Highly corrosion-resistant anti-permeation porous structure building new material and preparation method thereof

Abstract

The application discloses a kind of high corrosion-resistant anti-infiltration porous structure building new materials and preparation method thereof, belong to building material technical field.Building new materials include ordinary Portland cement, fly ash, slag powder, synergistic modified diatomite, vitrified microbead, polycarboxylate superplasticizer, silane hydrophobic agent and deionized water, wherein synergistic modified diatomite is prepared by sodium metaaluminate induced activation and sodium silicate mineralization synergistic modification.Through optimizing diatomite surface activity and pore structure, the interface bonding capacity of cement matrix is improved, the generation of hydration product is promoted, and the internal pore structure and density of the material are improved.The building new material prepared by the application has high compressive strength, excellent impermeability, low chloride ion permeability and water absorption, can significantly improve the service life of building material in humid, high salt and corrosive environment, and has good engineering application prospect.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a new type of highly corrosion-resistant and impermeable porous building material and its preparation method. Background Technology

[0002] As construction engineering expands into complex service environments such as marine engineering, underground engineering, bridges and tunnels, and chemical infrastructure, building materials are subjected to long-term corrosion from media such as chloride ions, sulfates, acid rain, and groundwater. They also endure the combined effects of various environmental factors, including wet-dry cycles, freeze-thaw cycles, and temperature fluctuations. This leads to problems such as steel reinforcement corrosion, cement cracking, pore connectivity, and structural deterioration, resulting in decreased building durability and shortened service life. Therefore, developing new building materials with high corrosion resistance, high impermeability, and good durability has become an important research direction in the field of building materials.

[0003] Currently, to improve the corrosion resistance and impermeability of building materials, mineral admixtures such as fly ash, slag powder, silica fume, and metakaolin are commonly added, or additives such as silane water-repellent agents and polycarboxylate superplasticizers are added to improve the internal structure of the material. Although these methods can refine the pore structure, reduce porosity, and improve the density of the material to some extent, the synergistic effect between different components is limited. A certain number of capillaries and microcracks still exist inside the material, and corrosive media can still continuously penetrate along the pore channels. This results in limited improvement in long-term corrosion resistance and impermeability, making it difficult to meet the high durability requirements of building structures in complex service environments.

[0004] On the other hand, diatomaceous earth possesses advantages such as large specific surface area, abundant porosity, good chemical stability, and low cost, making it a promising natural porous siliceous mineral. However, unmodified diatomaceous earth has low surface activity and weak interfacial bonding with cementitious matrices. Furthermore, its numerous open pores can easily increase water absorption when directly applied to building materials, negatively impacting the material's mechanical and durability properties. Therefore, this limits its further application in high-performance building materials.

[0005] In existing technologies, the modification of diatomaceous earth mostly employs single modification methods such as acid treatment, alkali treatment, or surface modification with silane coupling agents. While these methods can improve some properties of diatomaceous earth, their enhancement of pore structure stability, interfacial bonding ability, and synergistic effects with cement hydration products remains relatively limited. It is difficult to simultaneously improve the corrosion resistance, impermeability, and long-term durability of building materials. Therefore, developing a synergistic modification method that can effectively improve the interfacial activity and pore structure characteristics of diatomaceous earth and applying it to new high-corrosion-resistant and impermeable porous building materials is of significant practical importance for improving the comprehensive performance of building materials and extending the service life of engineering structures. Summary of the Invention

[0006] In order to overcome the technical problems of insufficient corrosion resistance and impermeability of building materials in the prior art, weak interfacial bonding between diatomite and cement matrix, limited optimization effect of pore structure, and poor long-term service durability, the present invention aims to provide a new high corrosion-resistant and impermeable porous building material and its preparation method.

[0007] To achieve the above objectives, this invention uses synergistically modified diatomaceous earth as a functional filler. Through sodium aluminate-induced activation and sodium silicate mineralization synergistic modification, the interfacial activity and pore structure stability of diatomaceous earth are improved. In addition, a multi-level dense protective system is constructed by combining ordinary silicate cement, fly ash, slag powder, vitrified microspheres, polycarboxylate superplasticizer and silane water-repellent agent, thereby preparing a new building material with high corrosion resistance and impermeability porous structure.

