A composite material cooperated with wollastonite fiber modified high-temperature-resistant cementitious material, a preparation method and application thereof

Abstract

This invention relates to the field of cementitious materials technology, and particularly to a high-temperature resistant cementitious material modified with wollastonite fiber using a multiphase material, its preparation method, and its application. The high-temperature resistant cementitious material modified with wollastonite fiber using a multiphase material is characterized by comprising the following raw materials in parts by weight: 33-38.5 parts slag, 27-32 parts metakaolin, 20-30 parts wollastonite fiber, 8-12 parts calcined dolomite, 7-18 parts calcium hexaaluminate-magnesium aluminum spinel multiphase material, 30-32 parts alkali activator, and 55-60 parts water. The preparation method of the calcium hexaaluminate-magnesium aluminum spinel multiphase material is as follows: dolomite and alumina are ball-milled, dried, pressed into shape, sintered, and then ground. In this invention, wollastonite fiber and calcium hexaaluminate-magnesium aluminum spinel multiphase material exert a synergistic effect of chemical silicon supplementation, physical filling, and optimization of gel composition to jointly promote the improvement of the high-temperature resistance of the composite activated cementitious material.

Description

Technical Field

[0001] This invention relates to the field of cementitious materials technology, and in particular to a high-temperature resistant cementitious material modified by wollastonite fiber with a multiphase material, its preparation method and application. Background Technology

[0002] Traditional silicate cement-based cementitious materials are prone to rapid strength degradation at high temperatures due to the decomposition of hydration products, increased porosity, and concentrated thermal stress. Although alkali-activated cementitious materials (such as slag-metakaolin systems) have relatively good heat resistance due to the absence of ettringite structure, their high-temperature performance still has significant shortcomings: at temperatures above 800℃, the gel structure of alkali-activated cementitious materials undergoes dehydration and condensation, leading to the propagation of microcracks. Simultaneously, the transformation of the amorphous phase to the crystalline phase is accompanied by volume shrinkage, causing structural collapse. At high temperatures, the porosity of the matrix increases, lacking rigid skeletal support, and the residual strength is generally below 30% (1000℃). Single fillers are difficult to coordinate with low thermal expansion coefficients and high melting point characteristics, easily generating interfacial stress with the matrix.

[0003] Current modification techniques (such as adding alumina micro powder, fibers, etc.) can partially improve high-temperature performance, but they have the following limitations: although single mineral phases (such as corundum) have high melting points, their coefficients of thermal expansion differ greatly from those of the matrix, and the high-temperature interface is easily peeled off; conventional particulate fillers have limited filling effect on pores and are difficult to suppress the propagation of high-temperature cracks. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing a multiphase material synergistic with wollastonite fiber modified high-temperature resistant cementitious material, its preparation method, and its application.

[0005] The first objective of this invention is to provide a high-temperature resistant cementitious material modified by wollastonite fiber in conjunction with a multiphase material, comprising the following raw materials in parts by weight: 33-38.5 parts slag, 27-32 parts metakaolin, 20-30 parts wollastonite fiber, 8-12 parts calcined dolomite, 7-18 parts calcium hexaaluminate-magnesium aluminum spinel multiphase material, 30-32 parts alkali activator, and 55-60 parts water;

[0006] The preparation method of calcium hexaaluminate-magnesium aluminum spinel multiphase material is as follows: dolomite and alumina are ball-milled, dried, pressed into shape, sintered, and then ground.

[0007] Further, the raw materials include the following parts by weight: 33-38.5 parts slag, 27-31.5 parts metakaolin, 20-30 parts wollastonite, 10 parts calcined dolomite, 7.5-17.5 parts calcium hexaaluminate-magnesium aluminum spinel multiphase material, 31.69 parts alkali activator, and 60 parts water.

[0008] Furthermore, in the preparation method of calcium hexaaluminate-magnesium aluminum spinel multiphase material, the mass ratio of dolomite to alumina is 10~30: 80~100.

[0009] Furthermore, in the preparation method of calcium hexaaluminate-magnesium aluminum spinel multiphase material, the sintering mechanism is 1500℃~1600℃ for 2~4h.

[0010] Furthermore, the alkaline activator is a nano-based alkaline solution activator.

[0011] Furthermore, calcined dolomite is obtained by calcining dolomite at 800℃~1000℃ for 1h~2h.

[0012] Furthermore, the wollastonite fibers have a diameter of 2-20 micrometers and an aspect ratio greater than 10.

