description

[0030] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] Figure 1 An optical image of the cementitious material of Embodiment 1 of the present invention;

[0032] Figure 2 An optical image of the cementitious material of Comparative Example 1 of the present invention;

[0033] Figure 3 This is a SEM image of the cementitious material of Example 2 of the present invention;

[0034] Figure 4 This is a SEM image of the cementitious material of Comparative Example 2 of the present invention;

[0035] Figure 5An optical image of the cementitious material of Comparative Example 3 of the present invention;

[0036] Figure 6 This is an optical image of the cementitious material of Example 4 of the present invention. Detailed Implementation

[0037] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0038] This invention provides a method for preparing a high-strength, high-temperature resistant cementitious material, comprising:

[0039] Step 1: Stir the silica sol to disperse it evenly;

[0040] Step 2: Add the silane coupling agent to the silica sol and stir thoroughly until the mixture is uniform, resulting in a first mixed liquid that is translucent and covered with oil droplets.

[0041] Step 3: Add the first reinforcing raw material powder to the first mixture and stir thoroughly until it is evenly dispersed to obtain a light-colored second mixture;

[0042] Step 4: Add the second reinforcing raw material powder to the second mixture and stir thoroughly until it is evenly dispersed to obtain a white third mixture;

[0043] Step 5: Add the gelation accelerator to the third mixture and stir thoroughly to obtain a white, reflective, and thick sol.

[0044] Step 6: After shaping the sol, let it stand at room temperature to age and obtain a smooth gel.

[0045] Step 7: Place the gel in an oven without forced air to dry, and obtain a gel material with good integrity, high strength and high hardness.

[0046] Specifically, in step 1 above, the silica sol used is alkaline silica sol. This is because: (1) Alkaline silica sol has better impermeability and chemical corrosion resistance, can fill micropores and microcracks, reduce shrinkage and cracking of cementitious materials, and help improve the overall performance and durability of cementitious materials; (2) Alkaline silica sol has better gelation reaction performance than neutral or acidic silica sol, and it has faster early strength development in cementitious materials and stronger adhesion, thus improving the strength and durability of cementitious materials; (3) Alkaline silica sol has high stability and can maintain its dispersed state within a certain temperature and pH range, and is not prone to gelation and precipitation, which can ensure that the sol is fully mixed with other components; (4) Alkaline silica sol has high alkalinity, which can provide sufficient alkaline conditions to promote the reaction.

[0047] Specifically, in steps 1 to 5 above, considering that using magnetic stirring would cause the raw materials to adhere to the magnetic stir bar, resulting in uneven dispersion of the system, this would not only reduce the uniformity of the internal structure of the product and generate a large number of defects, but also waste raw materials. Therefore, manual stirring was used for all steps.

[0048] Specifically, when manually stirring, try to maintain a constant stirring speed. When stirring at a constant speed, stir in a circular motion from the center of the cup towards the edge, and then stir in a circular motion from the edge towards the center. This will ensure that the medicine is evenly dispersed in the system. Also, when stirring at a constant speed, the force should be applied to the end of the glass rod that is against the bottom of the cup, rather than by tossing the rod.

[0049] Specifically, in step 1 above, considering that the silica sol may become uneven in density due to prolonged storage, which would reduce the integrity of the product and decrease its mechanical properties, the stirring time is 2–4 minutes.

[0050] Specifically, in step 2 above, the silane coupling agent is one or more of KH-560 and KH-570;

[0051] Specifically, in step 2 above, excessive amounts of silane coupling agent would accelerate gelation, hindering the shaping of the sol obtained in step 5 and causing excessive particle agglomeration within the product, reducing structural uniformity, lowering product integrity and strength, and increasing production costs. Conversely, insufficient amounts of silane coupling agent would have minimal effect on improving product performance, failing to achieve the modification objective. Therefore, the mass of the silane coupling agent should be controlled to be 1%–3% of the mass of the silica sol.

[0052] Specifically, in step 3 above, considering that the cementitious material needs to have high strength, high hardness, and good water resistance, the first reinforcing raw material powder is made of a high-strength and water-resistant material. For example, the first reinforcing raw material powder includes one or more of calcium carbonate, calcium hydroxide, barium sulfate, and barium carbonate.