[0008] Compared with existing technologies, the new high corrosion-resistant and impermeable porous building material prepared by this invention has a denser pore structure, significantly improved corrosion resistance and impermeability, and also has good mechanical properties and long-term durability.

[0009] The objective of this invention can be achieved through the following technical solutions: A novel porous building material with high corrosion resistance and impermeability comprises the following raw materials in parts by weight: 100-150 parts of ordinary silicate cement; 20-60 parts of fly ash; 15-50 parts of slag powder; 8-30 parts of synergistically modified diatomaceous earth; 20-80 parts of vitrified microspheres; 0.2-2 parts of polycarboxylate superplasticizer; 0.2-2 parts of silane water-repellent agent; and 25-60 parts of deionized water. The synergistically modified diatomaceous earth is prepared by synergistic modification of diatomaceous earth through sodium aluminate-induced activation and sodium silicate mineralization.

[0010] Optionally, the synergistically modified diatomaceous earth comprises the following raw materials in parts by weight: 100-150 parts diatomaceous earth; 5-20 parts sodium aluminate; 8-25 parts sodium silicate; and 150-300 parts deionized water.

[0011] Optionally, the preparation method of synergistically modified diatomite includes the following steps: (1) Diatomaceous earth is acid-activated to obtain activated diatomaceous earth; (2) The activated diatomaceous earth is mixed with sodium aluminate to carry out an activation reaction, thereby obtaining aluminum-activated diatomaceous earth; (3) Aluminum-activated diatomite is mixed with sodium silicate for mineralization reaction, and then subjected to solid-liquid separation, washing, drying and pulverization to obtain the synergistically modified diatomite.

[0012] Optionally, the reaction conditions for step (1) are as follows: using a hydrochloric acid solution with a mass fraction of 5-10% as an acid activator, with a liquid-to-solid ratio of 3:1-8:1, stirring at 50-70°C for 2-4 hours, filtering, washing with deionized water until neutral, and then drying at 80-100°C for 6-10 hours.

[0013] Optionally, the reaction conditions in step (2) are as follows: the mass ratio of sodium aluminate to activated diatomite is 0.05:1 to 0.20:1, the reaction is stirred at 60 to 80°C for 2 to 4 hours, and the mixture is filtered and washed after the reaction is completed.

[0014] Optionally, the reaction conditions in step (3) are as follows: the mass ratio of sodium silicate to aluminum-activated diatomite is 0.08:1 to 0.25:1, the reaction is stirred at 70 to 90°C for 3 to 5 hours, after the reaction is completed, the mixture is filtered, washed, dried at 100 to 110°C for 8 to 12 hours, and pulverized to 100 to 200 mesh.

[0015] Optionally, the polycarboxylate superplasticizer is prepared by mixing a polycarboxylate superplasticizer mother liquor with a solid content of 35-45% with deionized water at a mass ratio of 1:(0.2-1); the silane hydrophobic agent is prepared by mixing isooctyltriethoxysilane with deionized water at a mass ratio of 1:(5-15).

[0016] Optionally, a method for preparing a new type of highly corrosion-resistant and impermeable porous building material includes the following steps: S1, ordinary silicate cement, fly ash, slag powder, synergistically modified diatomaceous earth and vitrified microspheres are added to the mixing equipment according to the proportion and mixed evenly to obtain a mixed powder; S2, mix polycarboxylate superplasticizer, silane water repellent agent and deionized water evenly to obtain a mixture; add the mixture to the mixed powder and continue stirring to obtain a uniform slurry; S3 involves injecting the slurry into a mold to form a new type of porous building material with high corrosion resistance and impermeability after settling, demolding, and curing.

[0017] Optionally, the reaction conditions for step S1 are: mixing with a horizontal forced mixer at a speed of 60-120 r / min for 5-10 min; and the reaction conditions for step S2 are: adding the mixture to the powder mixture at once, stirring at 150-300 r / min for 3-5 min, and then stirring at 300-600 r / min for 2-5 min to obtain a uniform slurry.

