Preparation method of porous material doped magnesium cementing material
By incorporating high-temperature treated porous materials such as molecular sieves or activated carbon into magnesium cementitious materials, the problem of surface pore formation in magnesium cementitious materials is solved by utilizing their microporous structure to capture air bubbles, thereby improving the appearance quality and mechanical properties.
Patent Information
- Application Number
- CN202511025826.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-24
- Publication Date
- 2025-12-02
AI Technical Summary
Existing technologies are insufficient to effectively prevent the formation of pores on the surface of magnesium cementitious materials, leading to a decline in appearance and mechanical properties. Chemical defoamers also affect complex hydration reactions and have limited effectiveness.
High-temperature treated porous materials, such as molecular sieves or activated carbon, are incorporated into magnesium oxysulfate cementitious materials. Their microporous structure serves as nucleation points for bubbles, capturing them through a physical adsorption mechanism. This prevents bubble aggregation, forms a physical barrier, and hinders the migration of bubbles to the surface.
It significantly reduced the number and size of pores on the surface of magnesium cementitious materials, improved the appearance quality and mechanical properties, avoided the incompatibility problem of chemical defoamers with the system, and enhanced the overall performance of the specimens.
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Figure CN121043232A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing a porous material-doped magnesium cementitious material. Background Technology
[0002] In actual production and application, the inherent defects of magnesium oxysulfate cement have consistently hindered its marketization and expansion into high-end applications. Among these defects, surface porosity not only affects the smoothness, density, and decorative appearance of magnesium oxysulfate boards, but also negatively impacts the adhesion and uniformity of subsequent finishing materials, easily leading to poor bonding or uneven surface texture. Furthermore, it adversely affects the mechanical properties, flexural strength, waterproofing, moisture resistance, and sound insulation of the boards.
[0003] Surface porosity is a common problem in the molding process of magnesium-based cementitious materials, not limited to magnesium oxysulfate cement. The root cause lies in the fact that magnesium-based cementitious materials are complex ternary component systems. The formation of products during hydration is highly complex and dynamically balanced, leading to potential interconversions between hydrated phases, a process that is difficult to achieve completely uniformly. Furthermore, the non-uniformity of cement particles in the hydration reaction, especially the differences in reaction rates between different regions, causes localized temperature imbalances, which in turn affect gas solubility and release rates, forming bubbles that accumulate on the surface and create porosity.
[0004] Current technology uses a certain proportion of defoamer as a chemical additive to suppress the formation of pores on the surface of cementitious materials. However, this method involves a series of complex chemical reactions, which have an uncontrollable impact on hydration products and may interfere with complex hydration reaction pathways and product formation, making its long-term effects difficult to predict. Secondly, the effect of suppressing surface pores is limited, especially when deep bubbles rise to the surface and will condense on the specimen surface without human intervention. Furthermore, the mechanical properties of magnesium oxysulfate sheets obtained using defoamers are often not high. Summary of the Invention
[0005] Purpose of the invention: The purpose of this invention is to provide a method for preparing magnesium-based cementitious materials that can effectively avoid the formation of pores on the surface of cementitious materials.
[0006] Technical solution: The preparation method of the porous material-doped magnesium cementitious material of the present invention is as follows: the porous material after high temperature treatment is incorporated into the slurry of sulfur-oxygen magnesium cementitious material, and after mixing, aggregate is added to obtain mortar; the mortar is poured into a mold and vibrated to compact it until there are no visible air bubbles and no floating air bubbles within 5 seconds; after removing the air bubbles, it is subjected to standard air curing, demolded after curing, and continued to be cured until the curing age is reached to obtain a magnesium cementitious material specimen with a uniform surface and no air bubbles.
[0007] The slurry of the magnesium sulfate-oxygenated cementitious material is obtained by mixing light-burned magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5–9:1:12–14. The slurry also includes citric acid as an admixture; the amount of citric acid added is 0.5% of the mass of light-burned magnesium oxide; the added aggregate is ISO standard sand, and the amount of aggregate added is such that the sand-to-binder ratio is 2:1.