[0053] Considering that cementitious materials need to possess good mechanical properties, good water resistance, and high-temperature resistance, the second reinforcing raw material powder is selected from powders that can improve mechanical properties, provide water resistance, and enable the product to withstand high temperatures. For example, the second reinforcing raw material powder includes one or more of aluminum hydroxide, kaolin, acidified dry adhesive powder (dry adhesive powder treated with 0.3 mol / L nitric acid), and nano-alumina.

[0054] Specifically, the particle size of the first reinforcing raw material powder is larger than that of the second reinforcing raw material powder.

[0055] It should be noted that, through in-depth research, the inventors discovered that the order in which the first and second reinforcing raw material powders are added in steps 3 and 4 above needs to be strictly controlled. The advantages of adding the first reinforcing raw material powder first, followed by the second, are as follows: the particle size of the first reinforcing raw material powder is larger than that of the second. Adding the first first and then the second can maximize the filling of micropores and defects in the cementitious material, enhancing its density and strength, and improving its overall performance. Adding the first reinforcing raw material powder first provides greater skeletal strength to the sol-gel network, giving the cementitious material relatively good mechanical properties. Adding the second reinforcing raw material powder then provides additional reinforcement. The combination of the two forms a robust gel network structure, improving overall performance. Following this order can maximize the overall performance of the cementitious material and avoid some possible adverse reactions that could lead to a decrease in the material's performance.

[0056] The inventors discovered in their research that the first reinforcing raw material powder and the second reinforcing raw material powder cannot be added at the same time. This is because: firstly, the simultaneous addition of the first reinforcing raw material powder and the second reinforcing raw material powder results in a competitive relationship, making the reaction difficult to control and regulate, which will affect the reaction rate and performance of the cementitious material; secondly, simultaneous addition easily leads to mixing difficulties, making it difficult to achieve uniform dispersion, which will affect the performance and stability of the material.

[0057] The inventors discovered in their research that the order in which the first reinforcing raw material powder and the second reinforcing raw material powder are added cannot be changed. The first reinforcing raw material powder and the second reinforcing raw material powder have different particle size distributions and physical properties. Changing the order will lead to poor filling of the first reinforcing raw material powder and may also lead to uneven mixing, reducing the strength and overall performance of the material.

[0058] Specifically, in steps 2, 3, and 4 above, considering that too short a stirring time would lead to uneven dispersion of the silane coupling agent and reinforcing raw material powder, resulting in particle agglomeration inside the product, cracking after drying, and reduced mechanical properties, while too long a stirring time would prolong the production cycle and reduce production efficiency, the stirring time is controlled to be 3–5 minutes.

[0059] Specifically, in step 5 above, considering that it can provide certain mechanical properties and water resistance to the cementitious material, calcium sulfate is used as the gelation accelerator.

[0060] Specifically, in step 5 above, considering that excessively high quality gel accelerators reduce the system's dispersibility, easily leading to particle agglomeration, resulting in more cracks and fissures after drying, reducing strength, and increasing production costs; while excessively low quality gel accelerators provide limited strength, prolonging gelation time or even preventing gelation altogether, thus affecting production efficiency, the quality of the gel accelerator is controlled to be 7%–10% of the silica sol's mass, for example, 8% or 9%.

[0061] Specifically, in step 5 above, considering that too short a stirring time would result in a high moisture content in the sol system, leading to more cracks in the product during drying and reducing its mechanical properties, while too long a stirring time would increase the viscosity of the sol, making it impossible to mold a smooth and flat product, and would also increase the production cycle and reduce production efficiency, stirring should be stopped and the product immediately shaped when there are almost no air bubbles in the sol system, and the moisture has mostly evaporated, and the liquid moving towards the center changes from spreading rapidly to spreading slowly, indicating that it is about to gel.

[0062] Specifically, the sol in step 5 above is quite viscous and does not flow when tilted at 45°.

[0063] Specifically, in steps 3, 4, and 5 above, considering that if the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder, and the gel accelerator is too high, the concentration of the sol system will be too high, the raw material powder will not be effectively dispersed, and some will agglomerate outside the sol network. During gel drying, this will generate more cracks and fissures, resulting in poor integrity, reduced strength, and increased production costs. If the mass ratio is too low, the density of the product will decrease, and the strength provided by the reinforcing raw material powder will be less, resulting in low product strength. Therefore, the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder, and the gel accelerator should be controlled as (22–54):(15–63):100, for example, (25–50):(25–63):100.