[0018] Optionally, the reaction conditions in step S3 are as follows: after the slurry is injected into the mold, it is vibrated for 30-90 seconds, allowed to stand for 12-24 hours, and then demolded. The slurry is then cured under standard conditions of 20±2℃ and relative humidity not less than 95% for 28 days to obtain the new high corrosion-resistant and impermeable porous structure building material.

[0019] The beneficial effects of this invention are: This invention employs a synergistic modification method of sodium aluminate-induced activation and sodium silicate mineralization to modify diatomaceous earth, thereby forming a stable aluminum-silicon active layer on the surface of the diatomaceous earth. This not only improves the surface activity of diatomaceous earth and its interfacial bonding ability with cement hydration products, but also promotes the in-situ growth of hydration products such as hydrated calcium silicate gel on the surface of diatomaceous earth during cement hydration. This enhances the interfacial adhesion between the components, reduces defects in the interfacial transition zone, and facilitates the formation of a more stable framework structure.

[0020] Simultaneously, the synergistic effect of modified diatomaceous earth with fly ash and slag powder in the pozzolanic reaction can continuously consume the calcium hydroxide produced by cement hydration, promote secondary hydration reaction, increase the amount of gel products generated, and fill and repair the capillaries and microcracks inside the material. Combined with vitrified microspheres to construct a multi-scale porous structure, it can improve the pore size distribution while ensuring the material is lightweight, and gradually transform the pores from interconnected pores to closed pores and micropores, thereby effectively reducing the penetration channels of corrosive media and improving the overall density of the material.

[0021] Polycarboxylate superplasticizers can reduce the water consumption of the system, improve the uniformity of slurry dispersion, and make the cement matrix form a denser microstructure. Silane hydrophobic agents form a stable hydrophobic layer on the internal pore walls and surface of the material, significantly reducing capillary water absorption and liquid water permeation rate. Together with synergistically modified diatomaceous earth, they form a dual protection mechanism of "internal densification + surface hydrophobicity", further hindering the migration of chloride ions, sulfates and other corrosive media into the material interior, and improving the corrosion resistance and impermeability of building materials in humid, high-salt and corrosive environments.

[0022] Therefore, this invention achieves simultaneous optimization of the microstructure and interface structure of the material through the synergistic effect of modified diatomaceous earth, multi-mineral admixtures and functional additives. While ensuring the material is lightweight, it significantly improves the corrosion resistance, impermeability, mechanical properties and long-term durability of building materials. It has the advantages of simple preparation process, wide availability of raw materials and strong engineering applicability, and can be widely used in marine engineering, underground engineering, bridges and tunnels and other building structures in complex corrosive environments. Attached Figure Description

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] Figure 1 A comparison chart showing the compressive strength test results of samples with different proportions. Detailed Implementation

[0025] The present invention will be further described below with reference to specific embodiments. However, the present invention is not limited to the following embodiments. Equivalent adjustments made without departing from the spirit and essence of the present invention should also be considered to fall within the protection scope of the present invention.

[0026] Example 1: This example aims to provide a new porous building material with high corrosion resistance and impermeability. By using the lower limit ratio of each raw material within the scope of the claims and combining it with the lower limit process conditions to prepare synergistically modified diatomite and new building materials, this example verifies that the technical solution of this invention can still achieve the optimization effect of synergistically modified diatomite on the pore structure and interface structure of cement-based materials under low addition conditions, thereby improving the corrosion resistance and impermeability of building materials.