[0013] The second objective of this invention is to provide a method for preparing a high-temperature resistant cementitious material modified with wollastonite fiber in conjunction with the aforementioned multiphase material, comprising the following steps:

[0014] S1. Preparation of calcium hexaaluminate-magnesium aluminum spinel multiphase material;

[0015] S2. According to the mass ratio, slag, metakaolin, calcined dolomite powder, calcium hexaaluminate-magnesium aluminum spinel multiphase material and wollastonite fiber are mixed evenly to obtain dry mixture.

[0016] S3. Weigh the alkali activator and water, stir them thoroughly to make them evenly mixed, and then add them to the above dry mixture as an external admixture. Then transfer the slurry to a mold and cure it to obtain the multiphase material synergistic with wollastonite fiber modified high temperature resistant cementitious material.

[0017] Furthermore, it is cured at room temperature for 20~24 hours.

[0018] Furthermore, maintain a curing temperature of 20-25℃, a relative humidity of 90-95%, and a curing period of 3-28 days.

[0019] The second objective of this invention is to provide an application of the multiphase material as described above in conjunction with wollastonite fiber-modified high-temperature resistant cementitious materials, for use in high-temperature buildings and protective coatings.

[0020] In this invention, wollastonite fiber (WS) and calcium hexaaluminate-magnesium aluminum spinel (CA6-MA) composite material significantly improve the high-temperature performance of cementitious materials through a synergistic mechanism of physical reinforcement and chemical optimization. At the physical level, wollastonite fiber, with its high melting point and low coefficient of thermal expansion, maintains morphological stability at high temperatures, forming a three-dimensional network structure to bridge microcracks and disperse thermal stress, effectively inhibiting crack propagation. Simultaneously, the layered calcium hexaaluminate (CA6) in the CA6-MA composite material provides a rigid framework support for the matrix, while the magnesium aluminum spinel (MA) particles fill pores, reduce porosity, and inhibit the formation of interconnected pores, resulting in a dense matrix. Together, they construct a complementary "fiber-particle" reinforcement network, whose low coefficient of thermal expansion, matching the matrix, further uniformly disperses thermal stress, reduces thermal shock damage, and thus improves the high-temperature stability of the material. At the chemical level, wollastonite fiber releases active calcium and silicon ions in an alkaline environment, replenishing the silicon source required for the gelation reaction and promoting the formation of subsequent hydration products to increase matrix density; CA6-MA, on the other hand, releases Al... 3+ They participate in the reaction and optimize the stoichiometric composition of the gel phase. Under high-temperature conditions (such as 1000℃), they synergistically promote the formation of high-melting-point phases such as anorthite and nepheline, inhibit the decomposition of amorphous gel, delay mass loss, and thus improve the high-temperature stability of the material.

[0021] In summary, wollastonite fiber and calcium hexaaluminate-magnesium aluminum spinel composite material (CA6-MA composite material) exert a synergistic effect of chemical silicon supplementation, physical filling and optimized gel composition to jointly promote the improvement of high temperature resistance of composite activated cementitious materials. Attached Figure Description

[0022] Figure 1 This is a flowchart of the preparation method of the high-temperature resistant cementitious material modified by the multiphase material and wollastonite fiber according to the present invention. Detailed Implementation

[0023] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0024] Preparation of CA6-MA composite material particles

[0025] 20 parts of dolomite and 100 parts of alumina were placed in a ball mill and ground for 2 hours. The raw materials were then removed and transferred to an oven to dry. The dried powder was pressed into shape and sintered in a muffle furnace at 800°C for 1 hour. After sintering, the powder was ground to obtain CA6-MA multiphase material particles.

[0026] The optimal ratio of CA6-MA obtained by solid-state sintering of dolomite and neutral alumina is: 20 parts dolomite in 100 parts Al2O3. At this ratio, CA6-MA with the highest volume stability and purity can be synthesized.

[0027] The CA6-MA multiphase material particles prepared above were used in all the following examples. The slag was S95 slag, which was purchased from Gongyi Longze Water Purification Materials Co., Ltd., and the wollastonite fiber was purchased from Hunan Shanlin Shiyu Mineral Products Co., Ltd.

[0028] Example 1

[0029] A method for preparing a high-temperature resistant cementitious material modified with wollastonite fiber using multiphase materials includes the following steps:

[0030] S1: Weigh the raw materials according to the following proportions: 37.125 parts slag, 30.375 parts metakaolin, 10 parts calcined dolomite, 10 parts CA6-MA multiphase material, 22.5 parts wollastonite fiber, 31.69 parts alkali activator, and 60 parts water.

[0031] S2: Mix slag, metakaolin, calcined dolomite powder, CA6-MA multiphase material particles and wollastonite evenly according to the proportion to obtain a dry mixture.