[0064] Specifically, in step 6 above, a longer aging time would lengthen the production cycle and reduce production efficiency; a shorter aging time would prevent the sol components from reacting fully, resulting in incomplete particle polymerization and an inability to form a good network skeleton structure, leading to cracking of the dried product and reduced strength. Under suitable aging conditions, a lower aging temperature would result in insufficient formation of the sol network skeleton, reducing the mechanical properties of the product; a higher aging temperature would decrease sol stability, leading to incomplete particle polymerization and cracking of the dried product, thus reducing its strength. Therefore, the static aging temperature should be controlled at 20–30℃, and the time at 12–24 hours.

[0065] Specifically, in step 7 above, considering that free water inside the product evaporates rapidly under the forced air condition of the oven, many tiny capillaries may form inside the product, resulting in uneven shrinkage. Excessive capillary force can cause the product to crack or deform. Therefore, the oven is controlled to be in a non-forced air condition.

[0066] Specifically, in step 7 above, it is considered that excessively high drying temperatures will generate greater capillary forces, leading to increased shrinkage and potentially causing product cracking; while excessively low drying temperatures will prolong the drying cycle and increase production costs. Under suitable drying temperatures, too short a drying time results in incomplete drying of the product, reducing its strength; too long a drying time allows all internal moisture to evaporate, extending the drying cycle and increasing production costs. Therefore, the drying temperature of the oven is controlled at 40–60℃, and the drying time is 2–4 days.

[0067] The present invention also provides a high-strength, high-temperature resistant cementitious material, which is prepared by the above-described preparation method.

[0068] The high-strength, high-temperature resistant cementitious material of this invention exhibits good integrity, excellent mechanical properties, resistance to bleeding and segregation, and good high-temperature and frost resistance. For example, the porosity of the cementitious material is between 7.9% and 12.4% (e.g., 8.1% to 12.4%), the water absorption rate is 4.8% to 9.1% (e.g., 5.0% to 9.1%), and the density is 1.6 to 2.1 g / cm³. 3 (e.g., 1.6–2.0 g / cm³) 3 The hardness is 19.9–28 HV (e.g., 19.9–27.9 HV), and the compressive strength is 63.7–78 MPa (e.g., 63.7–77.3 MPa). After the cementitious material is calcined at 1000℃, the product remains intact, with a compressive strength of 47.9–55 MPa. After soaking in water for 15 days, the compressive strength is 58.1–70 MPa. After soaking in water for 1 day and then freezing at -18℃ for 15 days, the compressive strength is 54.9–63 MPa.

[0069] The high-strength, high-temperature resistant cementitious material of this invention can be used as an exterior wall material, a fireproof and high-temperature resistant material, and in mining backfilling projects.

[0070] The present invention will now be described in detail with reference to specific embodiments, in which multiple parallel samples were prepared in both the specific embodiments and the comparative examples.

[0071] Example 1

[0072] This embodiment provides a high-strength, high-temperature resistant cementitious material and its preparation method. In this embodiment, silica sol is selected as the matrix, calcium carbonate as the first reinforcing raw material powder, aluminum hydroxide as the second reinforcing raw material powder, silane coupling agent KH-560 as the modifier, and calcium sulfate as the gelation accelerator. The mass of the silane coupling agent is 2% of the mass of the silica sol, the mass of the gelation accelerator is 9% of the mass of the silica sol, and the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder, and the gelation accelerator is 28:35:100.

[0073] The preparation method includes the following steps:

[0074] Step 1: Stir the silica sol for 2 minutes to disperse it evenly;

[0075] Step 2: Add the silane coupling agent to the silica sol and stir for 3 minutes to mix it evenly, thus obtaining the first mixture.

[0076] Step 3: Add the first reinforcing raw material powder to the first mixture and stir for 3 minutes to disperse it evenly, thus obtaining the second mixture;

[0077] Step 4: Add the second reinforcing raw material powder to the second mixture and stir for 3 minutes to disperse it evenly, thus obtaining the third mixture;

[0078] Step 5: Add the gelation accelerator to the third mixture and stir thoroughly to obtain a sol;

[0079] Step 6: After shaping the sol, place it at 25°C and let it stand for 24 hours to obtain a gel;

[0080] Step 7: Place the gel in a 60°C oven without forced air and dry for 3 days to obtain the gel material.