[0027] S1. Preparation of Synergistically Modified Diatomite 100 parts of diatomaceous earth were weighed and added to 300 parts of a 5% hydrochloric acid solution, with a liquid-to-solid ratio of 3:1. The mixture was stirred at 50°C for 2 hours. After the reaction, the mixture was filtered and repeatedly washed with deionized water until the filtrate was neutral. The filtrate was then dried at 80°C for 6 hours to obtain activated diatomaceous earth. Subsequently, the activated diatomaceous earth was mixed with 5 parts of sodium aluminate and stirred at 60°C for 2 hours. After the reaction, the mixture was filtered and washed with deionized water to obtain aluminum-activated diatomaceous earth. The aluminum-activated diatomaceous earth was then mixed with 8 parts of sodium silicate for a mineralization reaction. The mixture was stirred at 70°C for 3 hours. After the reaction, the mixture was filtered, washed, and dried at 100°C for 8 hours. The diatomaceous earth was then pulverized and passed through a 100-mesh sieve to obtain synergistically modified diatomaceous earth. S2. Preparation of new porous building materials with high corrosion resistance and impermeability Weigh 100 parts of ordinary silicate cement, 20 parts of fly ash, 15 parts of slag powder, 8 parts of the above-prepared synergistic modified diatomaceous earth, and 20 parts of vitrified microspheres and add them to a horizontal forced mixer. Dry mix at 60 r / min for 5 min to obtain a mixed powder. Add 0.2 parts of polycarboxylate superplasticizer and 0.2 parts of silane water repellent to 25 parts of deionized water and mix evenly to obtain a mixed liquid. Add the mixed liquid to the mixed powder at once, stir at 150 r / min for 3 min, and then continue stirring at 300 r / min for 2 min to ensure that the slurry is fully mixed and homogeneous to obtain a uniform slurry. S3, Molding and Curing The obtained uniform slurry was injected into a pre-cleaned mold, compacted on a vibrating table for 30 seconds, allowed to stand for 12 hours, demolded, and then placed in a standard curing room with a temperature of 20±2℃ and a relative humidity of not less than 95% for 28 days to obtain a new porous building material with high corrosion resistance and impermeability.

[0028] Example 2: This example aims to provide a new porous building material with high corrosion resistance and impermeability. By using the median ratio of raw materials within the scope of the claims and combining it with median process conditions to prepare synergistically modified diatomaceous earth and the new building material, the advantages of sodium aluminate-induced activation and sodium silicate mineralization synergistic modification are fully utilized. This improves the interfacial bonding ability between the synergistically modified diatomaceous earth and the cement matrix, optimizes the internal pore structure of the material, and enables the new building material to possess excellent corrosion resistance, impermeability, and mechanical properties. This example is the preferred embodiment of the present invention.

[0029] S1. Preparation of Synergistically Modified Diatomite 125 parts of diatomaceous earth were weighed and added to 562.5 parts of a 7.5% hydrochloric acid solution, with a liquid-to-solid ratio of 4.5:1. The mixture was stirred at 60°C for 3 hours. After the reaction, the mixture was filtered and repeatedly washed with deionized water until the filtrate was neutral. The filtrate was then dried at 90°C for 8 hours to obtain activated diatomaceous earth. Subsequently, the activated diatomaceous earth was mixed with 12.5 parts of sodium aluminate and stirred at 70°C for 3 hours. After the reaction, the mixture was filtered and washed with deionized water to obtain aluminum-activated diatomaceous earth. The aluminum-activated diatomaceous earth was then mixed with 16.5 parts of sodium silicate for a mineralization reaction. The mixture was stirred at 80°C for 4 hours. After the reaction, the mixture was filtered, washed, and dried at 105°C for 10 hours. The resulting diatomaceous earth was then pulverized and passed through a 150-mesh sieve to obtain synergistically modified diatomaceous earth. S2. Preparation of new porous building materials with high corrosion resistance and impermeability Weigh 125 parts of ordinary silicate cement, 40 parts of fly ash, 32.5 parts of slag powder, 19 parts of the above-prepared synergistic modified diatomaceous earth, and 50 parts of vitrified microspheres and add them to a horizontal forced mixer. Dry mix at 90 r / min for 7 min to obtain a mixed powder. Add 1.1 parts of polycarboxylate superplasticizer and 1.1 parts of silane water repellent to 42.5 parts of deionized water and mix evenly to obtain a mixed liquid. Add the mixed liquid to the mixed powder at once, stir at 225 r / min for 4 min, and then continue stirring at 450 r / min for 3 min to ensure that the slurry is fully mixed and homogeneous to obtain a uniform slurry. S3, Molding and Curing The obtained uniform slurry was injected into a pre-cleaned mold, compacted on a vibrating table for 60 seconds, and then demolded after standing for 18 hours. It was then placed in a standard curing room with a temperature of 20±2℃ and a relative humidity of not less than 95% for 28 days to obtain a new porous building material with high corrosion resistance and impermeability.