[0008] The porous material is a molecular sieve or activated carbon; the molecular sieve is a 4A, 5A, or X-type molecular sieve; the doping mass is based on the mass of light-burned magnesium oxide, and the doping amount of the porous material is 10-20% of the mass of light-burned magnesium oxide.
[0009] The processing temperature for porous materials should not be lower than 120℃, and the processing time should be 1 to 1.5 hours. After high-temperature pretreatment, the adsorbed water inside the porous materials can be removed, keeping the internal pores unobstructed.
[0010] Porous materials were incorporated into the slurry of magnesium oxysulfate cementitious material and stirred at 3000 rpm for 3 minutes to ensure uniform distribution of the porous materials within the slurry. This prevented uneven local dispersion of the material, which could generate internal stress and affect the mechanical properties of the specimen.
[0011] The mold is a steel mold with dimensions of 4×4×16cm. Before pouring in the slurry, a release agent is evenly brushed onto the surface of the steel mold. The release agent is an oil-based release agent. The purpose of evenly brushing a small amount of release agent is to make the specimen easier to separate from the steel mold during demolding.
[0012] Place the slurry on a vibrating table and vibrate it thoroughly for 3-5 minutes; the standard air curing time for the slurry should be no less than 1 day.
[0013] This invention utilizes porous molecular sieves as gasification nuclei, using their microporous structure to provide nucleation sites for bubbles, thereby controlling the distribution of bubbles, reducing the aggregation and expansion of bubbles on the surface of cementitious materials, and avoiding the formation of pores on the surface of cementitious materials.
[0014] This invention employs a method of doping with porous materials (such as molecular sieves), which differs from the aforementioned chemical defoaming method. Instead, it utilizes the physical adsorption mechanism of nanomaterials. The porous material acts as a micro-nano-level bubble trap in the slurry. Its internal nano-scale pores can actively adsorb and capture newly generated bubbles or gas introduced by stirring, forming a physical barrier that prevents bubbles from migrating and accumulating on the surface, thus significantly reducing the number and size of large millimeter-level pores on the surface.
[0015] Beneficial Effects: Compared with existing technologies, the present invention has the following significant advantages: The method of the present invention can effectively avoid the generation of pores on the surface of magnesium gel. The present invention utilizes a large number of micro and nanopores in porous materials such as molecular sieves. By utilizing the physical adsorption mechanism of porous nanomaterials, the internal nanoscale pores can actively adsorb and capture newly generated bubbles or gases introduced by stirring. The bubbles attach to the micropore surface of the porous material through nucleation, preventing them from migrating and accumulating to the surface, thus significantly reducing the number and size of large millimeter-sized pores on the surface, thereby improving the surface quality of the cementitious material specimens. The present invention can avoid the system incompatibility problems that occur when adding various chemical defoamers to the slurry, and can significantly improve the appearance quality and mechanical properties of the specimens. Attached Figure Description
[0016] Figure 1 The surface porosity of the magnesium cementitious material specimens prepared in Example 1 and Comparative Example 1 is shown; where a is the surface porosity of the magnesium cementitious material specimen prepared in Comparative Example 1 without the addition of molecular sieve; and b is the surface porosity of the magnesium cementitious material specimen prepared in Example 1 with the addition of molecular sieve.
[0017] Figure 2 The surface porosity of the magnesium cementitious material specimens prepared in Examples 2-7 and Comparative Examples 2-7 is shown. Detailed Implementation
[0018] Example 1
[0019] The preparation method of the porous material-doped magnesium cementitious material of the present invention is as follows:
[0020] To a magnesium sulfate-magnesium oxide cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-calcined magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, 10% 4A molecular sieve (pretreated at 120℃ for 1 hour by weight of light-calcined magnesium oxide) was added. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2:1. Rapid stirring was continued for 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for one day and then further cured to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 1 As shown in (a).
[0021] pass Figure 1 As can be seen intuitively, the porosity of the specimen prepared in Example 1 is greatly reduced compared with that in Comparative Example 1, and the surface is uniform and smooth. As shown in Table 1, the specimen prepared in Example 1 also has good mechanical properties.