[0081] Figure 1 The image shown is an optical image of the cementitious material in this embodiment. It can be seen that the surface of the cementitious material in this embodiment is flat and smooth, and has good integrity.

[0082] The cementitious material of this embodiment exhibits good integrity, high strength, resistance to bleeding and segregation, good high-temperature resistance and frost resistance, a porosity of 8.1%–8.4%, a water absorption rate of 5.0%–5.5%, and a density of 1.9–2.0 g / cm³. 3 The hardness is 26.2–27.9 HV, the compressive strength is 74.9–77.3 MPa, and after calcination at 1000℃, the product remains intact with a compressive strength of 53.2–54.4 MPa. After soaking in water for 15 days, the compressive strength is 68.2–69.8 MPa. After soaking in water for 1 day and then freezing directly at -18℃ for 15 days, the compressive strength is 61.5–62.7 MPa.

[0083] Example 2

[0084] This embodiment provides a high-strength, high-temperature resistant cementitious material and its preparation method. In this embodiment, silica sol is selected as the matrix, calcium carbonate as the first reinforcing raw material powder, acidified dry adhesive powder as the second reinforcing raw material powder, silane coupling agent KH-570 as the modifier, and calcium sulfate as the gelation accelerator. The mass of the silane coupling agent is 2% of the mass of the silica sol, the mass of the gelation accelerator is 9% of the mass of the silica sol, and the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder and the gelation accelerator is 28:35:100.

[0085] The preparation method includes the following steps:

[0086] Step 1: Stir the silica sol for 2 minutes to disperse it evenly;

[0087] Step 2: Add the silane coupling agent to the silica sol and stir for 3 minutes to mix it evenly, thus obtaining the first mixture.

[0088] Step 3: Add the first reinforcing raw material powder to the first mixture and stir for 3 minutes to disperse it evenly, thus obtaining the second mixture;

[0089] Step 4: Add the second reinforcing raw material powder to the second mixture and stir for 3 minutes to disperse it evenly, thus obtaining the third mixture;

[0090] Step 5: Add the gelation accelerator to the third mixture and stir thoroughly to obtain a sol;

[0091] Step 6: After shaping the sol, place it at 25°C and let it stand for 24 hours to obtain a gel;

[0092] Step 7: Place the gel in a 60°C oven without forced air and dry for 3 days to obtain the gel material.

[0093] Figure 3 The image shown is an SEM image of the cementitious material in this embodiment. It can be seen that the cementitious material in this embodiment has virtually no cracks and good density, so the cementitious material has high strength.

[0094] The cementitious material in this embodiment has a porosity of 10.3%–10.6%, a water absorption rate of 7.2%–7.8%, and a density of 1.7–1.8 g / cm³. 3 It has a hardness of 22.0–23.7 HV, a compressive strength of 67.6–70.1 MPa, and good integrity.

[0095] Example 3

[0096] This embodiment provides a high-strength, high-temperature resistant cementitious material and its preparation method. In this example, silica sol is selected as the matrix, barium carbonate as the first reinforcing raw material powder, nano-alumina as the second reinforcing raw material powder, silane coupling agent KH-560 as the modifier, and calcium sulfate as the gelation promoter. The mass of the silane coupling agent is 2% of the mass of the silica sol, the mass of the gelation promoter is 9% of the mass of the silica sol, and the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder, and the gelation promoter is 28:35:100.

[0097] The preparation method includes the following steps:

[0098] Step 1: Stir the silica sol for 2 minutes to disperse it evenly;

[0099] Step 2: Add the silane coupling agent to the silica sol and stir for 3 minutes to mix it evenly, thus obtaining the first mixture.

[0100] Step 3: Add the first reinforcing raw material powder to the first mixture and stir for 3 minutes to disperse it evenly, thus obtaining the second mixture;

[0101] Step 4: Add the second reinforcing raw material powder to the second mixture and stir for 3 minutes to disperse it evenly, thus obtaining the third mixture;

[0102] Step 5: Add the gelation accelerator to the third mixture and stir thoroughly to obtain a sol;

[0103] Step 6: After shaping the sol, place it at 25°C and let it stand for 24 hours to obtain a gel;

[0104] Step 7: Place the gel in a 60°C oven without forced air and dry for 3 days to obtain the gel material.