[0030] Example 3: This example aims to provide a new high-corrosion-resistant and impermeable porous building material. By using the upper limit ratio of each raw material within the scope of the claims and combining it with the upper limit process conditions to prepare synergistically modified diatomite and new building materials, the activity of synergistically modified diatomite and its filling effect in cement matrix are further improved. The synergistic enhancement effect between mineral admixtures and functional additives is fully utilized to verify the improvement effect of the technical solution of the present invention on the corrosion resistance, impermeability and long-term durability of building materials under higher dosage conditions.

[0031] S1. Preparation of Synergistically Modified Diatomite 150 parts of diatomaceous earth were weighed and added to 1200 parts of a 10% hydrochloric acid solution, with a liquid-to-solid ratio of 8:1. The mixture was stirred at 70°C for 4 hours. After the reaction, the mixture was filtered and repeatedly washed with deionized water until the filtrate was neutral. The filtrate was then dried at 100°C for 10 hours to obtain activated diatomaceous earth. Subsequently, the activated diatomaceous earth was mixed with 20 parts of sodium aluminate and stirred at 80°C for 4 hours. After the reaction, the mixture was filtered and washed with deionized water to obtain aluminum-activated diatomaceous earth. The aluminum-activated diatomaceous earth was then mixed with 25 parts of sodium silicate for a mineralization reaction. The mixture was stirred at 90°C for 5 hours. After the reaction, the mixture was filtered, washed, and dried at 110°C for 12 hours. The resulting diatomaceous earth was pulverized and passed through a 200-mesh sieve to obtain synergistically modified diatomaceous earth. S2. Preparation of new porous building materials with high corrosion resistance and impermeability Weigh 150 parts of ordinary silicate cement, 60 parts of fly ash, 50 parts of slag powder, 30 parts of the above-prepared synergistic modified diatomaceous earth, and 80 parts of vitrified microspheres and add them to a horizontal forced mixer. Dry mix at 120 r / min for 10 min to obtain a mixed powder. Add 2 parts of polycarboxylate superplasticizer and 2 parts of silane water repellent to 60 parts of deionized water and mix evenly to obtain a mixed liquid. Add the mixed liquid to the mixed powder at once, stir at 300 r / min for 5 min, and then continue stirring at 600 r / min for 5 min to ensure that the slurry is fully mixed and homogeneous to obtain a uniform slurry. S3, Molding and Curing The obtained uniform slurry was injected into a pre-cleaned mold, compacted on a vibrating table for 90 seconds, and then demolded after standing for 24 hours. It was then placed in a standard curing room with a temperature of 20±2℃ and a relative humidity of not less than 95% for 28 days to obtain a new porous building material with high corrosion resistance and impermeability.

[0032] Comparative Example 1: This comparative example aims to verify the effect of sodium aluminate-induced activation and sodium silicate mineralization synergistic modification on the performance improvement of diatomaceous earth. Compared with Example 2, only the synergistically modified diatomaceous earth was replaced with unmodified natural diatomaceous earth, while the other raw material composition, proportions, and preparation processes remained the same.

[0033] S1. Treatment of natural diatomaceous earth Weigh 125 parts of natural diatomaceous earth, crush it, pass it through a 150-mesh sieve, dry it at 105℃ for 8 hours, and cool it to room temperature for later use. S2. Preparation of new porous building materials with high corrosion resistance and impermeability Weigh 125 parts of ordinary Portland cement, 40 parts of fly ash, 32.5 parts of slag powder, 19 parts of the above-mentioned natural diatomaceous earth, and 50 parts of vitrified microspheres and add them to a horizontal forced mixer. Dry mix at 90 r / min for 7 min to obtain a mixed powder. Add 1.1 parts of polycarboxylate superplasticizer and 1.1 parts of silane water repellent to 42.5 parts of deionized water and mix evenly to obtain a mixed liquid. Add the mixed liquid to the mixed powder at once, stir at 225 r / min for 4 min, and then continue stirring at 450 r / min for 3 min to obtain a uniform slurry. S3, Molding and Curing The obtained slurry was injected into the mold and vibrated for 60 seconds. After standing for 18 hours, it was demolded and cured under standard conditions of 20±2℃ and relative humidity not less than 95% for 28 days to obtain building material samples.