[0022] Comparative Example 1
[0023] A method for preparing a magnesium-based cementitious material, specifically comprising:
[0024] To a magnesium sulfate-magnesium sulfate heptahydrate-water cementitious slurry composed of magnesium oxide:magnesium sulfate heptahydrate:water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-calcined magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, standard sand was added as aggregate to achieve a sand-to-cement ratio of 2:1. Rapid stirring was continued for another 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 1 As shown in (b).
[0025] pass Figure 1 It can be clearly seen that the specimen prepared in Comparative Example 1 has poor surface quality. Due to the large number of internal air bubbles, they cannot be effectively extracted or evenly dispersed, resulting in internal stress concentration and a significant reduction in mechanical properties compared to Example 1.
[0026] Example 2
[0027] The preparation method of the porous material-doped magnesium cementitious material of the present invention is as follows:
[0028] To a magnesium sulfate-magnesium sulfate cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-calcined magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, 10% 5A molecular sieve (pretreated at 120℃ for 1 hour by weight of light-calcined magnesium oxide) was added. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2:1. Rapid stirring was continued for 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (a).
[0029] pass Figure 2 It can be seen that the surface of the specimen prepared in Example 2 is smooth and free of bubbles, and has good appearance quality; as shown in Table 1, the specimen prepared in Example 2 has good mechanical properties.
[0030] Example 3
[0031] The preparation method of the porous material-doped magnesium cementitious material of the present invention is as follows:
[0032] To a magnesium sulfate-magnesium sulfate cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, 10% X-type molecular sieve (by weight of light-burned magnesium oxide), which had undergone high-temperature pretreatment at 120℃ for 1 hour, was added. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2:1. Rapid stirring was continued for 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (b).
[0033] pass Figure 2 It can be seen that the surface of the specimen prepared in Example 3 is smooth and free of bubbles, and has good appearance quality; as shown in Table 1, the specimen prepared in Example 3 has good mechanical properties.
[0034] Example 4
[0035] The preparation method of the porous material-doped magnesium cementitious material of the present invention is as follows:
[0036] To a magnesium sulfate-magnesium oxide cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, activated carbon (by weight of light-burned magnesium oxide) was added, followed by standard sand as aggregate, bringing the sand-to-cement ratio to 2:1. Rapid stirring was continued for 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (c).
[0037] pass Figure 2 It can be seen that the surface of the specimen prepared in Example 4 is smooth and free of bubbles, and has good appearance quality; as shown in Table 1, the specimen prepared in Example 4 has good mechanical properties.
[0038] Example 5
[0039] The preparation method of the porous material-doped magnesium cementitious material of the present invention is as follows:
[0040] To a magnesium sulfate-magnesium sulfate cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, 20% 4A molecular sieve (by weight of light-burned magnesium oxide) was added. The molecular sieve was pretreated at 120℃ for 1 hour. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2:1. Rapid stirring was continued for 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (d).
[0041] pass Figure 2 It can be seen that the specimen prepared in Example 5 has a smooth surface, a small amount of bubbles, and good appearance quality; as shown in Table 1, the specimen prepared in Example 5 has good mechanical properties.
[0042] Example 6
[0043] The preparation method of the porous material-doped magnesium cementitious material of the present invention is as follows:
[0044] To a magnesium sulfate-magnesium sulfate cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, 10% 4A molecular sieve (pretreated at 120℃ for 1 hour by weight of light-burned magnesium oxide) was added. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2.5:1. Rapid stirring continued for 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (e).
[0045] pass Figure 2 It can be seen that the surface of the specimen prepared in Example 6 is smooth and free of bubbles, and has good appearance quality; as shown in Table 1, the specimen prepared in Example 6 has good mechanical properties.
[0046] Example 7
[0047] The preparation method of the porous material-doped magnesium cementitious material of the present invention is as follows:
[0048] To a magnesium sulfate-magnesium oxide cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, 10% 4A molecular sieve (pretreated at 120°C for 1 hour by weight of light-burned magnesium oxide) was added. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 1:1. Rapid stirring was continued for 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (f).