[0105] The cementitious material in this embodiment has good integrity, a porosity of 11.4%–11.8%, a water absorption rate of 8.3%–8.9%, and a density of 1.6–1.7 g / cm³. 3 The hardness is 20.1–21.6 HV, the compressive strength is 64.2–66.6 MPa, and after calcination at 1000℃, the product remains intact with a compressive strength of 47.9–49.4 MPa. After soaking in water for 15 days, the compressive strength is 58.1–59.5 MPa. After soaking in water for 1 day and then freezing at -18℃ for 15 days, the compressive strength is 54.9–56.1 MPa.

[0106] Example 4

[0107] This embodiment provides a high-strength, high-temperature resistant cementitious material and its preparation method. In this example, silica sol is selected as the matrix, barium carbonate as the first reinforcing raw material powder, aluminum hydroxide as the second reinforcing raw material powder, silane coupling agent KH-570 as the modifier, and calcium sulfate as the gelation promoter. The mass of the silane coupling agent is 2% of the mass of the silica sol, the mass of the gelation promoter is 9% of the mass of the silica sol, and the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder, and the gelation promoter is 28:35:100.

[0108] The preparation method includes the following steps:

[0109] Step 1: Stir the silica sol for 2 minutes to disperse it evenly;

[0110] Step 2: Add the silane coupling agent to the silica sol and stir for 3 minutes to mix it evenly, thus obtaining the first mixture.

[0111] Step 3: Add the first reinforcing raw material powder to the first mixture and stir for 3 minutes to disperse it evenly, thus obtaining the second mixture;

[0112] Step 4: Add the second reinforcing raw material powder to the second mixture and stir for 3 minutes to disperse it evenly, thus obtaining the third mixture;

[0113] Step 5: Add the gelation accelerator to the third mixture and stir thoroughly to obtain a sol;

[0114] Step 6: After shaping the sol, place it at 25°C and let it stand for 24 hours to obtain a gel;

[0115] Step 7: Place the gel in a 60°C oven without forced air and dry for 3 days to obtain the gel material.

[0116] Figure 6 The image shown is an optical image of the cementitious material in this embodiment. It can be seen that the surface of the cementitious material in this embodiment is smooth and flat, and has good integrity.

[0117] The cementitious material in this embodiment has a porosity of 9.2%–9.4%, a water absorption rate of 6.4%–6.9%, and a density of 1.8–1.9 g / cm³. 3 It has a hardness of 24.2–25.8 HV, a compressive strength of 71.2–73.4 MPa, and good integrity.

[0118] Example 5

[0119] This embodiment provides a high-strength, high-temperature resistant cementitious material and its preparation method. In this embodiment, silica sol is selected as the matrix, calcium carbonate as the first reinforcing raw material powder, acidified dry adhesive powder as the second reinforcing raw material powder, silane coupling agent KH-570 as the modifier, and calcium sulfate as the gelation accelerator. The mass of the silane coupling agent is 2% of the mass of the silica sol, the mass of the gelation accelerator is 9% of the mass of the silica sol, and the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder and the gelation accelerator is 33:26:100.

[0120] The preparation method includes the following steps:

[0121] Step 1: Stir the silica sol for 2 minutes to disperse it evenly;

[0122] Step 2: Add the silane coupling agent to the silica sol and stir for 3 minutes to mix it evenly, thus obtaining the first mixture.

[0123] Step 3: Add the first reinforcing raw material powder to the first mixture and stir for 3 minutes to disperse it evenly, thus obtaining the second mixture;

[0124] Step 4: Add the second reinforcing raw material powder to the second mixture and stir for 3 minutes to disperse it evenly, thus obtaining the third mixture;

[0125] Step 5: Add the gelation accelerator to the third mixture and stir thoroughly to obtain a sol;

[0126] Step 6: After shaping the sol, place it at 25°C and let it stand for 24 hours to obtain a gel;

[0127] Step 7: Place the gel in a 60°C oven without forced air and dry for 3 days to obtain the gel material.