[0034] Comparative Example 2: This comparative example aims to verify the enhancing effect of synergistically modified diatomaceous earth on the overall performance of building materials. Compared with Example 2, only the synergistically modified diatomaceous earth was omitted, while the composition, proportions, and preparation process of other raw materials remained the same.

[0035] S1. Preparation of mixed powder Weigh 125 parts of ordinary Portland cement, 40 parts of fly ash, 32.5 parts of slag powder and 50 parts of vitrified microspheres and add them to a horizontal forced mixer. Dry mix at 90 r / min for 7 min to obtain a mixed powder. S2. Preparation of new porous building materials with high corrosion resistance and impermeability 1.1 parts of polycarboxylate superplasticizer and 1.1 parts of silane water repellent were added to 42.5 parts of deionized water and mixed evenly to obtain a mixture. The mixture was added to the powder mixture at once, and stirred at 225 r / min for 4 min, and then stirred at 450 r / min for 3 min to obtain a uniform slurry. S3, Molding and Curing The obtained slurry was injected into the mold and vibrated for 60 seconds. After standing for 18 hours, it was demolded and cured under standard conditions of 20±2℃ and relative humidity not less than 95% for 28 days to obtain building material samples.

[0036] Performance testing: 1. Compressive strength test Specimens were prepared according to GB / T17671—2021 "Test Method for Strength of Cement Mortar (ISO Method)". After standard curing for 28 days, the compressive strength of the specimens was tested using a computer-controlled electronic universal testing machine. The loading rate was controlled at 2.4 kN / s. Six parallel samples were tested for each group of specimens, and the average value was taken as the final test result. The compressive strength of the material is expressed in MPa. The higher the compressive strength, the denser the internal structure of the material and the better its mechanical properties.

[0037] 2. Impermeability test The impermeability test was conducted according to GB / T50082—2009, "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". Specimens cured for 28 days were placed in a concrete permeability tester. An initial pressure of 0.2 MPa was applied, increasing by 0.1 MPa every 8 hours until water seepage occurred. The maximum impermeability pressure the specimen could withstand was recorded, and the impermeability grade was calculated. Three sets of tests were conducted for each group of samples, and the average value was taken as the final test result. Higher impermeability pressure indicates a stronger ability of the material to prevent the penetration of moisture and corrosive media.

[0038] 3. Chloride ion permeation performance test Rapid chloride ion penetration tests were conducted according to ASTM C1202, "Test Method for Electrical Flux of Chloride Ion Penetration Resistance of Concrete". Cylindrical specimens cured for 28 days were placed in a rapid chloride ion penetration test apparatus, with one side filled with 3.0% NaCl solution and the other side filled with 0.3 mol / L NaOH solution. The test was conducted continuously at 60V DC for 6 hours, and the cumulative charge (Coulomb) was recorded. Three parallel samples were tested in each group, and the average value was taken as the final result. The lower the cumulative electrical flux, the stronger the material's resistance to chloride ion penetration and the better its corrosion resistance.

[0039] 4. Water absorption rate test Water absorption was tested according to GB / T50082—2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". After standard curing for 28 days, the specimens were dried at 105±5℃ to constant weight, and the dried weight was recorded. Subsequently, the specimens were completely immersed in deionized water at 20±2℃ for 48 hours. After removing and drying the surface moisture, the wet weight was measured, and the water absorption rate was calculated based on the dry and wet weights. Three sets of tests were conducted for each group of specimens, and the average value was taken as the final test result. The lower the water absorption rate, the lower the internal pore connectivity of the material, the denser the structure, and the better the impermeability.

[0040] Table 1. Performance test results of new building materials in different embodiments and comparative examples.

[0041] As shown in Table 1, the novel high-corrosion-resistant and impermeable porous building material prepared by this invention outperforms the comparative example in terms of compressive strength, impermeability, chloride ion penetration resistance, and water absorption. This indicates that the synergistic modification of diatomaceous earth can significantly improve the internal microstructure of the material and increase the density of the matrix, thereby comprehensively enhancing the mechanical properties and durability of the material. In particular, Example 2 achieved optimal performance in all aspects, indicating that the proportions of each component and the synergistic modification process were optimally matched.