[0049] pass Figure 2 It can be seen that the surface of the specimen prepared in Example 7 is smooth and free of bubbles, and has good appearance quality; as shown in Table 1, the specimen prepared in Example 7 has good mechanical properties.
[0050] Comparative Example 2
[0051] A method for preparing a porous, doped magnesium cementitious material, specifically comprising:
[0052] To a magnesium sulfate-magnesium oxide cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-calcined magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, 5% 4A molecular sieve (pretreated at 120℃ for 1 hour by weight of light-calcined magnesium oxide) was added. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2:1. Rapid stirring continued for 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (g).
[0053] When only 5% of 4A molecular sieve is added, through Figure 2 It can be seen that the surface bubble defects of the specimen prepared in Comparative Example 2 were improved, but some still existed, resulting in a decrease in the mechanical properties of the specimen compared with Example 1, as shown in Table 1.
[0054] Comparative Example 3
[0055] A method for preparing a porous, doped magnesium cementitious material, specifically comprising:
[0056] To a magnesium sulfate-magnesium sulfate cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) was added. After rapid stirring at 3000 rpm for 3 minutes, 30% 4A molecular sieve (pretreated at 120℃ for 1 hour by weight of light-burned magnesium oxide) was added. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2:1. Rapid stirring was continued for 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (h).
[0057] When 30% of 4A molecular sieve is added, through Figure 2 It can be seen that although the specimen prepared in Comparative Example 3 had no obvious bubbles on the surface, the excessive amount of molecular sieve led to uneven distribution and surface microcracks. As a result, the mechanical properties of the specimen were also reduced compared to Example 1, as shown in Table 1.
[0058] Comparative Example 4
[0059] A magnesium oxysulfate cementitious material with added chemical defoamer, specifically:
[0060] To a magnesium sulfate-magnesium sulfate cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) and 2% A10 defoamer (by weight of light-burned magnesium oxide) were added. After rapid stirring at 3000 rpm for 3 minutes, standard sand was added as aggregate, controlling the sand-to-cement ratio of the slurry to be 2:1. Rapid stirring was continued for another 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for 1 day and then cured for another 7 days to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (i).
[0061] Add 2% defoamer, through Figure 2 It can be seen that the surface porosity of the specimen prepared in Comparative Example 4 was improved. However, due to the addition of chemical defoamer, the bubbles became larger and accumulated to the surface. If they were not removed in time before solidification, they would remain on the side surface of the specimen, affecting the appearance quality and also hindering the development of early strength.
[0062] Comparative Example 5
[0063] A method for preparing a porous, doped magnesium cementitious material, specifically comprising:
[0064] To a magnesium sulfate-magnesium oxide cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) was added. After stirring at 3000 rpm for 3 minutes, 10% 4A molecular sieve (by weight of light-burned magnesium oxide, without high-temperature pretreatment) was added. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2:1. The mixture was then stirred rapidly for another 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for one day and then further cured to obtain cementitious material specimens. The appearance of the specimens is shown in the image below. Figure 2 As shown in (j).
[0065] After adding 10% of 4A molecular sieve that has not undergone high-temperature pretreatment, it is passed through... Figure 2 It can be seen that the surface porosity has been improved but defects still exist. This may be because the pore structure on the molecular sieve surface is not fully activated, making it difficult to effectively capture bubbles or form bubble nucleation sites, thus affecting surface quality. In addition, the presence of bubbles and poor interparticle contact lead to local slippage, which limits its mechanical properties.
[0066] Comparative Example 6
[0067] A method for preparing a porous, doped magnesium cementitious material, specifically comprising:
[0068] To a magnesium sulfate-magnesium sulfate cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) was added. After stirring at 3000 rpm for 3 minutes, 10% 5A molecular sieve (by weight of light-burned magnesium oxide) was added without high-temperature pretreatment. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2:1. The mixture was then stirred rapidly for another 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for one day and then further cured to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (k).