[0128] The cementitious material in this embodiment has a porosity of 11.7%–12.4%, a water absorption rate of 8.6%–9.1%, and a density of 1.6–1.7 g / cm³. 3 It has a hardness of 19.9–20.8 HV, a compressive strength of 63.7–64.9 MPa, and good integrity.

[0129] Example 6

[0130] This embodiment provides a high-strength, high-temperature resistant cementitious material and its preparation method. In this embodiment, silica sol is selected as the matrix, calcium carbonate as the first reinforcing raw material powder, aluminum hydroxide as the second reinforcing raw material powder, silane coupling agent KH-560 as the modifier, and calcium sulfate as the gelation promoter. The mass of the silane coupling agent is 2% of the mass of the silica sol, the mass of the gelation promoter is 9% of the mass of the silica sol, and the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder, and the gelation promoter is 49:61:100.

[0131] The preparation method includes the following steps:

[0132] Step 1: Stir the silica sol for 2 minutes to disperse it evenly;

[0133] Step 2: Add the silane coupling agent to the silica sol and stir for 3 minutes to mix it evenly, thus obtaining the first mixture.

[0134] Step 3: Add the first reinforcing raw material powder to the first mixture and stir for 3 minutes to disperse it evenly, thus obtaining the second mixture;

[0135] Step 4: Add the second reinforcing raw material powder to the second mixture and stir for 3 minutes to disperse it evenly, thus obtaining the third mixture;

[0136] Step 5: Add the gelation accelerator to the third mixture and stir thoroughly to obtain a sol;

[0137] Step 6: After shaping the sol, place it at 25°C and let it stand for 24 hours to obtain a gel;

[0138] Step 7: Place the gel in a 60°C oven without forced air and dry for 3 days to obtain the gel material.

[0139] The cementitious material in this embodiment has a porosity of 10.5%–11.5%, a water absorption rate of 7.5%–8.5%, and a density of 1.6–1.8 g / cm³. 3 It has a hardness of 21.4–22.3 HV, a compressive strength of 65.8–68.7 MPa, and good integrity.

[0140] Comparative Example 1

[0141] Comparative Example 1 discloses a cementitious material prepared using the same raw materials as in Example 1 and substantially the same method, except that:

[0142] The mass of the gelation promoter was changed to 12% of the mass of the silica sol.

[0143] Figure 2 The image shown is an optical image of the cementitious material in this comparative example. It can be seen that the surface of the cementitious material in this comparative example contains small particles and has several cracks, indicating poor integrity.

[0144] The comparative cementitious material had a porosity of 11.8%–12.5%, a water absorption rate of 8.9%–9.8%, and a density of 1.6–1.8 g / cm³. 3 It has a hardness of 20.9–22.9 HV and a compressive strength of 65.2–68.9 MPa. Its integrity is poor, with several cracks on the surface.

[0145] Comparative Example 2

[0146] Comparative Example 2 discloses a gelling material prepared using the same raw materials and substantially the same method as in Example 2, with the difference being:

[0147] In step 7, the drying temperature is changed from 60℃ to 100℃.

[0148] Figure 4 The image shown is an SEM image of the cementitious material in this comparative example. It can be seen that the cementitious material in this comparative example has good density, but there are many cracks, resulting in low strength.

[0149] The comparative cementitious material had a porosity of 12.1%–12.7%, a water absorption rate of 9.5%–10.2%, and a density of 1.6–1.7 g / cm³. 3 It has a hardness of 19.1–20.2 HV and a compressive strength of 64.1–65.9 MPa. Its integrity is poor, and it breaks into several small pieces.

[0150] Comparative Example 3

[0151] Comparative Example 3 discloses a cementitious material prepared using the same raw materials as in Example 2 and substantially the same method, except that:

[0152] Step 2 is removed, meaning the silane coupling agent KH-570 is not added.

[0153] Figure 5 The image shown is an optical image of the cementitious material in this comparative example. It can be seen that the cementitious material in this comparative example has a large crack and poor integrity.

[0154] The comparative example cementitious material has a porosity of 15.3%–16.5%, a water absorption rate of 12.3%–13.1%, and a density of 1.4–1.5 g / cm³. 3 It has a hardness of 16.1–16.8 HV and a compressive strength of 53.2–56.6 MPa. Its integrity is poor, with a large crack present.