[0042] The compressive strength test results showed that the compressive strengths of Examples 1-3 reached 58.2 MPa, 64.8 MPa, and 62.1 MPa, respectively, all significantly higher than those of Comparative Example 1 (53.8 MPa) and Comparative Example 2 (49.6 MPa), with Example 2 showing the most significant improvement. This is mainly because the synergistic modification by sodium aluminate activation and sodium silicate mineralization resulted in a more active silica-alumina structure on the diatomaceous earth surface, which can serve as nucleation sites for cement hydration products, promoting CSH gel formation. Simultaneously, it improved the interfacial transition zone between aggregate and paste, making the internal structure of the material more uniform and dense, thus significantly improving the overall compressive strength. When the amount of modified diatomaceous earth added was further increased to that of Example 3, the micropore filling tended to be saturated, and local particles were prone to agglomeration. Therefore, the compressive strength was slightly lower than that of Example 2, but still superior to Example 1 and the comparative examples.

[0043] The results of the impermeability tests showed that the impermeability pressures of Examples 1-3 reached 1.83 MPa, 2.31 MPa, and 2.12 MPa, respectively, all higher than those of the two comparative examples. Example 2 exhibited the highest impermeability pressure. This indicates that the synergistically modified diatomaceous earth can effectively fill the capillaries and microcracks within the material, reducing pore connectivity and promoting the deposition of more hydration products on the pore walls, thus increasing the overall density of the matrix and effectively hindering the penetration of water and corrosive media. When unmodified diatomaceous earth or no diatomaceous earth was used, the pore structure optimization effect was significantly weakened, resulting in varying degrees of decrease in impermeability.

[0044] The cumulative chloride ion flux test results for Examples 1-3 were 980°C, 720°C, and 830°C, respectively, all significantly lower than those of Comparative Example 1 (1260°C) and Comparative Example 2 (1550°C). Example 2 showed the lowest flux, indicating its strongest resistance to chloride ion penetration. This is because the synergistically modified diatomaceous earth not only improved the material's density but also optimized the pore size distribution, reduced the proportion of interconnected pores, and effectively extended the chloride ion migration path, thereby significantly reducing the chloride ion diffusion rate and improving the material's durability in corrosive environments such as salt spray, marine environments, and underground engineering.

[0045] The water absorption rates of Examples 1-3 were 4.65%, 3.58%, and 3.96%, respectively, all lower than those of Comparative Example 1 (5.42%) and Comparative Example 2 (6.05%), with Example 2 showing the lowest rate. This indicates that synergistic modification of diatomaceous earth can further improve the internal pore structure of the material, reduce the number of open and interconnected pores, and improve the interfacial bonding quality, resulting in a lower water absorption rate and superior waterproofing and seepage prevention capabilities. When the proportion of modifier is too low or too high, the pore structure optimization effect decreases. Therefore, the water absorption rates of Examples 1 and 3 are slightly higher than that of Example 2, but they still maintain good seepage prevention performance.

[0046] In summary, this invention, through the synergistic modification of diatomaceous earth by sodium aluminate-induced activation and sodium silicate mineralization, combined with a rational formulation design, achieves synergistic optimization of the internal pore structure and interface structure of the new building material. This significantly improves the material's impermeability, chloride ion resistance, and waterproofing performance while maintaining high mechanical properties. Example 2, due to the optimal synergistic effect of the component ratios, demonstrates superior overall performance compared to other examples and comparative examples, fully verifying the excellent application value and promising prospects of this invention.

Claims

1. A novel porous building material with high corrosion resistance and impermeability, characterized in that, The raw materials include the following parts by weight: 100-150 parts of ordinary silicate cement; 20-60 parts of fly ash; 15-50 parts of slag powder; 8-30 parts of synergistically modified diatomaceous earth; 20-80 parts of vitrified microspheres; 0.2-2 parts of polycarboxylate superplasticizer; 0.2-2 parts of silane water-repellent agent; and 25-60 parts of deionized water. The synergistically modified diatomaceous earth is prepared by synergistic modification of diatomaceous earth through sodium aluminate-induced activation and sodium silicate mineralization.