[0032] S3: Weigh the alkali activator and deionized water, stir them thoroughly to make them evenly mixed, and then add them to the mixed powder obtained from S2 as an external admixture. After stirring in a high-speed disperser, transfer the slurry to a mold and cure it at room temperature for 24 hours.

[0033] S4: After demolding the block samples obtained in S3, place them in a standard curing chamber (temperature 20℃, relative humidity 95%) for curing for 3, 7, and 28 days. The 3-day, 7-day, and 28-day compressive strength of each example were tested according to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)".

[0034] S5: Place the block samples cured for 28 days in a muffle furnace (SX-3-10) for calcination, setting different calcination temperature gradients. After calcination, turn off the heating system and allow the samples to cool naturally to room temperature with the furnace. After cooling, remove the samples for compressive strength analysis.

[0035] The compressive strength test results of the cementitious material in Example 1 are shown in Table 1.

[0036] The results of the residual compressive strength test of the cementitious material after calcination in Example 1 are shown in Table 2.

[0037] Example 2

[0038] A high-temperature resistant cementitious material modified with wollastonite fiber by a multiphase material was prepared. The raw material composition was as follows: 34.375 parts slag, 28.125 parts metakaolin, 10 parts calcined dolomite, 10 parts CA6-MA multiphase material, 27.5 parts wollastonite fiber, 31.69 parts alkali activator, and 60 parts water.

[0039] All other processes are the same as in Example 1.

[0040] The compressive strength test results of the cementitious material in Example 2 are shown in Table 1.

[0041] The results of the residual compressive strength test of the cementitious material after calcination in Example 2 are shown in Table 2.

[0042] Example 3

[0043] A high-temperature resistant cementitious material modified with wollastonite fiber by a multiphase material was prepared. The raw material composition was as follows: 37.125 parts slag, 30.375 parts metakaolin, 10 parts calcined dolomite, 15 parts CA6-MA multiphase material, 22.5 parts wollastonite fiber, 31.69 parts alkali activator, and 60 parts water.

[0044] All other processes are the same as in Example 1.

[0045] The compressive strength test results of the cementitious material in Example 3 are shown in Table 1.

[0046] The results of the residual compressive strength test of the cementitious material after calcination in Example 3 are shown in Table 2.

[0047] Example 4

[0048] A high-temperature resistant cementitious material modified with wollastonite fiber by a multiphase material was prepared. The raw material composition was as follows: 34.375 parts slag, 28.125 parts metakaolin, 10 parts calcined dolomite, 15 parts CA6-MA multiphase material, 27.5 parts wollastonite fiber, 31.69 parts alkali activator, and 60 parts water.

[0049] All other processes are the same as in Example 1.

[0050] The compressive strength test results of the cementitious material in Example 4 are shown in Table 1.

[0051] The results of the residual compressive strength test of the cementitious material after calcination in Example 4 are shown in Table 2.

[0052] Example 5

[0053] A high-temperature resistant cementitious material modified with wollastonite fiber by a multiphase material was prepared. The raw material composition was as follows: 38.5 parts slag, 31.5 parts metakaolin, 10 parts calcined dolomite, 12.5 parts CA6-MA multiphase material, 20 parts wollastonite fiber, 31.69 parts alkali activator, and 60 parts water.

[0054] All other processes are the same as in Example 1.

[0055] The compressive strength test results of the cementitious material in Example 5 are shown in Table 1.

[0056] The residual compressive strength test results of the cementitious material in Example 5 after calcination are shown in Table 2.

[0057] Example 6

[0058] A high-temperature resistant cementitious material modified with wollastonite fiber by a multiphase material was prepared. The raw material composition was as follows: 35.75 parts slag, 29.25 parts metakaolin, 10 parts calcined dolomite, 7.5 parts CA6-MA multiphase material, 25 parts wollastonite fiber, 31.69 parts alkali activator, and 60 parts water.

[0059] All other processes are the same as in Example 1.

[0060] The compressive strength test results of the cementitious material in Example 6 are shown in Table 1.

[0061] The residual compressive strength test results of the cementitious material in Example 6 after calcination are shown in Table 2.

[0062] Comparative Example 1

[0063] The mass fractions of the raw material components are shown in Table 3.

[0064] All other processes are the same as in Example 1.

[0065] The compressive strength test results of the cementitious material in Comparative Example 1 are shown in Table 4.

[0066] The residual compressive strength test results of the cementitious material of Comparative Example 1 after calcination are shown in Table 5.

[0067] Comparative Example 2

[0068] The mass fractions of the raw material components are shown in Table 6.