[0155] Comparative Example 4

[0156] Comparative Example 4 discloses the preparation of a cementitious material using the same raw materials as in Example 2, with the difference being:

[0157] Swap the order of steps 3 and 4.

[0158] The comparative cementitious material had a porosity of 13.7%–14.2%, a water absorption rate of 10.6%–11.1%, and a density of 1.5–1.6 g / cm³. 3 It has a hardness of 18.2–18.9 HV and a compressive strength of 58.5–60.7 MPa. It has poor integrity and large cracks on the surface.

[0159] Comparative Example 5

[0160] Comparative Example 5 discloses the preparation of a cementitious material using the same raw materials as in Example 3, with the difference being:

[0161] Steps 3 and 4 are combined into one step, that is, the first reinforcing raw material powder and the second reinforcing raw material powder are added at the same time.

[0162] The comparative example cementitious material has a porosity of 14.4%–15.6%, a water absorption rate of 11.5%–12.6%, and a density of 1.4–1.6 g / cm³. 3 It has a hardness of 16.6–17.9 HV and a compressive strength of 55.2–58.2 MPa. It has poor integrity and large cracks on the surface.

[0163] Table 1 below shows a comparison of the relevant parameters of the gelling materials from Examples 1-6 and Comparative Examples 1-5. As can be seen from Table 1, using the same matrix and gelation accelerator, and the same preparation method, increasing the amount of gelation accelerator, using a higher drying temperature, and omitting the addition of the silane coupling agent modifier will lead to increased porosity, increased water absorption, decreased density, decreased hardness, decreased compressive strength, and compromised integrity of the prepared gelling materials. Even with the same matrix and gelation accelerator, different order of material addition will also result in compromised integrity of the prepared gelling materials.

[0164] The comparison table of relevant parameters for Examples 1-6 and Comparative Examples 1-5 is shown in Table 1 below.

[0165] Table 1 Relevant parameters of cementitious materials

[0166]

[0167]

[0168] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength, high-temperature resistant cementitious material, characterized in that, include: Step 1: Stir the silica sol to disperse it evenly; Step 2: Add the silane coupling agent to the silica sol and stir thoroughly until the mixture is homogeneous to obtain the first mixture. Step 3: Add the first reinforcing raw material powder to the first mixture and stir thoroughly until it is evenly dispersed to obtain the second mixture; Step 4: Add the second reinforcing raw material powder to the second mixture and stir thoroughly until it is evenly dispersed to obtain the third mixture; Step 5: Add the gelation accelerator to the third mixture and stir thoroughly to obtain a sol; Step 6: After shaping the sol, let it stand and age to obtain a smooth gel. Step 7: Place the gel in an oven to dry, and obtain a high-strength, high-temperature resistant gelling material.

2. The preparation method according to claim 1, characterized in that, In step 1, the silica sol is an alkaline silica sol.

3. The preparation method according to claim 1, characterized in that, In step 2, the mass of the silane coupling agent is 1% to 3% of the mass of the silica sol.

4. The preparation method according to claim 1, characterized in that, In step 3, the first reinforcing raw material powder is made of a high-strength and water-resistant material.

5. The preparation method according to claim 4, characterized in that, In step 3, the first reinforcing raw material powder includes one or more of calcium carbonate, calcium hydroxide, barium sulfate, and barium carbonate.

6. The preparation method according to claim 1, characterized in that, In step 4, the second reinforcing raw material powder includes one or more of aluminum hydroxide, kaolin, acidified dry adhesive powder, and nano-alumina.

7. The preparation method according to claim 1, characterized in that, In step 5, the gelation accelerator is calcium sulfate; the mass of the gelation accelerator is 7% to 10% of the mass of the silica sol.

8. The preparation method according to claim 1, characterized in that, In steps 3, 4 and 5, the mass ratio of the first reinforcing raw material powder, the second reinforcing raw material powder and the gelation accelerator is (22-54):(15-63):

100.

9. The preparation method according to any one of claims 1 to 8, characterized in that, In step 6, the temperature for static aging is 20-30℃, and the time is 12-24h.

10. A high-strength, high-temperature resistant cementitious material, characterized in that, The high-strength, high-temperature resistant cementitious material is prepared using the preparation method described in any one of claims 1 to 9.

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