[0069] Add 10% of 5A molecular sieve that has not undergone high-temperature pretreatment, and then... Figure 2 It can be seen that the surface porosity has improved but some defects still exist, which may be due to the same reason as Comparative Example 5.
[0070] Comparative Example 7
[0071] A method for preparing a porous, doped magnesium cementitious material, specifically comprising:
[0072] To a magnesium sulfate-magnesium sulfate cementitious material slurry composed of magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5:1:12, 0.5% citric acid (by weight of light-burned magnesium oxide) was added. After stirring at 3000 rpm for 3 minutes, 10% X-type molecular sieve (by weight of light-burned magnesium oxide) was added without high-temperature pretreatment. Standard sand was then added as aggregate to achieve a sand-to-cement ratio of 2:1. The mixture was then stirred rapidly for another 2 minutes to ensure uniform mixing. The slurry was poured into a steel mold evenly coated with a small amount of release agent. After vibration and smoothing, the slurry was demolded after curing for one day and then further cured to obtain cementitious material specimens. The appearance of the specimens is shown in the figure below. Figure 2 As shown in (l).
[0073] Add 10% X-type molecular sieve that has not undergone high-temperature pretreatment, and then... Figure 2 It can be seen that the surface porosity has improved but some defects still exist, which may be due to the same reason as Comparative Example 5.
[0074] Mechanical properties were tested on specimens from Examples 1-7 and Comparative Examples 1-7 after curing under standard air curing conditions for 7 days. The test results are shown in Table 1.
[0075] Table 1
[0076]
[0077]
[0078] This invention utilizes the effective microporous structure of molecular sieves pretreated at high temperatures to guide the uniform nucleation of bubbles, reducing surface porosity of the specimens. It eliminates the need for chemical defoamers, avoiding the negative impact of chemical defoamers on the gelation system, and significantly improving the appearance quality and mechanical properties of the specimens.
Claims
1. A method for preparing a porous material-doped magnesium cementitious material, characterized in that, Specifically, the porous material after high-temperature treatment is mixed into the slurry of magnesium oxysulfate cementitious material, and after mixing, aggregate is added to obtain mortar; the mortar is poured into a mold and vibrated to compact it until there are no visible air bubbles; after removing the air bubbles, it is subjected to standard air curing, demolded after curing, and continued to be cured until the curing age is reached, resulting in a magnesium cementitious material with a uniform surface and no air bubbles.
2. The preparation method according to claim 1, characterized in that: The magnesium sulfate-oxygenated cementitious material slurry is obtained by mixing lightly calcined magnesium oxide, magnesium sulfate heptahydrate, and water in a molar ratio of 8.5–9:1:12–14.
3. The preparation method according to claim 1, characterized in that: The porous material is a molecular sieve or activated carbon.
4. The preparation method according to claim 4, characterized in that: The molecular sieve is 4A, 5A, or X molecular sieve.
5. The preparation method according to claim 4, characterized in that: The amount of porous material doped with light-burned magnesium oxide is 10-20% of the mass of light-burned magnesium oxide.
6. The preparation method according to claim 1, characterized in that: The processing temperature for porous materials is not lower than 120℃, and the processing time is 1 to 1.5 hours.
7. The preparation method according to claim 1, characterized in that: The porous material is incorporated into the slurry of the magnesium oxysulfate cementitious material and stirred at a speed of not less than 3000 rpm for 3 to 5 minutes.
8. The preparation method according to claim 1, characterized in that: The added aggregate is ISO standard sand, and the amount of aggregate added is such that the sand-to-binder ratio is 1 to 2.5:
1.
9. The preparation method according to claim 1, characterized in that: The mold is a steel mold. Before the slurry is poured in, a release agent is evenly brushed onto the surface of the steel mold. The release agent is an oil-based release agent.
10. The preparation method according to claim 1, characterized in that: Place the slurry on a vibrating table and vibrate it thoroughly for 3-5 minutes; the standard air curing time for the slurry should be no less than 1 day.