2. The new high corrosion-resistant and impermeable porous building material according to claim 1, characterized in that, The synergistically modified diatomaceous earth comprises the following raw materials in parts by weight: 100-150 parts diatomaceous earth; 5-20 parts sodium aluminate; 8-25 parts sodium silicate; and 150-300 parts deionized water.

3. A new type of highly corrosion-resistant and impermeable porous building material according to claim 1 or 2, characterized in that, The preparation method of the synergistically modified diatomite includes the following steps: (1) Diatomaceous earth is acid-activated to obtain activated diatomaceous earth; (2) The activated diatomaceous earth is mixed with sodium aluminate to carry out an activation reaction, thereby obtaining aluminum-activated diatomaceous earth; (3) Aluminum-activated diatomite is mixed with sodium silicate for mineralization reaction, and then subjected to solid-liquid separation, washing, drying and pulverization to obtain the synergistically modified diatomite.

4. The new high corrosion-resistant and impermeable porous building material according to claim 3, characterized in that, The reaction conditions for step (1) are as follows: a hydrochloric acid solution with a mass fraction of 5-10% is used as the acid activator, the liquid-solid ratio is 3:1-8:1, the mixture is stirred at 50-70℃ for 2-4 hours, filtered, washed with deionized water until neutral, and then dried at 80-100℃ for 6-10 hours.

5. A new high corrosion-resistant and impermeable porous building material according to claim 3, characterized in that, The reaction conditions for step (2) are as follows: the mass ratio of sodium aluminate to activated diatomaceous earth is 0.05:1 to 0.20:1, and the reaction is carried out at 60 to 80°C for 2 to 4 hours. After the reaction is completed, the mixture is filtered and washed.

6. A new high corrosion-resistant and impermeable porous building material according to claim 3, characterized in that, The reaction conditions for step (3) are as follows: the mass ratio of sodium silicate to aluminum-activated diatomite is 0.08:1 to 0.25:1, the reaction is stirred at 70 to 90°C for 3 to 5 hours, after the reaction is completed, the mixture is filtered, washed, dried at 100 to 110°C for 8 to 12 hours, and pulverized to 100 to 200 mesh.

7. A new high corrosion-resistant and impermeable porous building material according to claim 1, characterized in that, The polycarboxylate superplasticizer is prepared by mixing polycarboxylate superplasticizer mother liquor with a solid content of 35-45% with deionized water at a mass ratio of 1:(0.2-1); the silane hydrophobic agent is prepared by mixing isooctyltriethoxysilane with deionized water at a mass ratio of 1:(5-15).

8. A method for preparing a new porous building material with high corrosion resistance and impermeability, characterized in that, The preparation method includes the following steps: S1, ordinary silicate cement, fly ash, slag powder, synergistically modified diatomaceous earth and vitrified microspheres are added to the mixing equipment according to the proportion and mixed evenly to obtain mixed powder; S2, mix polycarboxylate superplasticizer, silane water-repellent agent and deionized water evenly to obtain a mixture; add the mixture to the mixed powder and continue stirring to obtain a uniform slurry; S3. The slurry is injected into the mold to form a new type of porous building material with high corrosion resistance and impermeability after standing, demolding and curing.

9. The method for preparing a new type of highly corrosion-resistant and impermeable porous building material according to claim 8, characterized in that, The reaction conditions for step S1 are as follows: mixing is carried out using a horizontal forced mixer at a speed of 60-120 r / min for 5-10 min; the reaction conditions for step S2 are as follows: the mixture is added to the mixed powder at once, stirred at 150-300 r / min for 3-5 min, and then stirred at 300-600 r / min for 2-5 min to obtain a uniform slurry.

10. The method for preparing a new type of highly corrosion-resistant and impermeable porous building material according to claim 8, characterized in that, The reaction conditions for step S3 are as follows: after the slurry is injected into the mold, it is vibrated for 30-90 seconds, allowed to stand for 12-24 hours, and then demolded. The slurry is then cured under standard conditions of 20±2℃ and relative humidity not less than 95% for 28 days to obtain the new high corrosion-resistant and impermeable porous building material.

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