[0069] All other processes are the same as in Example 1.

[0070] The compressive strength test results of the cementitious material in Comparative Example 2 are shown in Table 7.

[0071] The residual compressive strength test results of the cementitious material of Comparative Example 2 after calcination are shown in Table 8.

[0072] Table 1. Test results of compressive strength of cementitious materials in Examples 1-6

[0073]

[0074] Table 2. Residual compressive strength of cementitious materials at different calcination temperatures after 28 days

[0075]

[0076] Table 3

[0077]

[0078] Table 4

[0079]

[0080] Table 5

[0081]

[0082] Table 6

[0083]

[0084] Table 7

[0085]

[0086] Table 8

[0087]

[0088] As can be seen from the table data above, in this invention, WS wollastonite fiber and CA6-MA multiphase material mainly exert a synergistic effect of chemical silica supplementation, physical filling, and optimized gel composition to jointly promote the improvement of the high-temperature resistance of the composite activated cementitious material. Wollastonite or CA6-MA multiphase material alone exhibits poor strength after reaching 1000℃. Example 6 at room temperature showed the best compressive strength in the later stages of curing, with a 28-day strength increase of 14.29% compared to group FX, but exhibited the worst high-temperature resistance due to its relatively low total mineral content. Example 3 showed the best high-temperature resistance, with its residual compressive strength remaining at 72.11% at 1000℃.

[0089] For any points not covered above, existing technologies shall apply.

[0090] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite material synergistically modified with wollastonite fibers for high temperature resistant cementitious material, characterized in that, The raw materials include the following parts by weight: 33-38.5 parts slag, 27-32 parts metakaolin, 20-30 parts wollastonite fiber, 8-12 parts calcined dolomite, 7-18 parts calcium hexaaluminate-magnesium aluminum spinel multiphase material, 30-32 parts alkali activator, and 55-60 parts water. The preparation method of calcium hexaaluminate-magnesium aluminum spinel multiphase material is as follows: dolomite and alumina are ball-milled, dried, pressed into shape, sintered, and then ground.

2. The high-temperature resistant cementitious material modified with wollastonite fiber as described in claim 1, characterized in that, The raw materials include the following parts by weight: 33-38.5 parts slag, 27-31.5 parts metakaolin, 20-30 parts wollastonite, 10 parts calcined dolomite, 7.5-17.5 parts calcium hexaaluminate-magnesium aluminum spinel multiphase material, 31.69 parts alkali activator, and 60 parts water.

3. The high-temperature resistant cementitious material modified with wollastonite fiber as described in claim 1, characterized in that, In the preparation method of calcium hexaaluminate-magnesium aluminum spinel multiphase material, the mass ratio of dolomite to alumina is 10~30: 80~100.

4. The high-temperature resistant cementitious material modified with wollastonite fiber as described in claim 1, characterized in that, In the preparation method of calcium hexaaluminate-magnesium aluminum spinel multiphase material, the sintering mechanism is 1500℃~1600℃, 2~4h.

5. The high-temperature resistant cementitious material modified with wollastonite fiber as described in claim 1, characterized in that, The alkaline activator is a sodium-based alkaline solution activator.

6. The high-temperature resistant cementitious material modified with wollastonite fiber as described in claim 1, characterized in that, Calcined dolomite is obtained by calcining dolomite at 800℃~1000℃ for 1h~2h.

7. The high-temperature resistant cementitious material modified with wollastonite fiber as described in claim 1, characterized in that, The wollastonite fibers have a diameter of 2-20 micrometers and an aspect ratio greater than 10.

8. A method for preparing a high-temperature resistant cementitious material modified with wollastonite fiber as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Preparation of calcium hexaaluminate-magnesium aluminum spinel multiphase material; S2. According to the mass ratio, slag, metakaolin, calcined dolomite powder, calcium hexaaluminate-magnesium aluminum spinel multiphase material and wollastonite fiber are mixed evenly to obtain dry mixture. S3. Weigh the alkali activator and water, stir them thoroughly to make them evenly mixed, and then add them to the above dry mixture as an external admixture. Then transfer the slurry to a mold and cure it to obtain the multiphase material synergistic with wollastonite fiber modified high temperature resistant cementitious material.

9. The preparation method according to claim 8, characterized in that, Curing at room temperature for 20-24 hours; The curing temperature is 20~25℃, the relative humidity is 90~95%, and the curing time is 3~28 days.

10. An application of a multiphase material as described in any one of claims 1-7, in conjunction with a wollastonite fiber-modified high-temperature resistant cementitious material, characterized in that... Applications include high-temperature construction and protective coatings.

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